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Marick S, Takasu F, Bairagi N. How do productivity gradient and diffusion shape patterns in a plant-herbivore grazing system? J Theor Biol 2024; 590:111856. [PMID: 38777134 DOI: 10.1016/j.jtbi.2024.111856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/05/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024]
Abstract
Natural systems show heterogeneous patchy distributions of vegetation over large landscapes. Reaction-diffusion systems can demonstrate such heterogeneity of species distributions. Here, we analyse a reaction-diffusion model of plant-herbivore interactions in two-dimensional space to illustrate non-homogeneous distributions of plants and herbivores. The non-spatial system shows bottom-up control, where herbivore density is low under low and high primary productivity but increased at intermediate productivity. In addition, the non-spatial system provides bistability between a dense vegetation state devoid of herbivores and a coexisting state of plants and herbivores. In the spatiotemporal model, we give analytical conditions of occurring diffusion-driven (Turing) instability, where a novel point in our model is the relative dispersal of herbivores, which represents the movement of herbivores from a higher to a lower vegetation state in addition to the self-diffusion of both species. It is shown that heterogeneity in the population distribution does not occur if the relative dispersal of herbivores is low, but it appears in the opposite case. Due to bistability in the underlying non-spatial system, the spatiotemporal model produces initial value-dependent patterns. The two initial values make different patterns despite having the same primary productivity and relative dispersal rate. As productivity increases with a given relative herbivore dispersal, pattern transition occurs from a blend of stripes and spots of low vegetation state to a predominantly low-density vegetation state with smaller patches of densely vegetated states with one initial value. On the contrary, a discernible change in vegetation patterns from cold spots in the dense vegetation to hot stripes in the primarily low-vegetated state is noticed under the other initial population value. Furthermore, the population distributions of plants and herbivores in the entire domain after a long period are heterogeneous for both initial values, provided the relative herbivore dispersal is substantial. We estimated mean population densities to observe species fitness in the whole domain under variable productivity. When productivity is high, the mean population density of plants may go up or down, depending on the herbivore's relative dispersal rate. In contrast to the bottom-up control dynamics of the non-spatial system, the system exhibits a top-down control under high relative dispersal, where the herbivore regulates vegetation growth under high productivity. On the other hand, herbivores are extinct under high productivity if the relative dispersal is low.
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Affiliation(s)
- Sounov Marick
- Centre for Mathematical Biology and Ecology, Department of Mathematics, Jadavpur University, Kolkata 700032, India
| | - Fugo Takasu
- Department of Environmental Science, Nara Women's University, Nara, Japan
| | - Nandadulal Bairagi
- Centre for Mathematical Biology and Ecology, Department of Mathematics, Jadavpur University, Kolkata 700032, India.
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2
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Xie Y, Hua Y, Zhang J, Wei W, Yin B. Brandt's vole ( Lasiopodomys brandtii) affects the dominant position of three gramineous species by altering defense traits and interspecific competition. Ecol Evol 2024; 14:e70086. [PMID: 39091336 PMCID: PMC11293948 DOI: 10.1002/ece3.70086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2024] [Revised: 05/10/2024] [Accepted: 07/17/2024] [Indexed: 08/04/2024] Open
Abstract
Rodents can cause considerable changes in plant community composition. However, relationships between shifts in species dominance and plant functional traits caused by rodents have seldom been investigated, especially for belowground functional traits. In this study, a set of enclosures was constructed to analyze the effects of 10 years of Brandt's voles' activities on the defense strategies and dominant position changes of three gramineous plants (Leymus chinensis, Stipa krylovii, and Cleistogenes squarrosa) in Inner Mongolia. Here, we measured the dominance, biomass, and fourteen functional traits of three plants. The effects of Brandt's voles on dominance, biomass, and functional traits were analyzed, and then we explored the effect of functional traits on plant dominance by using the structural equation model. Results showed that long-term feeding by Brandt's voles resulted in a significant decrease in the dominance of L. chinensis and S. krylovii, whereas C. squarrosa was positively affected. The belowground biomass of L. chinensis and S. krylovii was higher in the vole treatment, which showed that they were increasing their escape characteristics. The leaf thickness of L. chinensis and the leaf C:N ratio of S. krylovii significantly increased, while the specific leaf area of C. squarrosa significantly decreased. All three gramineous showed increased resistance traits in response to Brandt's voles, which positively affected their dominance. Tolerance-related traits of S. krylovii significantly increased, with the increasing growth rate of root length contributing to enhancing its dominance. We highlight that selective feeding by rodents led to the selection of different defense strategies by three gramineous plants, and that changes in biomass allocation and functional traits in the different species affected plant dominance, driving changes in the plant communities.
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Affiliation(s)
- Yanjin Xie
- College of Bioscience and BiotechnologyYangzhou UniversityYangzhouChina
| | - Yongle Hua
- College of Bioscience and BiotechnologyYangzhou UniversityYangzhouChina
| | - Jiading Zhang
- College of Bioscience and BiotechnologyYangzhou UniversityYangzhouChina
| | - Wanhong Wei
- College of Bioscience and BiotechnologyYangzhou UniversityYangzhouChina
| | - Baofa Yin
- College of Bioscience and BiotechnologyYangzhou UniversityYangzhouChina
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3
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Karp AT, Koerner SE, Hempson GP, Abraham JO, Anderson TM, Bond WJ, Burkepile DE, Fillion EN, Goheen JR, Guyton JA, Kartzinel TR, Kimuyu DM, Mohanbabu N, Palmer TM, Porensky LM, Pringle RM, Ritchie ME, Smith MD, Thompson DI, Young TP, Staver AC. Grazing herbivores reduce herbaceous biomass and fire activity across African savannas. Ecol Lett 2024; 27:e14450. [PMID: 38857323 DOI: 10.1111/ele.14450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 06/12/2024]
Abstract
Fire and herbivory interact to alter ecosystems and carbon cycling. In savannas, herbivores can reduce fire activity by removing grass biomass, but the size of these effects and what regulates them remain uncertain. To examine grazing effects on fuels and fire regimes across African savannas, we combined data from herbivore exclosure experiments with remotely sensed data on fire activity and herbivore density. We show that, broadly across African savannas, grazing herbivores substantially reduce both herbaceous biomass and fire activity. The size of these effects was strongly associated with grazing herbivore densities, and surprisingly, was mostly consistent across different environments. A one-zebra increase in herbivore biomass density (~100 kg/km2 of metabolic biomass) resulted in a ~53 kg/ha reduction in standing herbaceous biomass and a ~0.43 percentage point reduction in burned area. Our results indicate that fire models can be improved by incorporating grazing effects on grass biomass.
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Affiliation(s)
- Allison Tyler Karp
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
- Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, Rhode Island, USA
| | - Sally E Koerner
- Department of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, USA
| | - Gareth P Hempson
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Joel O Abraham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - William J Bond
- Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Deron E Burkepile
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, USA
- South African Environmental Observation Network, Ndlovu Node, Scientific Services, Kruger National Park, Phalaborwa, South Africa
| | - Elizabeth N Fillion
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
| | - Jacob R Goheen
- Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, USA
- Mpala Research Centre, Nanyuki, Kenya
| | - Jennifer A Guyton
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Tyler R Kartzinel
- Institute at Brown for Environment and Society, Brown University, Providence, Rhode Island, USA
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - Duncan M Kimuyu
- Mpala Research Centre, Nanyuki, Kenya
- Department of Natural Resources, Karatina University, Karatina, Kenya
| | - Neha Mohanbabu
- Department of Biology, Syracuse University, Syracuse, New York, USA
- University of Minnesota, Twin Cities, Minnesota, USA
| | - Todd M Palmer
- Biological Sciences, University of Cape Town, Cape Town, South Africa
- Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Lauren M Porensky
- Rangeland Resources and Systems Research Unit, USDA Agricultural Research Service, Fort Collins, Colorado, USA
| | - Robert M Pringle
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Mark E Ritchie
- Department of Wildland Resources, Utah State University, Logan, Utah, USA
| | - Melinda D Smith
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Dave I Thompson
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
- South African Environmental Observation Network, Ndlovu Node, Scientific Services, Kruger National Park, Phalaborwa, South Africa
| | - Truman P Young
- Mpala Research Centre, Nanyuki, Kenya
- Department of Plant Sciences, University of California Davis, Davis, California, USA
| | - A Carla Staver
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, USA
- Yale Institute for Biospheric Studies, Yale University, New Haven, Connecticut, USA
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4
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Mata JC, Davison CW, Frøslev TG, Buitenwerf R, Svenning JC. Resource partitioning in a novel herbivore assemblage in South America. J Anim Ecol 2024; 93:606-618. [PMID: 38414265 DOI: 10.1111/1365-2656.14069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 02/06/2024] [Indexed: 02/29/2024]
Abstract
Human-induced species declines and extinctions have led to the downsizing of large-herbivore assemblages, with implications for many ecosystem processes. Active reintroduction of extirpated large herbivores or their functional equivalents may help to reverse this trend and restore diverse ecosystems and their processes. However, it is unclear whether resource competition between native and non-native herbivores could threaten restoration initiatives, or to what extent (re)introduced species may influence local vegetation dynamics. To answer these questions, we investigated the diets of a novel South American herbivore assemblage that includes resident native species, reintroduced native species and introduced non-native species. We examined plant composition, diet breadth and the overlap between species to describe the local herbivory profile and the potential for resource competition. Using DNA metabarcoding on faecal samples (n = 465), we analysed the diets of the herbivore assemblage in the Rincón del Socorro rewilding area of Iberá National Park, Argentina. We compared the species richness of faecal samples, the occurrence of plant families/growth forms and the compositional similarity of samples (inter- and intraspecifically). Our results indicate species-level taxonomic partitioning of plant resources by herbivores in this system. Differences in sample richness, composition and diet breadth reflected a diverse range of herbivory strategies, from grazers (capybara) to mixed feeders/browsers (brocket deer, lowland tapir). Differences in diet compositional similarity (Jaccard) revealed strong taxonomic resource partitioning. The two herbivores with the most similar diets (Pampas deer and brocket deer) still differed by more than 80%. Furthermore, all but one species (axis deer) had more similar diet composition intraspecifically than compared to the others. Overall, we found little evidence for resource competition between herbivore species. Instead, recently reintroduced native species and historically introduced non-natives are likely expanding the range of herbivory dynamics in the ecosystem. Further research will be needed to determine the full ecological impacts of these (re)introduced herbivores. In conclusion, we show clear differences in diet breadth and composition among native, reintroduced and non-native herbivore species that may be key to promoting resource partitioning, species coexistence and the restoration of ecological function.
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Affiliation(s)
- Julia C Mata
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Charles W Davison
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
| | | | - Robert Buitenwerf
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Jens-Christian Svenning
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
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Trepel J, le Roux E, Abraham AJ, Buitenwerf R, Kamp J, Kristensen JA, Tietje M, Lundgren EJ, Svenning JC. Meta-analysis shows that wild large herbivores shape ecosystem properties and promote spatial heterogeneity. Nat Ecol Evol 2024; 8:705-716. [PMID: 38337048 DOI: 10.1038/s41559-024-02327-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 01/08/2024] [Indexed: 02/12/2024]
Abstract
Megafauna (animals ≥45 kg) have probably shaped the Earth's terrestrial ecosystems for millions of years with pronounced impacts on biogeochemistry, vegetation, ecological communities and evolutionary processes. However, a quantitative global synthesis on the generality of megafauna effects on ecosystems is lacking. Here we conducted a meta-analysis of 297 studies and 5,990 individual observations across six continents to determine how wild herbivorous megafauna influence ecosystem structure, ecological processes and spatial heterogeneity, and whether these impacts depend on body size and environmental factors. Despite large variability in megafauna effects, we show that megafauna significantly alter soil nutrient availability, promote open vegetation structure and reduce the abundance of smaller animals. Other responses (14 out of 26), including, for example, soil carbon, were not significantly affected. Further, megafauna significantly increase ecosystem heterogeneity by affecting spatial heterogeneity in vegetation structure and the abundance and diversity of smaller animals. Given that spatial heterogeneity is considered an important driver of biodiversity across taxonomic groups and scales, these results support the hypothesis that megafauna may promote biodiversity at large scales. Megafauna declined precipitously in diversity and abundance since the late Pleistocene, and our results indicate that their restoration would substantially influence Earth's terrestrial ecosystems.
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Affiliation(s)
- Jonas Trepel
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark.
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark.
- Department of Conservation Biology, University of Göttingen, Göttingen, Germany.
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark.
| | - Elizabeth le Roux
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Andrew J Abraham
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Robert Buitenwerf
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Johannes Kamp
- Department of Conservation Biology, University of Göttingen, Göttingen, Germany
| | - Jeppe A Kristensen
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK
| | - Melanie Tietje
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
| | - Erick J Lundgren
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark.
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark.
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark.
- School of Biology and Environmental Science, Faculty of Science, Queensland University of Technology, Brisbane, Queensland, Australia.
| | - Jens-Christian Svenning
- Center for Ecological Dynamics in a Novel Biosphere (ECONOVO), Department of Biology, Aarhus University, Aarhus C, Denmark
- Section for Ecoinformatics and Biodiversity, Department of Biology, Aarhus University, Aarhus C, Denmark
- Center for Biodiversity Dynamics in a Changing World (BIOCHANGE), Department of Biology, Aarhus University, Aarhus C, Denmark
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6
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Liu C, Gauthier G, Gignac C, Lévesque E, Rochefort L. Scale-dependent effects of herbivory on moss communities in Arctic wetlands: A 25-year experiment. Ecol Evol 2024; 14:e11272. [PMID: 38665892 PMCID: PMC11043830 DOI: 10.1002/ece3.11272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 03/17/2024] [Accepted: 04/01/2024] [Indexed: 04/28/2024] Open
Abstract
Arctic ecosystems are undergoing rapid changes, including increasing disturbance by herbivore populations, which can affect plant species coexistence and community assemblages. Although the significance of mosses in Arctic wetlands is well recognized, the long-term influence of medium-sized herbivores on the composition of moss communities has received limited attention. We used data from a long-term (25 years) Greater Snow Goose (Anser caerulescens atlanticus) exclusion experiment in Arctic tundra wetlands to assess changes in the composition of moss communities at multiple spatial scales (cell, 4 cm2; quadrat, 100 cm2; exclosure, 16 m2). We investigated how snow goose grazing and grubbing can alter the composition of the moss community by measuring changes in alpha and beta diversity, as well as in the strength of plant interspecific interactions between moss species. Our results indicate that goose foraging significantly increased species diversity (richness, evenness, and inverse Simpson index) of moss communities at the cell and quadrat scales but not the exclosure scale. Goose foraging reduced the dissimilarity (beta diversity) of moss communities at all three scales, mainly due to decreased species turnover. Furthermore, goose foraging increased positive interaction between moss species pairs. These findings emphasize the critical role of geese in promoting moss species coexistence and increasing homogeneity in Arctic wetlands. This study illustrates how top-down regulation by herbivores can alter plant communities in Arctic wetlands and highlights the importance of considering herbivores when examining the response of Arctic plant biodiversity to future climate change.
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Affiliation(s)
- Chao Liu
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
| | - Gilles Gauthier
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de BiologieUniversité LavalQuébecQuébecCanada
| | - Charles Gignac
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
| | - Esther Lévesque
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Laboratoire d'Écologie Végétale Fonctionnelle (LEAF), Département des Sciences de l'EnvironnementUniversité du Québec à Trois‐RivièresTrois‐RivièresQuébecCanada
| | - Line Rochefort
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
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7
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Tuo B, García-Palacios P, Guo C, Yan ER, Berg MP, Cornelissen JHC. Meta-analysis reveals that vertebrates enhance plant litter decomposition at the global scale. Nat Ecol Evol 2024; 8:411-422. [PMID: 38195996 DOI: 10.1038/s41559-023-02292-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 11/27/2023] [Indexed: 01/11/2024]
Abstract
Evidence is mounting that vertebrate defaunation greatly impacts global biogeochemical cycling. Yet, there is no comprehensive assessment of the potential vertebrate influence over plant decomposition, despite litter decay being one of the largest global carbon fluxes. We therefore conducted a global meta-analysis to evaluate vertebrate effects on litter mass loss and associated element release across terrestrial and aquatic ecosystems. Here we show that vertebrates affected litter decomposition by various direct and indirect pathways, increasing litter mass loss by 6.7% on average, and up to 34.4% via physical breakdown. This positive vertebrate impact on litter mass loss was consistent across contrasting litter types (woody and non-woody), climatic regions (boreal, temperate and tropical), ecosystem types (aquatic and terrestrial) and vertebrate taxa, but disappeared when evaluating litter nitrogen and phosphorus release. Moreover, we found evidence of interactive effects between vertebrates and non-vertebrate decomposers on litter mass loss, and a larger influence of vertebrates at mid-to-late decomposition stages, contrasting with the invertebrate effect known to be strongest at early decomposition stage. Our synthesis demonstrates a global vertebrate control over litter mass loss, and further stresses the need to account for vertebrates when assessing the impacts of biodiversity loss on biogeochemical cycles.
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Affiliation(s)
- Bin Tuo
- A-LIFE, Systems Ecology, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Pablo García-Palacios
- Instituto de Ciencias Agrarias (ICA), CSIC, Madrid, Spain
- Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland
| | - Chao Guo
- Forest Zoology, Technische Universität Dresden, Tharandt, Germany.
| | - En-Rong Yan
- Zhejiang Zhoushan Archipelago Observation and Research Station, Tiantong National Forest Ecosystem Observation and Research Station, and Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
- Institute of Eco-Chongming (IEC), Shanghai, China
| | - Matty P Berg
- A-LIFE, Ecology & Evolution, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
- GELIFES, Conservation and Community Ecology Group, University of Groningen, Groningen, The Netherlands
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8
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Harris NC, Bhandari A, Doamba B. Ungulate co-occurrence in a landscape of antagonisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169552. [PMID: 38142990 DOI: 10.1016/j.scitotenv.2023.169552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 12/26/2023]
Abstract
Protected areas largely now exist as coupled natural-human ecosystems where human activities are increasingly forcing wildlife to adjust behaviors. For many ungulate species that rely on protected areas for their persistence, they must balance these anthropogenic pressures amid natural regulators. Here, we investigated the pressures exerted from humans and livestock, apex predators, and within guild competitors on ungulate co-occurrence patterns in a fragile protected area complex in West Africa. Specifically, we used multi-species occupancy modeling to quantify co-occurrence among four ungulates (Tragelaphus scriptus, Redunca redunca, Kobus kob, Phacochoerus africanus) and applied structural equation models to discern the relative contributions of pressures on co-occurrence patterns. We observed a strong spatial gradient across with higher co-occurrence in the wetter western portion of our ~13,000 km2 study area. Co-occurrence patterns among ungulate dyads ranged from 0.15 to 0.49 with the smallest body sized pair showing highest levels of sympatry, warthog and reedbuck. We found that anthropogenic pressures, namely cattle had the greatest effect in reducing sympatry among wild ungulates more strongly than the presence of African lions that also exhibited negative effects. Humans, hyenas, and competitors showed positive effects on ungulate co-occurrence. In a region of the world ongoing rapid socio-ecological change with increasing threats from climate and environmental instability, protected areas in West Africa represent a major safeguard for wildlife and human livelihoods alike. Our findings highlight the need for effective interventions that focus on large carnivore conservation, habitat restoration, and containment of livestock grazing to promote the coexistence of biodiversity and socio-economic goals within the region.
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Affiliation(s)
- Nyeema C Harris
- Applied Wildlife Ecology (AWE) Lab, Yale School of the Environment, United States of America.
| | - Aishwarya Bhandari
- Applied Wildlife Ecology (AWE) Lab, Yale School of the Environment, United States of America
| | - Benoit Doamba
- National Office of Protected Areas (OFINAP), Ouagadougou, Burkina Faso
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9
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Wood TJ, Müller A, Praz C, Michez D. Elevated rates of dietary generalization in eusocial lineages of the secondarily herbivorous bees. BMC Ecol Evol 2023; 23:67. [PMID: 37986035 PMCID: PMC10662511 DOI: 10.1186/s12862-023-02175-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/16/2023] [Indexed: 11/22/2023] Open
Abstract
BACKGROUND Within the Hymenoptera, bees are notable for their relationship with flowering plants, being almost entirely dependent on plant pollen and nectar. Though functionally herbivorous, as a result of their role as pollinators, bees have received comparatively little attention as models for insect herbivory. Bees often display dietary specialization, but quantitative comparison against other herbivorous insects has not previously been conducted. RESULTS In the most comprehensive analysis to date for 860 bee species, dietary specialization amounted to 50.1% of studied species collecting pollen from between 1 and 2 botanical families with a relatively long tail of dietary generalists, with 11.1% of species collecting from more than 10 botanical families. This distribution deviated from the truncated Pareto distribution of dietary breadth seen in other herbivorous insect lineages. However, this deviation was predominantly due to eusocial bee lineages, which show a range of dietary breadths that conformed to a normal distribution, while solitary bees show a typical truncated distribution not strongly different from other herbivorous insects. We hypothesize that the relatively low level of dietary specialization in bees as a whole reflects the relaxation of the constraints typically observed in herbivorous insects with a comparatively reduced importance of plant chemistry and comparatively increased importance of phenology and foraging efficiency. The long flight periods of eusocial bees that are necessary to allow overlapping generations both allows and necessitates the use of multiple flowering resources, whereas solitary bees with short flight periods have more limited access to varied resources within a constrained activity period. CONCLUSIONS Collectively, solitary bees show slightly lower specialization compared to other herbivorous insects, possibly due to their balanced relationship with plants, rather than direct antagonism such as seen in the direct consumption of plant tissues. An additional factor may be the mediocre diversity of bees at low latitudes combined with low levels of dietary specialization, whereas these areas typically display a high rate of specialization by herbivorous insects in general. Though the most important factors structuring dietary specialization in bees appear to differ from many other herbivorous insects, solitary bees show a surprisingly similar overall pattern of dietary specialization.
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Affiliation(s)
- T J Wood
- University of Mons, Research Institute for Biosciences, Laboratory of Zoology, Place du parc 20, 7000, Mons, Belgium.
| | - A Müller
- ETH Zurich, Institute of Agricultural Sciences, Biocommunication and Entomology, Schmelzbergstrasse 9/LFO, 8092, Zurich, Switzerland
| | - C Praz
- University of Neuchâtel, Institute of Biology, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
- InfoFauna - Swiss Zoological Records Center, Avenue de Bellevaux 51, 2000, Neuchâtel, Switzerland
| | - D Michez
- University of Mons, Research Institute for Biosciences, Laboratory of Zoology, Place du parc 20, 7000, Mons, Belgium
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10
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Xu C, Silliman BR, Chen J, Li X, Thomsen MS, Zhang Q, Lee J, Lefcheck JS, Daleo P, Hughes BB, Jones HP, Wang R, Wang S, Smith CS, Xi X, Altieri AH, van de Koppel J, Palmer TM, Liu L, Wu J, Li B, He Q. Herbivory limits success of vegetation restoration globally. Science 2023; 382:589-594. [PMID: 37917679 DOI: 10.1126/science.add2814] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/21/2023] [Indexed: 11/04/2023]
Abstract
Restoring vegetation in degraded ecosystems is an increasingly common practice for promoting biodiversity and ecological function, but successful implementation is hampered by an incomplete understanding of the processes that limit restoration success. By synthesizing terrestrial and aquatic studies globally (2594 experimental tests from 610 articles), we reveal substantial herbivore control of vegetation under restoration. Herbivores at restoration sites reduced vegetation abundance more strongly (by 89%, on average) than those at relatively undegraded sites and suppressed, rather than fostered, plant diversity. These effects were particularly pronounced in regions with higher temperatures and lower precipitation. Excluding targeted herbivores temporarily or introducing their predators improved restoration by magnitudes similar to or greater than those achieved by managing plant competition or facilitation. Thus, managing herbivory is a promising strategy for enhancing vegetation restoration efforts.
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Affiliation(s)
- Changlin Xu
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Brian R Silliman
- Nicholas School of the Environment, Duke University, Beaufort, NC, USA
| | - Jianshe Chen
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Xincheng Li
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Mads S Thomsen
- Marine Ecology Research Group and Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Bioscience, Aarhus University, Roskilde, Denmark
| | - Qun Zhang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
| | - Juhyung Lee
- Marine Science Center, Northeastern University, Nahant, MA, USA
- Department of Oceanography and Marine Research Institute, Pusan National University, Busan, Republic of Korea
| | - Jonathan S Lefcheck
- Tennenbaum Marine Observatories Network and MarineGEO Program, Smithsonian Environmental Research Center, Edgewater, MD, USA
- University of Maryland Center for Environmental Science, Cambridge, MD, USA
| | - Pedro Daleo
- Instituto de Investigaciones Marinas y Costeras (IIMyC), UNMdP, CONICETC, Mar del Plata, Argentina
| | - Brent B Hughes
- Department of Biology, Sonoma State University, Rohnert Park, CA, USA
| | - Holly P Jones
- Department of Biological Sciences and Institute for the Study of the Environment, Sustainability, and Energy, Northern Illinois University, DeKalb, IL, USA
| | - Rong Wang
- School of Ecological and Environmental Sciences, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, East China Normal University, Shanghai, China
| | - Shaopeng Wang
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Carter S Smith
- Nicholas School of the Environment, Duke University, Beaufort, NC, USA
| | - Xinqiang Xi
- Department of Ecology, School of Life Science, Nanjing University, Nanjing, Jiangsu, China
| | - Andrew H Altieri
- Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, USA
| | - Johan van de Koppel
- Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Yerseke, Netherlands
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Todd M Palmer
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Jihua Wu
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, and College of Ecology, Lanzhou University, Lanzhou, Gansu, China
| | - Bo Li
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, Yunnan, China
| | - Qiang He
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, School of Life Sciences, Fudan University, Shanghai, China
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11
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Wang X, He Y, Sedio BE, Jin L, Ge X, Glomglieng S, Cao M, Yang J, Swenson NG, Yang J. Phytochemical diversity impacts herbivory in a tropical rainforest tree community. Ecol Lett 2023; 26:1898-1910. [PMID: 37776563 DOI: 10.1111/ele.14308] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/24/2023] [Accepted: 08/25/2023] [Indexed: 10/02/2023]
Abstract
Metabolomics provides an unprecedented window into diverse plant secondary metabolites that represent a potentially critical niche dimension in tropical forests underlying species coexistence. Here, we used untargeted metabolomics to evaluate chemical composition of 358 tree species and its relationship with phylogeny and variation in light environment, soil nutrients, and insect herbivore leaf damage in a tropical rainforest plot. We report no phylogenetic signal in most compound classes, indicating rapid diversification in tree metabolomes. We found that locally co-occurring species were more chemically dissimilar than random and that local chemical dispersion and metabolite diversity were associated with lower herbivory, especially that of specialist insect herbivores. Our results highlight the role of secondary metabolites in mediating plant-herbivore interactions and their potential to facilitate niche differentiation in a manner that contributes to species coexistence. Furthermore, our findings suggest that specialist herbivore pressure is an important mechanism promoting phytochemical diversity in tropical forests.
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Affiliation(s)
- Xuezhao Wang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
- School of Ecology and Environment, Southwest Forestry University, Kunming, China
| | - Yunyun He
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Brian E Sedio
- Department of Integrative Biology, University of Texas at Austin, Texas, Austin, USA
- Smithsonian Tropical Research Institute, Ancón, Republic of Panama
| | - Lu Jin
- College of Life Sciences, South China Agricultural University, Guangzhou, China
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Xuejun Ge
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Suphanee Glomglieng
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Min Cao
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China
| | - Jianhong Yang
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Nathan G Swenson
- Department of Biological Sciences, University of Notre Dame, Indiana, Notre Dame, USA
| | - Jie Yang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, China
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12
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Moore JH, Gibson L, Amir Z, Chanthorn W, Ahmad AH, Jansen PA, Mendes CP, Onuma M, Peres CA, Luskin MS. The rise of hyperabundant native generalists threatens both humans and nature. Biol Rev Camb Philos Soc 2023; 98:1829-1844. [PMID: 37311559 DOI: 10.1111/brv.12985] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 06/15/2023]
Abstract
In many disturbed terrestrial landscapes, a subset of native generalist vertebrates thrives. The population trends of these disturbance-tolerant species may be driven by multiple factors, including habitat preferences, foraging opportunities (including crop raiding or human refuse), lower mortality when their predators are persecuted (the 'human shield' effect) and reduced competition due to declines of disturbance-sensitive species. A pronounced elevation in the abundance of disturbance-tolerant wildlife can drive numerous cascading impacts on food webs, biodiversity, vegetation structure and people in coupled human-natural systems. There is also concern for increased risk of zoonotic disease transfer to humans and domestic animals from wildlife species with high pathogen loads as their abundance and proximity to humans increases. Here we use field data from 58 landscapes to document a supra-regional phenomenon of the hyperabundance and community dominance of Southeast Asian wild pigs and macaques. These two groups were chosen as prime candidates capable of reaching hyperabundance as they are edge adapted, with gregarious social structure, omnivorous diets, rapid reproduction and high tolerance to human proximity. Compared to intact interior forests, population densities in degraded forests were 148% and 87% higher for wild boar and macaques, respectively. In landscapes with >60% oil palm coverage, wild boar and pig-tailed macaque estimated abundances were 337% and 447% higher than landscapes with <1% oil palm coverage, respectively, suggesting marked demographic benefits accrued by crop raiding on calorie-rich food subsidies. There was extreme community dominance in forest landscapes with >20% oil palm cover where two pig and two macaque species accounted for >80% of independent camera trap detections, leaving <20% for the other 85 mammal species >1 kg considered. Establishing the population trends of pigs and macaques is imperative since they are linked to cascading impacts on the fauna and flora of local forest ecosystems, disease and human health, and economics (i.e., crop losses). The severity of potential negative cascading effects may motivate control efforts to achieve ecosystem integrity, human health and conservation objectives. Our review concludes that the rise of native generalists can be mediated by specific types of degradation, which influences the ecology and conservation of natural areas, creating both positive and detrimental impacts on intact ecosystems and human society.
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Affiliation(s)
- Jonathan H Moore
- School of Environmental Science and Engineering, Southern University of Science and Technology, 1088 Xueyuan Blvd, Nanshan, Shenzhen, China
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Luke Gibson
- School of Environmental Science and Engineering, Southern University of Science and Technology, 1088 Xueyuan Blvd, Nanshan, Shenzhen, China
| | - Zachary Amir
- School of Biological Sciences, University of Queensland, Brisbane, St Lucia, Queensland, 4072, Australia
| | - Wirong Chanthorn
- Department of Environmental Technology and Management, Faculty of Environment, Kasetsart University, 50 Ngamwongwan Road, Jatujak District, Bangkok, 10900, Thailand
| | - Abdul Hamid Ahmad
- Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Jalan UMS, Kota Kinabalu, 88400, Malaysia
| | - Patrick A Jansen
- Department of Environmental Sciences, Wageningen University, Droevendaalsesteeg 4, Wageningen, 6708 PB, Netherlands
- Smithsonian Tropical Research Institute, Roosevelt Ave. Tupper Building - 401, Panama City, 0843-03092, Panama
| | - Calebe P Mendes
- School of Biological Sciences, University of Queensland, Brisbane, St Lucia, Queensland, 4072, Australia
| | - Manabu Onuma
- National Institute for Environmental Studies, 16-2 Onagava, Tsukuba-City, 305-8506, Japan
| | - Carlos A Peres
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
- Instituto Juruá, R. Ajuricaba, 359 - Aleixo, Manaus, 69083-020, Brazil
| | - Matthew Scott Luskin
- School of Biological Sciences, University of Queensland, Brisbane, St Lucia, Queensland, 4072, Australia
- Centre for Biodiversity and Conservation Science, University of Queensland, St Lucia, Queensland, 4072, Australia
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13
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Wang N, Shibata Y, Paulo JA, Gygi SP, Rapoport TA. A conserved membrane curvature-generating protein is crucial for autophagosome formation in fission yeast. Nat Commun 2023; 14:4765. [PMID: 37553386 PMCID: PMC10409813 DOI: 10.1038/s41467-023-40530-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 07/26/2023] [Indexed: 08/10/2023] Open
Abstract
Organelles are shaped by curvature-generating proteins, which include the reticulons and REEPs that are involved in forming the endoplasmic reticulum (ER). A conserved REEP subfamily differs from the ER-shaping REEPs in abundance and membrane topology and has unidentified functions. Here, we show that Rop1, the single member of this family in the fission yeast Schizosacharomyces pombe, is crucial for the macroautophagy of organelles and cytosolic proteins. Rop1 is needed for the formation of phagophores, cup-like structures consisting of two closely apposed membrane sheets that encapsulate cargo. It is recruited at early stages to phagophores and is required for their maturation into autophagosomes. Rop1 function relies on its ability to generate high membrane curvature and on its colocalization with the autophagy component Atg2 that is thought to reside at the phagophore rim. We propose that Rop1 facilitates the formation and growth of the double-membrane structure of the autophagosome.
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Affiliation(s)
- Ning Wang
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Yoko Shibata
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
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14
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Higgins SI, Conradi T, Kruger LM, O'Hara RB, Slingsby JA. Limited climatic space for alternative ecosystem states in Africa. Science 2023; 380:1038-1042. [PMID: 37289873 DOI: 10.1126/science.add5190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 05/12/2023] [Indexed: 06/10/2023]
Abstract
One of the foundational premises of ecology is that climate determines ecosystems. This has been challenged by alternative ecosystem state models, which illustrate that internal ecosystem dynamics acting on the initial ecosystem state can overwhelm the influence of climate, and by observations suggesting that climate cannot reliably discriminate forest and savanna ecosystem types. Using a novel phytoclimatic transform, which estimates the ability of climate to support different types of plants, we show that climatic suitability for evergreen trees and C4 grasses are sufficient to discriminate between forest and savanna in Africa. Our findings reassert the dominant influence of climate on ecosystems and suggest that the role of feedbacks causing alternative ecosystem states is less prevalent than has been suggested.
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Affiliation(s)
- Steven I Higgins
- Plant Ecology, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Timo Conradi
- Plant Ecology, University of Bayreuth, Universitaetsstrasse 30, 95447 Bayreuth, Germany
| | - Laurence M Kruger
- Organization for Tropical Studies, P.O. Box 33, Skukuza, 1350, South Africa
- Department of Biological Sciences, University of Cape Town, South Africa
| | - Robert B O'Hara
- Department of Mathematical Sciences, Norwegian University of Science and Technology, Trondheim N-7491 Norway
| | - Jasper A Slingsby
- Department of Biological Sciences, University of Cape Town, South Africa
- Centre for Statistics in Ecology, the Environment and Conservation, University of Cape Town, South Africa
- Fynbos Node, South African Environmental Observation Network (SAEON), South Africa
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15
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Pringle RM, Abraham JO, Anderson TM, Coverdale TC, Davies AB, Dutton CL, Gaylard A, Goheen JR, Holdo RM, Hutchinson MC, Kimuyu DM, Long RA, Subalusky AL, Veldhuis MP. Impacts of large herbivores on terrestrial ecosystems. Curr Biol 2023; 33:R584-R610. [PMID: 37279691 DOI: 10.1016/j.cub.2023.04.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Large herbivores play unique ecological roles and are disproportionately imperiled by human activity. As many wild populations dwindle towards extinction, and as interest grows in restoring lost biodiversity, research on large herbivores and their ecological impacts has intensified. Yet, results are often conflicting or contingent on local conditions, and new findings have challenged conventional wisdom, making it hard to discern general principles. Here, we review what is known about the ecosystem impacts of large herbivores globally, identify key uncertainties, and suggest priorities to guide research. Many findings are generalizable across ecosystems: large herbivores consistently exert top-down control of plant demography, species composition, and biomass, thereby suppressing fires and the abundance of smaller animals. Other general patterns do not have clearly defined impacts: large herbivores respond to predation risk but the strength of trophic cascades is variable; large herbivores move vast quantities of seeds and nutrients but with poorly understood effects on vegetation and biogeochemistry. Questions of the greatest relevance for conservation and management are among the least certain, including effects on carbon storage and other ecosystem functions and the ability to predict outcomes of extinctions and reintroductions. A unifying theme is the role of body size in regulating ecological impact. Small herbivores cannot fully substitute for large ones, and large-herbivore species are not functionally redundant - losing any, especially the largest, will alter net impact, helping to explain why livestock are poor surrogates for wild species. We advocate leveraging a broad spectrum of techniques to mechanistically explain how large-herbivore traits and environmental context interactively govern the ecological impacts of these animals.
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Affiliation(s)
- Robert M Pringle
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Joel O Abraham
- Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston Salem, NC 27109, USA
| | - Tyler C Coverdale
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Andrew B Davies
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | | | | | - Jacob R Goheen
- Department of Zoology & Physiology, University of Wyoming, Laramie, WY 82072, USA
| | - Ricardo M Holdo
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA
| | - Matthew C Hutchinson
- Department of Life & Environmental Sciences, University of California Merced, Merced, CA 95343, USA
| | - Duncan M Kimuyu
- Department of Natural Resources, Karatina University, Karatina, Kenya
| | - Ryan A Long
- Department of Fish and Wildlife Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Amanda L Subalusky
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Michiel P Veldhuis
- Institute of Environmental Sciences, Leiden University, 2333 CC Leiden, The Netherlands
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16
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Bona K, Delabie JH, Cazetta E. Effects of anthropogenic disturbances on diaspore removal by ants: A meta-analysis. ACTA OECOLOGICA 2023. [DOI: 10.1016/j.actao.2023.103893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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17
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Williams PJ, Brodie JF. Predicting how defaunation-induced changes in seed predation and dispersal will affect tropical tree populations. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2023; 37:e14014. [PMID: 36178021 DOI: 10.1111/cobi.14014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
The loss of large animals due to overhunting and habitat loss potentially affects tropical tree populations and carbon cycling. Trees reliant on large-bodied seed dispersers are thought to be particularly negatively affected by defaunation. But besides seed dispersal, defaunation can also increase or decrease seed predation. It remains unclear how these different defaunation effects on early life stages ultimately affect tree population dynamics. We reviewed the literature on how tropical animal loss affects different plant life stages, and we conducted a meta-analysis of how defaunation affects seed predation. We used this information to parameterize models that altered matrix projection models from a suite of tree species to simulate defaunation-caused changes in seed dispersal and predation. We assessed how applying these defaunation effects affected population growth rates. On average, population-level effects of defaunation were negligible, suggesting that defaunation may not cause the massive reductions in forest carbon storage that have been predicted. In contrast to previous hypotheses, we did not detect an effect of seed size on changes in seed predation rates. The change in seed predation did not differ significantly between exclosure experiments and observational studies, although the results of observational studies were far more variable. Although defaunation surely affects certain tree taxa, species that benefit or are harmed by it and net changes in forest carbon storage cannot currently be predicted based on available data. Further research on how factors such as seed predation vary across tree species and defaunation scenarios is necessary for understanding cascading changes in species composition and diversity.
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Affiliation(s)
| | - Jedediah F Brodie
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
- Wildlife Biology Program, University of Montana, Missoula, Montana, USA
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
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18
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Kempel A, Allan E, Gossner MM, Jochum M, Grace JB, Wardle DA. From bottom-up to top-down control of invertebrate herbivores in a retrogressive chronosequence. Ecol Lett 2023; 26:411-424. [PMID: 36688259 DOI: 10.1111/ele.14161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 01/24/2023]
Abstract
In the long-term absence of disturbance, ecosystems often enter a decline or retrogressive phase which leads to reductions in primary productivity, plant biomass, nutrient cycling and foliar quality. However, the consequences of ecosystem retrogression for higher trophic levels such as herbivores and predators, are less clear. Using a post-fire forested island-chronosequence across which retrogression occurs, we provide evidence that nutrient availability strongly controls invertebrate herbivore biomass when predators are few, but that there is a switch from bottom-up to top-down control when predators are common. This trophic flip in herbivore control probably arises because invertebrate predators respond to alternative energy channels from the adjacent aquatic matrix, which were independent of terrestrial plant biomass. Our results suggest that effects of nutrient limitation resulting from ecosystem retrogression on trophic cascades are modified by nutrient-independent variation in predator abundance, and this calls for a more holistic approach to trophic ecology to better understand herbivore effects on plant communities.
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Affiliation(s)
- Anne Kempel
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.,WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland.,Climate Change, Extremes and Natural Hazards in Alpine Regions Research Centre CERC, Davos, Switzerland.,University of Bern, Institute of Plant Sciences, Bern, Switzerland
| | - Eric Allan
- University of Bern, Institute of Plant Sciences, Bern, Switzerland
| | - Martin M Gossner
- Forest Entomology, WSL Swiss Federal Research Institute, Birmensdorf, Switzerland.,ETH Zurich, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, Zurich, Switzerland
| | - Malte Jochum
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.,Leipzig University, Institute of Biology, Leipzig, Germany
| | | | - David A Wardle
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.,Nanyang Technological University, Asian School of the Environment, Singapore, Singapore
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19
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Trophically integrated ecometric models as tools for demonstrating spatial and temporal functional changes in mammal communities. Proc Natl Acad Sci U S A 2023; 120:e2201947120. [PMID: 36745789 PMCID: PMC9963252 DOI: 10.1073/pnas.2201947120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
We are in a modern biodiversity crisis that will restructure community compositions and ecological functions globally. Large mammals, important contributors to ecosystem function, have been affected directly by purposeful extermination and indirectly by climate and land-use changes, yet functional turnover is rarely assessed on a global scale using metrics based on functional traits. Using ecometrics, the study of functional trait distributions and functional turnover, we examine the relationship between vegetation cover and locomotor traits for artiodactyl and carnivoran communities. We show that the ability to detect a functional relationship is strengthened when locomotor traits of both primary consumers (artiodactyls, n = 157 species) and secondary consumers (carnivorans, n = 138 species) are combined into one trophically integrated ecometric model. Overall, locomotor traits of 81% of communities accurately estimate vegetation cover, establishing the advantage of trophically integrated ecometric models over single-group models (58 to 65% correct). We develop an innovative approach within the ecometrics framework, using ecometric anomalies to evaluate mismatches in model estimates and observed values and provide more nuance for understanding relationships between functional traits and vegetation cover. We apply our integrated model to five paleontological sites to illustrate mismatches in the past and today and to demonstrate the utility of the model for paleovegetation interpretations. Observed changes in community traits and their associated vegetations across space and over time demonstrate the strong, rapid effect of environmental filtering on community traits. Ultimately, our trophically integrated ecometric model captures the cascading interactions between taxa, traits, and changing environments.
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20
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Chino H, Mizushima N. ER-Phagy: Quality and Quantity Control of the Endoplasmic Reticulum by Autophagy. Cold Spring Harb Perspect Biol 2023; 15:cshperspect.a041256. [PMID: 35940904 PMCID: PMC9808580 DOI: 10.1101/cshperspect.a041256] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The endoplasmic reticulum (ER) is the largest organelle and has multiple roles in various cellular processes such as protein secretion, lipid synthesis, calcium storage, and organelle biogenesis. The quantity and quality of this organelle are controlled by the ubiquitin-proteasome system and autophagy (termed "ER-phagy"). ER-phagy is defined as the degradation of part of the ER by the vacuole or lysosomes, and there are at least two types of ER-phagy: macro-ER-phagy and micro-ER-phagy. In macro-ER-phagy, ER fragments are enclosed by autophagosomes, which is mediated by ER-phagy receptors. In micro-ER-phagy, a portion of the ER is engulfed directly by the vacuole or lysosomes. In these two pathways, some proteins in the ER lumen can be recognized selectively and subjected to ER-phagy. This review summarizes our current knowledge of ER-phagy, focusing on its membrane dynamics, molecular mechanisms, substrate specificity, and physiological significance.
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Affiliation(s)
- Haruka Chino
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
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21
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Bello C, Schleuning M, Graham CH. Analyzing trophic ecosystem functions with the interaction functional space. Trends Ecol Evol 2023; 38:424-434. [PMID: 36599738 DOI: 10.1016/j.tree.2022.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/18/2022] [Accepted: 12/01/2022] [Indexed: 01/04/2023]
Abstract
Quantifying the vulnerability of ecosystems to global change requires a better understanding of how trophic ecosystem functions emerge. So far, trophic ecosystem functions have been studied from the perspective of either functional diversity or network ecology. To integrate these two perspectives, we propose the interaction functional space (IFS) a conceptual framework to simultaneously analyze the effects of traits and interactions on trophic functions. We exemplify the added value of our framework for seed dispersal and wood decomposition and show how species interactions influence the relationship between functional trait diversity and trophic functions. We propose future applications for a range of functions where the IFS can help to elucidate mechanisms underpinning trophic functions and facilitate understanding of functional changes in ecosystems amidst global change.
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Affiliation(s)
- Carolina Bello
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; Institute of Integrative Biology, ETH Zürich, Universitätstrasse 2, 8092 Zürich, Switzerland.
| | - Matthias Schleuning
- Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Senckenberganlage 25, 60325 Frankfurt, Germany
| | - Catherine H Graham
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
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22
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Wijas BJ, Finlayson G, Letnic M. Herbivores’ Impacts Cascade Through the Brown Food Web in a Dryland. Ecosystems 2022. [DOI: 10.1007/s10021-022-00810-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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23
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Krause J, Harfoot M, Hoeks S, Anthoni P, Brown C, Rounsevell M, Arneth A. How more sophisticated leaf biomass simulations can increase the realism of modelled animal populations. Ecol Modell 2022. [DOI: 10.1016/j.ecolmodel.2022.110061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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24
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Krishnan A, Osuri AM, Krishnadas M. Small mammals reduce distance dependence and increase seed predation risk in tropical rainforest fragments. Biotropica 2022. [DOI: 10.1111/btp.13137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Aparna Krishnan
- Post‐Graduate Programme in Wildlife Biology and Conservation National Centre for Biological Sciences Bangalore Karnataka India
- Nature Conservation Foundation Mysore Karnataka India
| | | | - Meghna Krishnadas
- Laboratory for Conservation of Endangered Species CSIR – Centre for Cellular and Molecular Biology Hyderabad Telangana India
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25
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Carter NH, Pradhan N, Hengaju K, Sonawane C, Sage AH, Grimm V. Forecasting effects of transport infrastructure on endangered tigers: a tool for conservation planning. PeerJ 2022; 10:e13472. [PMID: 35602904 PMCID: PMC9121866 DOI: 10.7717/peerj.13472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 04/29/2022] [Indexed: 01/14/2023] Open
Abstract
The rapid development of transport infrastructure is a major threat to endangered species worldwide. Roads and railways can increase animal mortality, fragment habitats, and exacerbate other threats to biodiversity. Predictive models that forecast the future impacts to endangered species can guide land-use planning in ways that proactively reduce the negative effects of transport infrastructure. Agent-based models are well suited for predictive scenario testing, yet their application to endangered species conservation is rare. Here, we developed a spatially explicit, agent-based model to forecast the effects of transport infrastructure on an isolated tiger (Panthera tigris) population in Nepal's Chitwan National Park-a global biodiversity hotspot. Specifically, our model evaluated the independent and interactive effects of two mechanisms by which transport infrastructure may affect tigers: (a) increasing tiger mortality, e.g., via collisions with vehicles, and (b) depleting prey near infrastructure. We projected potential impacts on tiger population dynamics based on the: (i) existing transportation network in and near the park, and (ii) the inclusion of a proposed railway intersecting through the park's buffer zone. Our model predicted that existing roads would kill 46 tigers over 20 years via increased mortality, and reduced the adult tiger population by 39% (133 to 81). Adding the proposed railway directly killed 10 more tigers over those 20 years; deaths that reduced the overall tiger population by 30 more individuals (81 to 51). Road-induced mortality also decreased the proportion of time a tiger occupied a given site by 5 years in the 20-year simulation. Interestingly, we found that transportation-induced depletion of prey decreased tiger occupancy by nearly 20% in sites close to roads and the railway, thereby reducing tiger exposure to transportation-induced mortality. The results of our model constitute a strong argument for taking into account prey distributions into the planning of roads and railways. Our model can promote tiger-friendly transportation development, for example, by improving Environmental Impact Assessments, identifying "no go" zones where transport infrastructure should be prohibited, and recommending alternative placement of roads and railways.
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Affiliation(s)
- Neil H. Carter
- University of Michigan, Ann Arbor, United States of America
| | - Narendra Pradhan
- International Union for Conservation of Nature, Kathmandu, Nepal
| | - Krishna Hengaju
- International Union for Conservation of Nature, Kathmandu, Nepal
| | | | - Abigail H. Sage
- US Fish and Wildlife Service, Wenatchee, United States of America
| | - Volker Grimm
- Helmholtz Centre for Environmental Research –UFZ, Leipzig, Germany
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26
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Kerby JT, Krivak-Tetley FE, Shikesho SD, Bolger DT. Livestock impacts on an iconic Namib Desert plant are mediated by abiotic conditions. Oecologia 2022; 199:229-242. [PMID: 35524862 PMCID: PMC9120118 DOI: 10.1007/s00442-022-05177-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 03/30/2022] [Indexed: 11/29/2022]
Abstract
Resolving the relative contributions of top-down versus bottom-up drivers of vegetation dynamics is a major challenge in drylands. In the coming decades, growing livestock populations and shifts in water availability will simultaneously impact many arid systems, but a lack of empirical data on plant responses to these pressures limits understanding of how plants will respond. Here, we combine ground and drone observations from an herbivore exclosure experiment to identify ungulate visitation patterns and their impacts on the cover and melon production of !nara (Acanthosicyos horridus), a large, long-lived desert plant in the hyper-arid Namib Desert. !Nara are of key ecological, social, and economic importance to Namib ecosystems and to the local Topnaar people. At our study site, we find that among native and domestic herbivores, free-ranging donkeys have the largest impact on !nara cover and melon production. !Nara cover was negatively affected by herbivores close to the desert-ephemeral river ecotone during a dry period, whereas !nara cover increased on all plants across the landscape during a wetter period, regardless of herbivore access. !Nara near the river channel and those protected from herbivores had more mature melons, particularly during the wetter period. At this site, the potential for conflict between Topnaar !nara melon harvesting and pastoral practices varies with a plant’s distance from the river and prevailing abiotic conditions. This work advances monitoring approaches and adds empirical support to the understanding that top-down and bottom-up regulation of plant dynamics varies with spatiotemporal context, even within landscapes.
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Affiliation(s)
- Jeffrey T Kerby
- Aarhus Institute of Advanced Studies, Aarhus University, Høegh-Guldbergs Gade 6B, 8000, Aarhus C, Denmark. .,Department of Environmental Studies, Dartmouth College, Hanover, NH, 03755, USA.
| | - Flora E Krivak-Tetley
- Department of Environmental Studies, Dartmouth College, Hanover, NH, 03755, USA.,Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Saima D Shikesho
- Gobabeb-Namib Research Institute, Namib Naukluft Park, Namibia.,Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Douglas T Bolger
- Department of Environmental Studies, Dartmouth College, Hanover, NH, 03755, USA
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27
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Beguin J, Côté SD, Vellend M. Large herbivores trigger spatiotemporal changes in forest plant diversity. Ecology 2022; 103:e3739. [PMID: 35488368 DOI: 10.1002/ecy.3739] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 11/06/2022]
Abstract
Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale-dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (Odocoileus virginianus) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided a rare opportunity to test whether deer herbivory represents a direct filter on plant communities or if it mainly acts to suppress dominant plants which, in turn, release other plant species from strong negative plant-plant interactions. These two hypotheses make different predictions about changes in community composition, alpha and beta diversity in different vegetation layers and at different spatial scales. Our results showed that deer had strong effects on plant community composition and successional trajectories, but the resulting impacts on plant alpha and beta diversity patterns were markedly scale-dependent in both time and space. Responses of tree and non-tree vegetation layers were strongly asymmetric. Deer acted both as a direct filter and as a suppressor of dominant plant species during early forest succession, but the magnitude of both processes was specific to tree and non-tree vegetation layers. Although our data supported the ungulate-driven homogenization hypothesis, compositional shifts and changes of alpha diversity were poor predictors of beta diversity loss. Our findings underscore the importance of long-term studies in revealing non-linear temporal community trends, and they challenge managers to prioritize particular community properties and scales of interest, given contrasting trends of composition, alpha, and beta diversity across spatial scales.
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Affiliation(s)
- Julien Beguin
- Département de biologie, Centre d'études nordiques & Chaire de recherche industrielle CRSNG en aménagement intégré des ressources de l'île d'Anticosti, Université Laval, Québec, Québec, Canada.,Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada.,Institut de recherche sur les forêts, Université du Québec en Abitibi-Temiscamingue, 445 boul. de l'Université, Rouyn-Noranda, Québec, Canada
| | - Steeve D Côté
- Département de biologie, Centre d'études nordiques & Chaire de recherche industrielle CRSNG en aménagement intégré des ressources de l'île d'Anticosti, Université Laval, Québec, Québec, Canada
| | - Mark Vellend
- Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
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28
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Szefer P, Molem K, Sau A, Novotny V. Weak effects of birds, bats, and ants on their arthropod prey on pioneering tropical forest gap vegetation. Ecology 2022; 103:e3690. [PMID: 35322403 DOI: 10.1002/ecy.3690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 12/18/2021] [Accepted: 01/18/2022] [Indexed: 11/11/2022]
Abstract
The relative roles of plants competing for resources versus top-down control of vegetation by herbivores, in turn impacted by predators, during early stages of tropical forest succession remain poorly understood. Here we examine the impact of insectivorous birds, bats and ants exclusion on arthropods communities on replicated 5x5 m of pioneering early successional vegetation plots in lowland tropical forest gaps in Papua New Guinea. In plots from which focal taxa of predators were excluded we observed increased biomass of herbivorous and predatory arthropods, and increased density, and decreased diversity of herbivorous insects. However, changes in the biomass of plants, herbivores and arthropod predators were positively correlated or uncorrelated between these three trophic levels and also between individual arthropod orders. Arthropod abundance and biomass correlated strongly with the plant biomass irrespective of the arthropods' trophic position - a signal of bottom-up control. Patterns in herbivore specialization confirm lack of a strong top-down control and were largely unaffected by the exclusion of insectivorous birds, bats and ants. No changes of plant-herbivore interaction networks were detected except for decrease in modularity of the exclosure plots. Our results suggest weak top-down control of herbivores, limited compensation between arthropod and vertebrate predators, and limited intra-guild predation by birds, bats and ants. Possible explanations are strong bottom-up control, a low activity of the higher order predators, especially birds, possibly also bats, in gaps, and continuous influx of herbivores from surrounding mature forest matrix.
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Affiliation(s)
- Piotr Szefer
- Faculty of Science, University of South Bohemia, Branišovská 1645/31a, České Budějovice, Czech Republic.,Biology Centre, Institute of Entomology, Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
| | - Kenneth Molem
- New Guinea Binatang Research Centre, PO Box 604, Madang 511, Papua New Guinea
| | - Austin Sau
- New Guinea Binatang Research Centre, PO Box 604, Madang 511, Papua New Guinea
| | - Vojtech Novotny
- Faculty of Science, University of South Bohemia, Branišovská 1645/31a, České Budějovice, Czech Republic.,Biology Centre, Institute of Entomology, Czech Academy of Sciences, Branišovská 31, České Budějovice, Czech Republic
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29
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30
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Rastetter EB, Griffin KL, Rowe RJ, Gough L, McLaren JR, Boelman NT. Model responses to CO 2 and warming are underestimated without explicit representation of Arctic small-mammal grazing. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e02478. [PMID: 34657358 PMCID: PMC9285540 DOI: 10.1002/eap.2478] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/25/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
We use a simple model of coupled carbon and nitrogen cycles in terrestrial ecosystems to examine how "explicitly representing grazers" vs. "having grazer effects implicitly aggregated in with other biogeochemical processes in the model" alters predicted responses to elevated carbon dioxide and warming. The aggregated approach can affect model predictions because grazer-mediated processes can respond differently to changes in climate compared with the processes with which they are typically aggregated. We use small-mammal grazers in a tundra as an example and find that the typical three-to-four-year cycling frequency is too fast for the effects of cycle peaks and troughs to be fully manifested in the ecosystem biogeochemistry. We conclude that implicitly aggregating the effects of small-mammal grazers with other processes results in an underestimation of ecosystem response to climate change, relative to estimations in which the grazer effects are explicitly represented. The magnitude of this underestimation increases with grazer density. We therefore recommend that grazing effects be incorporated explicitly when applying models of ecosystem response to global change.
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Affiliation(s)
- Edward B. Rastetter
- The Ecosystems CenterMarine Biological LaboratoryWoods HoleMassachusetts02543USA
| | - Kevin L. Griffin
- Department of Ecology, Evolution and Environmental BiologyColumbia UniversityNew YorkNew York10027USA
- Department of Earth and Environmental SciencesColumbia UniversityPalisadesNew York10964USA
- Lamont‐Doherty Earth ObservatoryColumbia UniversityPalisadesNew York10964USA
| | - Rebecca J. Rowe
- Natural Resources and the EnvironmentUniversity of New HampshireDurhamNew Hampshire03824USA
| | - Laura Gough
- Department of Biological SciencesTowson UniversityTowsonMaryland21252USA
| | - Jennie R. McLaren
- Department of Biological SciencesUniversity of Texas at El PasoEl PasoTexas79968USA
| | - Natalie T. Boelman
- Lamont‐Doherty Earth ObservatoryColumbia UniversityPalisadesNew York10964USA
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31
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32
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Karp AT, Faith JT, Marlon JR, Staver AC. Global response of fire activity to late Quaternary grazer extinctions. Science 2021; 374:1145-1148. [PMID: 34822271 DOI: 10.1126/science.abj1580] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Allison T Karp
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - J Tyler Faith
- Natural History Museum of Utah, University of Utah, Salt Lake City, UT, USA.,Department of Anthropology, University of Utah, Salt Lake City, UT, USA.,Origins Centre, University of the Witwatersrand, Johannesburg, South Africa
| | | | - A Carla Staver
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA.,Yale Institute for Biospheric Studies, Yale University, New Haven, CT, USA
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33
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Villar N, Medici EP. Large wild herbivores slow down the rapid decline of plant diversity in a tropical forest biodiversity hotspot. J Appl Ecol 2021. [DOI: 10.1111/1365-2664.14054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nacho Villar
- Department of Aquatic Ecology Netherlands Institute of Ecology Wageningen The Netherlands
| | - Emília Patrícia Medici
- Lowland Tapir Conservation Initiative Institute for Ecological Research Campo Grande Brazil
- School of Environmental Conservation and Sustainability Nazaré Paulista Brazil
- International Union for Conservation of Nature Species Survival CommissionTapir Specialist Group Campo Grande Brazil
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34
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Titcomb GC, Amooni G, Mantas JN, Young HS. The effects of herbivore aggregations at water sources on savanna plants differ across soil and climate gradients. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02422. [PMID: 34288228 DOI: 10.1002/eap.2422] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/29/2021] [Accepted: 03/22/2021] [Indexed: 06/13/2023]
Abstract
Water sources in arid and semiarid ecosystems support humans, wildlife, and domestic animals, forming nodes of activity that sculpt surrounding plant communities and impact critical grazing and soil systems. However, global aridification and changing surface water supply threaten to disrupt these water resources, with strong implications for conservation and management of these ecosystems. To understand how effects of herbivore aggregation at water impact plant communities across contexts, we measured herbivore activity, plant height, cover (trees, grasses, forbs, and bare ground), diversity, and composition at 17 paired water sources and matrix sites across a range of abiotic factors in a semiarid savanna in Kenya. The effects of proximity to surface water and herbivore aggregation on plant communities varied substantially depending on soil and rainfall. In arid areas with nutrient-poor sandy soils, forb and tree cover were 50% lower at water sources compared to neighboring matrix sites, bare ground was 20% higher, species richness was 15% lower, and a single globally important grazing grass (Cynodon dactylon) dominated 60% of transects. However, in mesic areas with nutrient-rich finely textured soils, species richness was 25% higher, despite a 40% increase in bare ground, concurrent with the decline of a dominant tall grass (Themeda triandra) and increase in C. dactylon and other grass species near water sources. Recent rainfall was important for grasses; cover was higher relative to matrix sites only during wet periods, a potential indication of compensatory grazing. These findings suggest that effects of herbivore aggregation on vegetation diversity and composition will vary in magnitude, and in some cases direction, depending on other factors at the site. Where moisture and nutrient resources are high and promote the dominance of few plant species, herbivore aggregations may maintain diversity by promoting grazing lawns and increasing nondominant species cover. However, in arid conditions and sites with low nutrient availability, diversity can be substantially reduced by these aggregations. Our results highlight the importance of considering abiotic conditions when managing for effects of herbivore aggregations near water. This will be particularly important for future managers in light of growing global aridification and surface water changes.
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Affiliation(s)
- Georgia C Titcomb
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, 93106, USA
- Mpala Research Centre, Box 555, Nanyuki, 10400, Kenya
| | | | | | - Hillary S Young
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, 93106, USA
- Mpala Research Centre, Box 555, Nanyuki, 10400, Kenya
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35
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Large Mammalian Herbivores and the Paradox of Soil Carbon in Grazing Ecosystems: Role of Microbial Decomposers and Their Enzymes. Ecosystems 2021. [DOI: 10.1007/s10021-021-00696-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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36
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Zvereva EL, Kozlov MV. Latitudinal gradient in the intensity of biotic interactions in terrestrial ecosystems: Sources of variation and differences from the diversity gradient revealed by meta-analysis. Ecol Lett 2021; 24:2506-2520. [PMID: 34322961 DOI: 10.1111/ele.13851] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/09/2021] [Accepted: 06/14/2021] [Indexed: 01/19/2023]
Abstract
The Latitudinal Biotic Interaction Hypothesis (LBIH) states that the intensity of biotic interactions increases from high to low latitudes. This hypothesis, which may partly explain latitudinal gradients in biodiversity, remains hotly debated, largely due to variable outcomes of published studies. We used meta-analysis to identify the scope of the LBIH in terrestrial ecosystems. For this purpose, we explored the sources of variation in the strength of latitudinal changes in herbivory, carnivory and parasitism (119 publications) and compared these gradients with gradients in the diversity of the respective groups of animals (102 publications). Overall, both herbivory and carnivory decreased towards the poles, while parasitism increased. The latitudinal gradient in herbivory and carnivory was threefold stronger above 50-60° than at lower latitudes and was significant due to interactions involving ectothermic consumers, studies using standardised prey (i.e. prey lacking local anti-predator adaptations) and studies aimed at testing LBIH. The poleward decrease in biodiversity did not differ between ectothermic and endothermic animals or among climate zones and was fourfold stronger than decrease in herbivory and carnivory. The discovered differences between the gradients in biotic interactions and biodiversity suggest that these two global macroecological patterns are likely shaped by different factors.
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37
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Potter AB, Ali Imron M, Pudyatmoko S, Hutchinson MC. Short-term plant-community responses to large mammalian herbivore exclusion in a rewilded Javan savanna. PLoS One 2021; 16:e0255056. [PMID: 34293065 PMCID: PMC8297766 DOI: 10.1371/journal.pone.0255056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 07/08/2021] [Indexed: 11/19/2022] Open
Abstract
Grassy biomes such as savannas are maintained by an interacting suite of ecosystem processes from herbivory to rainfall to fire. Many studies have examined the impacts of large mammalian herbivores on herbaceous plant communities, but few of these studies have been conducted in humid, fertile savannas. We present the findings of a short-term experiment that investigated the effects of herbivory in a fertile, humid, and semi-managed savanna. We erected large-herbivore exclosures in Alas Purwo National Park, Java, Indonesia where rainfall is high and fire is suppressed to test how herbivores impact plant community development across the growing season. Where large mammalian herbivores were excluded, herbaceous plant communities contained more non-grasses and were less similar; diverging in their composition as the growing season progressed. Effects of herbivore exclusion on plant species richness, evenness, and biomass per quadrat were generally weak. Notably, however, two weedy plant species (one native, Imperata cylindrica and one introduced, Senna cf. tora) appeared to benefit most from herbivore release. Our results suggest that heavy grazing pressure by native large mammalian herbivores controlled the composition of the herbaceous plant community. Moreover, exclusion of large mammalian herbivores led to divergence in the plant species composition of exclosures; compositional dissimilarity between herbivore-exclusion plots was higher than between plots exposed to large mammalian herbivores. Our findings suggest that, at this high-rainfall site, large mammalian herbivores constrained the developmental trajectory of plant communities across the growing season.
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Affiliation(s)
- Arjun B. Potter
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
| | - Muhammad Ali Imron
- Wildlife Laboratory, Faculty of Forestry, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Satyawan Pudyatmoko
- Wildlife Laboratory, Faculty of Forestry, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Matthew C. Hutchinson
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
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38
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Su H, Feng Y, Chen J, Chen J, Ma S, Fang J, Xie P. Determinants of trophic cascade strength in freshwater ecosystems: a global analysis. Ecology 2021; 102:e03370. [PMID: 33961286 DOI: 10.1002/ecy.3370] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 01/24/2021] [Accepted: 02/22/2021] [Indexed: 11/08/2022]
Abstract
Top-down cascade effects are among the most important mechanisms underlying community structure and abundance dynamics in aquatic and terrestrial ecosystems worldwide. A current challenge is understanding the factors controlling trophic cascade strength under global environmental changes. Here, we synthesized 161 global sites to analyze how multiple factors influence consumer-resource interactions with fish in freshwater ecosystems. Fish have a profound negative effect on zooplankton and water clarity but positive effects on primary producers and water nutrients. Furthermore, fish trophic levels can modify the strength of trophic cascades, but an even number of food chain length does not have a negative effect on primary producers in real ecosystems. Eutrophication, warming, and predator abundance strengthen the trophic cascade effects on phytoplankton, suggesting that top-down control will be increasingly important under future global environmental changes. We found no influence or even an increasing trophic cascade strength (e.g., phytoplankton) with increasing latitude, which does not support the widespread view that the trophic cascade strength increases closer to the equator. With increasing temporal and spatial scales, the experimental duration has an accumulative effect, whereas the experimental size is not associated with the trophic cascade strength. Taken together, eutrophication, warming, temporal scale, and predator trophic level and abundance are pivotal to understanding the impacts of multiple environmental factors on the trophic cascade strength. Future studies should stress the possible synergistic effect of multiple factors on the food web structure and dynamics.
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Affiliation(s)
- Haojie Su
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Yuhao Feng
- Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Jianfeng Chen
- Poyang Lake Eco-economy Research Center, Jiujiang University, Jiujiang, 332005, China
| | - Jun Chen
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Suhui Ma
- Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Jingyun Fang
- Institute of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Ping Xie
- Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.,Institute for Ecological Research and Pollution Control of Plateau Lakes, School of Ecology and Environmental Science, Yunnan University, Kunming, 650091, China
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39
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Welti EAR, Kaspari M. Sodium addition increases leaf herbivory and fungal damage across four grasslands. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13796] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Ellen A. R. Welti
- Geographical Ecology Group Department of Biology University of Oklahoma Norman OK USA
- Senckenberg Research Institute and Natural History Museum Frankfurt Gelnhausen Germany
| | - Michael Kaspari
- Geographical Ecology Group Department of Biology University of Oklahoma Norman OK USA
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40
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Zhang L, Lan S, Angelini C, Yi H, Zhao L, Chen L, Han G. Interactive effects of crab herbivory and spring drought on a Phragmites australis-dominated salt marsh in the Yellow River Delta. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 766:144254. [PMID: 33421778 DOI: 10.1016/j.scitotenv.2020.144254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 05/17/2023]
Abstract
Consumers are often overlooked as key drivers of vegetation structure and ecosystem functioning in coastal wetlands. This oversight is particularly apparent in Asia, where much of the variation in coastal wetland plant growth and composition is attributed to physical stress gradients. To address this knowledge gap and quantify the relative importance of consumers in Asian coastal wetlands across temporal variation in environmental stress, we conducted a two-year experiment spanning relatively spring wet (2018) and spring dry (2019) years in which we manipulated the presence of the numerically dominant herbivorous crab, Helice tientsinensis, and evaluated its effects on Phragmites australis growth and structure in a Yellow River Delta salt marsh. In spring wetter 2018, Phragmites biomass and stem density were 75% and 34% higher in Crab Exclusion relative to Ambient Crab plots. In 2019 which experienced spring drought and elevated soil salinity, Phragmites biomass and stem density remained similarly high relative to 2018 in Crab Exclusion plots, but fell further, to only 16% and 39% of levels of 2018 observed in Ambient Crab plots. Phragmites' inflorescences density was also significantly reduced in Ambient Crab than Crab Exclusion plots in 2019. Together, these results highlight the significant role that crab herbivores can play in regulating Phragmites in Yellow River Delta salt marshes and suggest that the magnitude of their top-down control may be amplified, although in a non-additive manner, with spring drought stress in the region.
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Affiliation(s)
- Liwen Zhang
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China; CAS Yellow River Delta Ecological Research Station of Coastal Wetland, YICCAS, Yantai, Shandong 264003, PR China.
| | - Siqun Lan
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; School of Resources and Environmental Engineering, Ludong University, Yantai, Shandong 264025, PR China; Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China; CAS Yellow River Delta Ecological Research Station of Coastal Wetland, YICCAS, Yantai, Shandong 264003, PR China
| | - Christine Angelini
- Department of Environmental Engineering Sciences, Engineering School for Sustainable Infrastructure and Environment, University of Florida, PO Box 116580, Gainesville, FL 32611, USA
| | - Huapeng Yi
- School of Resources and Environmental Engineering, Ludong University, Yantai, Shandong 264025, PR China
| | - Lianjun Zhao
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; School of Resources and Environmental Engineering, Ludong University, Yantai, Shandong 264025, PR China; Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China; CAS Yellow River Delta Ecological Research Station of Coastal Wetland, YICCAS, Yantai, Shandong 264003, PR China
| | - Lin Chen
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; College of Environment and Planning, Liaocheng University, Liaocheng, Shandong 252000, PR China; Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China; CAS Yellow River Delta Ecological Research Station of Coastal Wetland, YICCAS, Yantai, Shandong 264003, PR China
| | - Guangxuan Han
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai, Shandong 264003, PR China; Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong 264003, PR China; CAS Yellow River Delta Ecological Research Station of Coastal Wetland, YICCAS, Yantai, Shandong 264003, PR China.
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41
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Fungi and insects compensate for lost vertebrate seed predation in an experimentally defaunated tropical forest. Nat Commun 2021; 12:1650. [PMID: 33712621 PMCID: PMC7955059 DOI: 10.1038/s41467-021-21978-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/12/2021] [Indexed: 01/31/2023] Open
Abstract
Overhunting reduces important plant-animal interactions such as vertebrate seed dispersal and seed predation, thereby altering plant regeneration and even above-ground biomass. It remains unclear, however, if non-hunted species can compensate for lost vertebrates in defaunated ecosystems. We use a nested exclusion experiment to isolate the effects of different seed enemies in a Bornean rainforest. In four of five tree species, vertebrates kill many seeds (13-66%). Nonetheless, when large mammals are excluded, seed mortality from insects and fungi fully compensates for the lost vertebrate predation, such that defaunation has no effect on seedling establishment. The switch from seed predation by generalist vertebrates to specialist insects and fungi in defaunated systems may alter Janzen-Connell effects and density-dependence in plants. Previous work using simulation models to explore how lost seed dispersal will affect tree species composition and carbon storage may require reevaluation in the context of functional redundancy within complex species interactions networks.
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42
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Song X, Lim JY, Yang J, Luskin MS. When do Janzen-Connell effects matter? A phylogenetic meta-analysis of conspecific negative distance and density dependence experiments. Ecol Lett 2020; 24:608-620. [PMID: 33382527 DOI: 10.1111/ele.13665] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 08/18/2020] [Accepted: 11/25/2020] [Indexed: 12/24/2022]
Abstract
The Janzen-Connell (J-C) hypothesis suggests that specialised natural enemies cause distance- or density-dependent mortality among host plants and is regarded as an important mechanism for species coexistence. However, there remains debate about whether this phenomenon is widespread and how variation is structured across taxa and life stages. We performed the largest meta-analysis of experimental studies conducted under natural settings to date. We found little evidence of distance-dependent or density-dependent mortality when grouping all types of manipulations. Our analysis also reveals very large variation in response among species, with 38.5% of species even showing positive responses to manipulations. However, we found a strong signal of distance-dependent mortality among seedlings but not seed experiments, which we attribute to (a) seedlings sharing susceptible tissues with adults (leaves, wood, roots), (b) seedling enemies having worse dispersal than seed enemies and (c) seedlings having fewer physical and chemical defences than seeds. Both density- and distance-dependent mortality showed large variation within genera and families, suggesting that J-C effects are not strongly phylogenetically conserved. There were no clear trends with latitude, rainfall or study duration. We conclude that J-C effects may not be as pervasive as widely thought. Understanding the variation in J-C effects provides opportunities for new discoveries that will refine our understanding of J-C effects and its role in species coexistence.
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Affiliation(s)
- Xiaoyang Song
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, 666303, China.,Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China
| | - Jun Ying Lim
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Jie Yang
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yunnan, 666303, China.,Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, 666303, China
| | - Matthew Scott Luskin
- School of Biological Sciences, University of Queensland, Brisbane, Qld., 4072, Australia
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43
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Villar N, Paz C, Zipparro V, Nazareth S, Bulascoschi L, Bakker ES, Galetti M. Frugivory underpins the nitrogen cycle. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13707] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nacho Villar
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
- Department of Aquatic Ecology Netherlands Institute of Ecology Wageningen The Netherlands
| | - Claudia Paz
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
| | - Valesca Zipparro
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
| | - Sergio Nazareth
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
| | - Leticia Bulascoschi
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
| | - Elisabeth S. Bakker
- Department of Aquatic Ecology Netherlands Institute of Ecology Wageningen The Netherlands
| | - Mauro Galetti
- Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) São Paulo Brazil
- Department of Biology University of Miami Coral Gables FL USA
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44
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Livingstone SW, Isaac ME, Cadotte MW. Invasive dominance and resident diversity: unpacking the impact of plant invasion on biodiversity and ecosystem function. ECOL MONOGR 2020. [DOI: 10.1002/ecm.1425] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stuart W. Livingstone
- Department of Physical & Environmental Sciences University of Toronto Scarborough Toronto OntarioM1C 1A4Canada
- Department of Ecology & Evolutionary Biology University of Toronto Toronto OntarioM5S 3B2Canada
| | - Marney E. Isaac
- Department of Physical & Environmental Sciences University of Toronto Scarborough Toronto OntarioM1C 1A4Canada
| | - Marc W. Cadotte
- Department of Ecology & Evolutionary Biology University of Toronto Toronto OntarioM5S 3B2Canada
- Department of Biology University of Toronto Scarborough Toronto OntarioM1C 1A4Canada
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45
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Density regulation of co-occurring herbivores via two indirect effects mediated by biomass and non-specific induced plant defenses. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00479-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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46
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Harris SH, Kormann UG, Stokely TD, Verschuyl J, Kroll AJ, Betts MG. Do birds help trees grow? An experimental study of the effects of land-use intensification on avian trophic cascades. Ecology 2020; 101:e03018. [PMID: 32078157 DOI: 10.1002/ecy.3018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 12/26/2019] [Accepted: 01/24/2020] [Indexed: 11/09/2022]
Abstract
By regulating populations of herbivores, predators can indirectly influence plant production. However, the factors influencing the strength of this type of trophic cascade are still unclear. We hypothesized that changes to plant community structure would affect the number of avian predators, thereby mediating cascade strength. Using a 4-yr, blocked, split-plot experiment, we independently manipulated both predators (birds) and plants in an early seral managed forest system in western Oregon, USA, and measured abundance across three trophic levels. We applied herbicides, as a surrogate for land-use intensification, to recently clear-cut stands to establish an experimental gradient in plant abundance and species richness, and excluded birds using 28, 225 m2 exclosures. In total, we counted and identified 94,738 arthropods of 141 families in paired control and bird exclosure plots. On average, insectivorous birds reduced arthropod abundance by 16% and plant damage by 14%, and some well-known pests (e.g., Adelges cooleyi) of crop trees (mostly Pseudotsuga menziesii) in our system were reduced by as much as 30%. However, this effect did not translate into a trophic cascade that increased crop-tree growth in the presence of birds. We experimentally reduced plant abundance and diversity by 67% and 55%, respectively, in the most intensive herbicide treatment in relation to untreated controls, but reduced vegetative resources did not change the strength of the direct effect of birds on arthropods or the indirect effect of birds on plants.
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Affiliation(s)
- Scott H Harris
- Department of Forest Ecosystems & Society, Forest Biodiversity Research Network, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Urs G Kormann
- Swiss Ornithological Institute, Seerose 1, CH-6204, Sempach, Switzerland
| | - Thomas D Stokely
- Department of Forest Ecosystems & Society, Forest Biodiversity Research Network, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Jake Verschuyl
- National Council for Air & Stream Improvement, Anacortes, Washington, 98221, USA
| | - Andrew J Kroll
- Weyerhaeuser, 785 N 42nd Street, Springfield, Oregon, 97478, USA
| | - Matthew G Betts
- Department of Forest Ecosystems & Society, Forest Biodiversity Research Network, Oregon State University, Corvallis, Oregon, 97331, USA
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47
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McShea WJ, Sukmasuang R, Erickson DL, Herrmann V, Ngoprasert D, Bhumpakphan N, Davies SJ. Metabarcoding reveals diet diversity in an ungulate community in Thailand. Biotropica 2019. [DOI: 10.1111/btp.12720] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- William J. McShea
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA
| | - Ronglarp Sukmasuang
- Department of Forest Biology Faculty of Forestry Kasetsart University Bangkok Thailand
| | | | - Valentine Herrmann
- Conservation Ecology Center Smithsonian Conservation Biology Institute Front Royal VA USA
| | - Dusit Ngoprasert
- Conservation Ecology Program King Mongkut's University of Technology Thonburi Thailand
| | - Naris Bhumpakphan
- Department of Forest Biology Faculty of Forestry Kasetsart University Bangkok Thailand
| | - Stuart J. Davies
- ForestGeo Program Smithsonian Tropical Biology Institute Washington DC USA
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48
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Barbosa JM, Pascual-Rico R, Eguia Martínez S, Sánchez-Zapata JA. Ungulates Attenuate the Response of Mediterranean Mountain Vegetation to Climate Oscillations. Ecosystems 2019. [DOI: 10.1007/s10021-019-00449-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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49
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Gardner CJ, Bicknell JE, Baldwin-Cantello W, Struebig MJ, Davies ZG. Quantifying the impacts of defaunation on natural forest regeneration in a global meta-analysis. Nat Commun 2019; 10:4590. [PMID: 31611554 PMCID: PMC6791894 DOI: 10.1038/s41467-019-12539-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/11/2019] [Indexed: 12/02/2022] Open
Abstract
Intact forests provide diverse and irreplaceable ecosystem services that are critical to human well-being, such as carbon storage to mitigate climate change. However, the ecosystem functions that underpin these services are highly dependent on the woody vegetation-animal interactions occurring within forests. While vertebrate defaunation is of growing policy concern, the effects of vertebrate loss on natural forest regeneration have yet to be quantified globally. Here we conduct a meta-analysis to assess the direction and magnitude of defaunation impacts on forests. We demonstrate that real-world defaunation caused by hunting and habitat fragmentation leads to reduced forest regeneration, although manipulation experiments provide contrasting findings. The extirpation of primates and birds cause the greatest declines in forest regeneration, emphasising their key role in maintaining carbon stores, and the need for national and international climate change and conservation strategies to protect forests from defaunation fronts as well as deforestation fronts. The defaunation of vertebrates may disrupt forest functioning through the loss of plant-animal interactions, but impacts on forests remain unquantified. Here the authors show that seed dispersal is a key interaction and defaunation of primates and birds negatively impacts forest regeneration.
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Affiliation(s)
- Charlie J Gardner
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK.
| | - Jake E Bicknell
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
| | | | - Matthew J Struebig
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
| | - Zoe G Davies
- Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
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50
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Thorny Shrubs Limit the Browsing Pressure of Large Herbivores on Tree Regeneration in Temperate Lowland Forested Landscapes. SUSTAINABILITY 2019. [DOI: 10.3390/su11133578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Thorny shrubs are considered as an important driver in the natural development of temperate forest structures, particularly in European lowland forests. We assessed the current role of thorny shrubs in the regeneration of deciduous tree species under heavy browsing pressure in a central European temperate forested landscape. The study’s military training area offered a unique opportunity to investigate the processes in which deciduous tree seedlings grew under thorny shrubs and in the close vicinity of thorny shrubs in a landscape with a high density of large herbivores (red deer and sika deer). We assessed the number of seedlings, species composition, seedling height, and degree of browsing damage, and their relationship to study plots elevation, thorny shrub species, coverage, and height. The regenerated tree seedlings were mostly detected as common ash (Fraxinus excelsior) and wild cherry (Cerasus avium). The species of thorny shrubs were blackthorn (Prunus spinosa), hawthorn (Crataegus sp.), and wild rose (Rosa sp.). We found that the thorny shrubs protected the tree seedlings from browsers to a large extent. However, the effects of thorny shrubs on the tree seedlings' characteristics varied among the shrub species. While results revealed significant effects of hawthorn and wild rose on the tree seedlings' abundance and survival, blackthorn’s negative effect of shading the tree seedlings outweighed its protective role. These results indicated a possible mechanism that enabled the regeneration of deciduous tree species under large herbivore pressure. These results can be applied in the landscape planning and forest management of deciduous tree regeneration and forest restoration in temperate forested lowland landscapes, where high densities of large herbivores (without the presence of large predators) usually occur.
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