1
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Song X, Katabuchi M, Chase JM, Johnson DJ, Zhang W, Deng X, Cao M, Yang J. Drought tolerance and species abundance mediate dry season negative density dependence in a tropical forest. Ecology 2024:e4382. [PMID: 39056489 DOI: 10.1002/ecy.4382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/10/2024] [Accepted: 05/20/2024] [Indexed: 07/28/2024]
Abstract
Conspecific negative density dependence (CNDD) is thought to be a key process in maintaining plant diversity. However, the strength of CNDD is highly variable in space and time as well as among species, and correlates of this variation that might help to understand and explain it remain largely unquantified. Using Bayesian hierarchical models, we took advantage of 10-year seedling monitoring data that were collected annually in every dry and rainy season in a seasonal tropical forest. We quantified the interspecific variation in the strength of CNDD and its temporal variation. We also examined potential correlates of this interspecific and temporal variation, including species functional traits (such as drought-tolerant traits, defense-related traits, and recourse acquisition traits) and species abundances. In the dry season, we found a negative relationship between the density of neighboring conspecific seedlings on seedling survival, while in the rainy season, there was a negative relationship between the density of neighboring conspecific adults on seedling survival. In addition, we found that interspecific variation in CNDD was related to drought-tolerant traits in the dry season but not in the rainy season. Across years, we found that drought-intolerant species suffer less CNDD during the dry seasons that have higher rainfall, whereas drought-tolerant species suffer less CNDD when the dry season has lower rainfall. We also found that rare species suffered stronger CNDD in the dry season. Overall, our study highlights that CNDD is highly variable among species and through time, necessitating a deeper appreciation of the environmental and functional contexts of CNDD and their interactions.
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Affiliation(s)
- Xiaoyang Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Masatoshi Katabuchi
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Jonathan M Chase
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
- Department of Computer Science, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Daniel J Johnson
- School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, Florida, USA
| | - Wenfu Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Xiaobao Deng
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Min Cao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Jie Yang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
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2
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Arnillas CA, Carscadden K. When indices disagree: facing conceptual and practical challenges. Trends Ecol Evol 2024; 39:634-643. [PMID: 38508921 DOI: 10.1016/j.tree.2024.02.001] [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: 08/28/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 03/22/2024]
Abstract
Hypothesis testing requires meaningful ways to quantify biological phenomena and account for alternative mechanisms that could explain the same pattern. Researchers combine experiments, statistics, and indices to account for these confounding mechanisms. Key concepts in ecology and evolution, such as niche breadth (NB) or fitness, can be represented by several indices, which often provide uncorrelated estimates. Is this because the indices use different types of noisy data or because the targeted phenomenon is complex and multidimensional? We discuss implications of these scenarios and propose five steps to aid researchers in identifying and combining indices, experiments, and statistics. Building on prior efforts to construct databases of hypotheses and indices and document assumptions, these steps help provide a formal strategy to reduce self-confirmatory bias.
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Affiliation(s)
- Carlos Alberto Arnillas
- Department of Physical and Environmental Sciences, University of Toronto - Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
| | - Kelly Carscadden
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, 1900 Pleasant Street, Box 334, Boulder, CO 80309, USA
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3
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Magee LJ, LaManna JA, Wolf AT, Howe RW, Lu Y, Valle D, Smith DJB, Bagchi R, Bauman D, Johnson DJ. The unexpected influence of legacy conspecific density dependence. Ecol Lett 2024; 27:e14449. [PMID: 38857318 DOI: 10.1111/ele.14449] [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: 11/13/2023] [Revised: 04/17/2024] [Accepted: 04/18/2024] [Indexed: 06/12/2024]
Abstract
When plants die, neighbours escape competition. Living conspecifics could disproportionately benefit because they are freed from negative intraspecific processes; however, if the negative effects of past conspecific neighbours persist, other species might be advantaged, and diversity might be maintained through legacy effects. We examined legacy effects in a mapped forest by modelling the survival of 37,212 trees of 23 species using four neighbourhood properties: living conspecific, living heterospecific, legacy conspecific (dead conspecifics) and legacy heterospecific densities. Legacy conspecific effects proved nearly four times stronger than living conspecific effects; changes in annual survival associated with legacy conspecific density were 1.5% greater than living conspecific effects. Over 90% of species were negatively impacted by legacy conspecific density, compared to 47% by living conspecific density. Our results emphasize that legacies of trees alter community dynamics, revealing that prior research may have underestimated the strength of density dependent interactions by not considering legacy effects.
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Affiliation(s)
- Lukas J Magee
- School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, Florida, USA
| | - Joseph A LaManna
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Amy T Wolf
- Department of Biology and Natural and Applied Sciences, University of Wisconsin-Green Bay, Green Bay, Wisconsin, USA
| | - Robert W Howe
- Department of Biology and Natural and Applied Sciences, University of Wisconsin-Green Bay, Green Bay, Wisconsin, USA
| | - Yuanming Lu
- Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Denis Valle
- School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, Florida, USA
| | - Daniel J B Smith
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, USA
| | - Robert Bagchi
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - David Bauman
- AMAP, Univ Montpellier, CIRAD, CNRS, IRAE, IRD, Montpellier, France
| | - Daniel J Johnson
- School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, Florida, USA
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4
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LaManna JA. Uncovering drivers of global tree diversity. NATURE PLANTS 2024; 10:701-702. [PMID: 38637695 DOI: 10.1038/s41477-024-01695-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Affiliation(s)
- Joseph A LaManna
- Department of Biological Sciences, Marquette University, Milwaukee, WI, USA.
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5
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Hülsmann L, Chisholm RA, Comita L, Visser MD, de Souza Leite M, Aguilar S, Anderson-Teixeira KJ, Bourg NA, Brockelman WY, Bunyavejchewin S, Castaño N, Chang-Yang CH, Chuyong GB, Clay K, Davies SJ, Duque A, Ediriweera S, Ewango C, Gilbert GS, Holík J, Howe RW, Hubbell SP, Itoh A, Johnson DJ, Kenfack D, Král K, Larson AJ, Lutz JA, Makana JR, Malhi Y, McMahon SM, McShea WJ, Mohamad M, Nasardin M, Nathalang A, Norden N, Oliveira AA, Parmigiani R, Perez R, Phillips RP, Pongpattananurak N, Sun IF, Swanson ME, Tan S, Thomas D, Thompson J, Uriarte M, Wolf AT, Yao TL, Zimmerman JK, Zuleta D, Hartig F. Latitudinal patterns in stabilizing density dependence of forest communities. Nature 2024; 627:564-571. [PMID: 38418889 PMCID: PMC10954553 DOI: 10.1038/s41586-024-07118-4] [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: 11/05/2022] [Accepted: 01/25/2024] [Indexed: 03/02/2024]
Abstract
Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10-12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.
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Affiliation(s)
- Lisa Hülsmann
- Ecosystem Analysis and Simulation (EASI) Lab, University of Bayreuth, Bayreuth, Germany.
- Theoretical Ecology, University of Regensburg, Regensburg, Germany.
- Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.
| | - Ryan A Chisholm
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Liza Comita
- School of the Environment, Yale University, New Haven, CT, USA
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Marco D Visser
- Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands
| | | | - Salomon Aguilar
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Panama City, Panama
| | - Kristina J Anderson-Teixeira
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Panama City, Panama
- Conservation Ecology Center, Smithsonian's National Zoo & Conservation Biology Institute, Front Royal, VA, USA
| | - Norman A Bourg
- Conservation Ecology Center, Smithsonian's National Zoo & Conservation Biology Institute, Front Royal, VA, USA
| | - Warren Y Brockelman
- National Biobank of Thailand (NBT), National Science and Technology Development Agency, Bangkok, Thailand
- Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Sarayudh Bunyavejchewin
- Thai Long Term Forest Ecological Research Project, Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok, Thailand
| | - Nicolas Castaño
- Instituto Amazónico de Investigaciones Científicas Sinchi, Bogotá, Colombia
| | - Chia-Hao Chang-Yang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, Taiwan
| | | | - Keith Clay
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA
| | - Stuart J Davies
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, USA
| | - Alvaro Duque
- Departamento de Ciencias Forestales, Universidad Nacional de Colombia Sede Medellín, Medellín, Colombia
| | - Sisira Ediriweera
- Department of Science and Technology, Uva Wellassa University, Badulla, Sri Lanka
| | | | - Gregory S Gilbert
- Environmental Studies Department, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Jan Holík
- Department of Forest Ecology, Silva Tarouca Research Institute, Brno, Czech Republic
| | - Robert W Howe
- Cofrin Center for Biodiversity, Department of Biology, University of Wisconsin-Green Bay, Green Bay, WI, USA
| | - Stephen P Hubbell
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Akira Itoh
- Graduate School of Science, Osaka Metropolitan University, Osaka, Japan
| | - Daniel J Johnson
- School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL, USA
| | - David Kenfack
- Global Earth Observatory (ForestGEO), Smithsonian Tropical Research Institute, Washington, DC, USA
| | - Kamil Král
- Department of Forest Ecology, Silva Tarouca Research Institute, Brno, Czech Republic
| | - Andrew J Larson
- Department of Forest Management, University of Montana, Missoula, MT, USA
- Wilderness Institute, University of Montana, Missoula, MT, USA
| | - James A Lutz
- Department of Wildland Resources, Utah State University, Logan, UT, USA
| | | | - Yadvinder Malhi
- Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK
| | - Sean M McMahon
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, USA
- Smithsonian Environmental Research Center, Edgewater, MD, USA
| | - William J McShea
- Conservation Ecology Center, Smithsonian's National Zoo & Conservation Biology Institute, Front Royal, VA, USA
| | | | | | - Anuttara Nathalang
- National Biobank of Thailand (NBT), National Science and Technology Development Agency, Bangkok, Thailand
| | - Natalia Norden
- Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, Colombia
| | | | - Renan Parmigiani
- Department of Ecology, University of São Paulo, São Paulo, Brazil
| | - Rolando Perez
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Panama City, Panama
| | | | | | - I-Fang Sun
- Department of Natural Resources and Environmental Studies, National Donghwa University, Hualien, Taiwan
| | - Mark E Swanson
- School of the Environment, Washington State University, Pullman, WA, USA
| | | | - Duncan Thomas
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Jill Thompson
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, UK
| | - Maria Uriarte
- Department of Ecology, Evolution & Environmental Biology, Columbia University, New York, NY, USA
| | - Amy T Wolf
- Department of Biology, University of Wisconsin-Green Bay, Green Bay, WI, USA
| | - Tze Leong Yao
- Forest Research Institute Malaysia, Kepong, Malaysia
| | - Jess K Zimmerman
- Department of Environmental Science, University of Puerto Rico, Rio Piedras, USA
| | - Daniel Zuleta
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, USA
| | - Florian Hartig
- Theoretical Ecology, University of Regensburg, Regensburg, Germany
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6
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Jiang F, Bennett JA, Crawford KM, Heinze J, Pu X, Luo A, Wang Z. Global patterns and drivers of plant-soil microbe interactions. Ecol Lett 2024; 27:e14364. [PMID: 38225803 DOI: 10.1111/ele.14364] [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: 09/13/2023] [Revised: 11/20/2023] [Accepted: 12/01/2023] [Indexed: 01/17/2024]
Abstract
Plant-soil feedback (PSF) is an important mechanism determining plant community dynamics and structure. Understanding the geographic patterns and drivers of PSF is essential for understanding the mechanisms underlying geographic plant diversity patterns. We compiled a large dataset containing 5969 observations of PSF from 202 studies to demonstrate the global patterns and drivers of PSF for woody and non-woody species. Overall, PSF was negative on average and was influenced by plant attributes and environmental settings. Woody species PSFs did not vary with latitude, but non-woody PSFs were more negative at higher latitudes. PSF was consistently more positive with increasing aridity for both woody and non-woody species, likely due to increased mutualistic microbes relative to soil-borne pathogens. These findings were consistent between field and greenhouse experiments, suggesting that PSF variation can be driven by soil legacies from climates. Our findings call for caution to use PSF as an explanation of the latitudinal diversity gradient and highlight that aridity can influence plant community dynamics and structure across broad scales through mediating plant-soil microbe interactions.
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Affiliation(s)
- Feng Jiang
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Jonathan A Bennett
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Kerri M Crawford
- Department of Biology & Biochemistry, University of Houston, Houston, Texas, USA
| | - Johannes Heinze
- Department of Biodiversity, Heinz Sielmann Foundation, Wustermark (OT Elstal), Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - Xucai Pu
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Ao Luo
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing, China
| | - Zhiheng Wang
- Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing, China
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7
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Bruijning M, Metcalf CJE, Visser MD. Closing the gap in the Janzen-Connell hypothesis: What determines pathogen diversity? Ecol Lett 2024; 27:e14316. [PMID: 37787147 DOI: 10.1111/ele.14316] [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: 10/04/2022] [Revised: 09/11/2023] [Accepted: 09/17/2023] [Indexed: 10/04/2023]
Abstract
The high tree diversity in tropical forests has long been a puzzle to ecologists. In the 1970s, Janzen and Connell proposed that tree species (hosts) coexist due to the stabilizing actions of specialized enemies. This Janzen-Connell hypothesis was subsequently supported by theoretical studies. Yet, such studies have taken the presence of specialized pathogens for granted, overlooking that pathogen coexistence also requires an explanation. Moreover, stable ecological coexistence does not necessarily imply evolutionary stability. What are the conditions that allow Janzen-Connell effects to evolve? We link theory from community ecology, evolutionary biology and epidemiology to tackle this question, structuring our approach around five theoretical frameworks. Phenomenological Lotka-Volterra competition models provide the most basic framework, which can be restructured to include (single- or multi-)pathogen dynamics. This ecological foundation can be extended to include pathogen evolution. Hosts, of course, may also evolve, and we introduce a coevolutionary model, showing that host-pathogen coevolution can lead to highly diverse systems. Our work unpacks the assumptions underpinning Janzen-Connell and places theoretical bounds on pathogen and host ecology and evolution. The five theoretical frameworks taken together provide a stronger theoretical basis for Janzen-Connell, delivering a wider lens that can yield important insights into the maintenance of diversity in these increasingly threatened systems.
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Affiliation(s)
- Marjolein Bruijning
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - C Jessica E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Marco D Visser
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
- Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands
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8
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Journé V, Hacket-Pain A, Bogdziewicz M. Evolution of masting in plants is linked to investment in low tissue mortality. Nat Commun 2023; 14:7998. [PMID: 38042862 PMCID: PMC10693562 DOI: 10.1038/s41467-023-43616-1] [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: 04/27/2023] [Accepted: 11/14/2023] [Indexed: 12/04/2023] Open
Abstract
Masting, a variable and synchronized variation in reproductive effort is a prevalent strategy among perennial plants, but the factors leading to interspecific differences in masting remain unclear. Here, we investigate interannual patterns of reproductive investment in 517 species of terrestrial perennial plants, including herbs, graminoids, shrubs, and trees. We place these patterns in the context of the plants' phylogeny, habitat, form and function. Our findings reveal that masting is widespread across the plant phylogeny. Nonetheless, reversion from masting to regular seed production is also common. While interannual variation in seed production is highest in temperate and boreal zones, our analysis controlling for environment and phylogeny indicates that masting is more frequent in species that invest in tissue longevity. Our modeling exposes masting-trait relationships that would otherwise remain hidden and provides large-scale evidence that the costs of delayed reproduction play a significant role in the evolution of variable reproduction in plants.
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Affiliation(s)
- Valentin Journé
- Forest Biology Center, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznan, Poland.
| | - Andrew Hacket-Pain
- Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Michał Bogdziewicz
- Forest Biology Center, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614, Poznan, Poland.
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9
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Iuorio A, Eppinga MB, Baudena M, Veerman F, Rietkerk M, Giannino F. Modelling how negative plant-soil feedbacks across life stages affect the spatial patterning of trees. Sci Rep 2023; 13:19128. [PMID: 37926717 PMCID: PMC10625994 DOI: 10.1038/s41598-023-44867-0] [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: 05/08/2023] [Accepted: 10/12/2023] [Indexed: 11/07/2023] Open
Abstract
In this work, we theoretically explore how litter decomposition processes and soil-borne pathogens contribute to negative plant-soil feedbacks, in particular in transient and stable spatial organisation of tropical forest trees and seedlings known as Janzen-Connell distributions. By considering soil-borne pathogens and autotoxicity both separately and in combination in a phenomenological model, we can study how both factors may affect transient dynamics and emerging Janzen-Connell distributions. We also identify parameter regimes associated with different long-term behaviours. Moreover, we compare how the strength of negative plant-soil feedbacks was mediated by tree germination and growth strategies, using a combination of analytical approaches and numerical simulations. Our interdisciplinary investigation, motivated by an ecological question, allows us to construct important links between local feedbacks, spatial self-organisation, and community assembly. Our model analyses contribute to understanding the drivers of biodiversity in tropical ecosystems, by disentangling the abilities of two potential mechanisms to generate Janzen-Connell distributions. Furthermore, our theoretical results may help guiding future field data analyses by identifying spatial signatures in adult tree and seedling distribution data that may reflect the presence of particular plant-soil feedback mechanisms.
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Affiliation(s)
- Annalisa Iuorio
- Department of Engineering, Centro Direzionale-Isola C4, Parthenope University of Naples, 80143, Naples, Italy.
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern-Platz 1, 1090, Vienna, Austria.
| | - Maarten B Eppinga
- Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Mara Baudena
- Environmental Sciences Group, Copernicus Institute of Sustainable Development, Utrecht University, 3508 TC, Utrecht, The Netherlands
- Institute of Atmospheric Sciences and Climate (CNR-ISAC), National Research Council of Italy, Corso Fiume 4, 10133, Torino, Italy
| | - Frits Veerman
- Mathematical Institute, Leiden University, Niels Bohrweg 1, 2300 RA, Leiden, The Netherlands
| | - Max Rietkerk
- Environmental Sciences Group, Copernicus Institute of Sustainable Development, Utrecht University, 3508 TC, Utrecht, The Netherlands
| | - Francesco Giannino
- Department of Agricultural Sciences, University of Naples Federico II, via Università 100, 80055, Portici, Italy
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10
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Chen Y, McConkey KR, Fan P. Sympatric primate seed dispersers and predators jointly contribute to plant diversity in a subtropical forest. Oecologia 2023; 202:715-727. [PMID: 37553533 DOI: 10.1007/s00442-023-05430-w] [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: 04/15/2023] [Accepted: 07/27/2023] [Indexed: 08/10/2023]
Abstract
Mutualistic and antagonistic plant-animal interactions differentially contribute to the maintenance of species diversity in ecological communities. Although both seed dispersal and predation by fruit-eating animals are recognized as important drivers of plant population dynamics, the mechanisms underlying how seed dispersers and predators jointly affect plant diversity remain largely unexplored. Based on mediating roles of seed size and species abundance, we investigated the effects of seed dispersal and predation by two sympatric primates (Nomascus concolor and Trachypithecus crepusculus) on local plant recruitment in a subtropical forest of China. Over a 26 month period, we confirmed that these primates were functionally distinct: gibbons were legitimate seed dispersers who dispersed seeds of 44 plant species, while langurs were primarily seed predators who destroyed seeds of 48 plant species. Gibbons dispersed medium-seeded species more effectively than small- and large-seeded species, and dispersed more seeds of rare species than common and dominant species. Langurs showed a similar predation rate across different sizes of seeds, but destroyed a large number of seeds from common species. Due to gut passage effects, gibbons significantly shortened the duration of seed germination for 58% of the dispersed species; however, for 54% of species, seed germination rates were reduced significantly. Our study underlined the contrasting contributions of two primate species to local plant recruitment processes. By dispersing rare species and destroying the seeds of common species, both primates might jointly maintain plant species diversity. To maintain healthy ecosystems, the conservation of mammals that play critical functional roles needs to receive further attention.
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Affiliation(s)
- Yuan Chen
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China
- School of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China
| | - Kim R McConkey
- School of Environmental and Geographical Sciences, University of Nottingham Malaysia, 43500, Semenyih, Selangor, Malaysia
| | - Pengfei Fan
- School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
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11
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Bonanomi G, Bobrovskikh A, Cartenì F, Mazzoleni S, Giannino F. Adult conspecific density affects Janzen-Connell patterns by modulating the recruitment exclusion zones. FRONTIERS IN PLANT SCIENCE 2023; 14:1079975. [PMID: 37441185 PMCID: PMC10333542 DOI: 10.3389/fpls.2023.1079975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 04/21/2023] [Indexed: 07/15/2023]
Abstract
Plant-soil negative feedback (NF) is a well-established phenomenon that, by preventing the dominance of a single species, allows species coexistence and promotes the maintenance of biodiversity. At community scale, localized NF may cause the formation of exclusion zones under adult conspecifics leading to Janzen-Connell (JC) distribution. In this study, we explore the connection between adult density, either conspecifics or heterospecifics, on the probability of occurrence of JC distributions. Using an individual-based modelling approach, we simulated the formation of exclusion zones due to the build-up of NF in proximity of conspecific adult plants and assessed the frequency of JC distribution in relation to conspecifics and heterospecifics density ranging from isolated trees to closed forest stands. We found that JC recruitment distribution is very common in the case of an isolated tree when NF was strong and capable to form an exclusion zone under the parent tree. At very low NF intensity, a prevalence of the decreasing pattern was observed because, under such conditions, the inhibitory effect due to the presence of the mother tree was unable to overcome the clustering effect of the seed dispersal kernel. However, if NF is strong the JC frequency suddenly decreases in stands with a continuous conspecific cover likely as a result of progressive expansion of the exclusion zone surrounding all trees in closed forest stands. Finally, our simulations showed that JC distribution should not be frequent in the case of rare species immersed in a matrix of heterospecific adults. Overall, the model shows that a plant suffering from strong NF in monospecific stands can rarely exhibit a recruitment pattern fitting the JC model. Such counterintuitive results would provide the means to reconcile the well-established NF framework with part the forest ecologists' community that is still skeptical towards the JC model. Synthesis Our model highlights the complex interconnection between NF intensity, stand density, and recruitment patterns explaining where and why the JC distribution occurs. Moreover, predicting the occurrence of JC in relation to stand density we clarify the relevance of this ecological phenomenon for future integration in plant community frameworks.
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Affiliation(s)
- Giuliano Bonanomi
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- Task Force of Microbiome Studies, University of Naples Federico II, Naples, Italy
| | - Aleksandr Bobrovskikh
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- Laboratory of Plant Growth Biomechanics, Institute of Cytology and Genetics Siberian Branch of Russian Academy of Sciences (SB RAS), Novosibirsk, Russia
| | - Fabrizio Cartenì
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- Task Force of Computational and Quantitative Biology, University of Naples Federico II, Naples, Italy
| | - Stefano Mazzoleni
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- Task Force of Microbiome Studies, University of Naples Federico II, Naples, Italy
- Task Force of Computational and Quantitative Biology, University of Naples Federico II, Naples, Italy
| | - Francesco Giannino
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- Task Force of Computational and Quantitative Biology, University of Naples Federico II, Naples, Italy
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12
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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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13
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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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14
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Malik N, Edwards D, Freckleton RP. Distance and density dependence in two native Bornean dipterocarp species. Ecol Evol 2023; 13:e10004. [PMID: 37091565 PMCID: PMC10115900 DOI: 10.1002/ece3.10004] [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] [Received: 12/01/2021] [Revised: 03/07/2023] [Accepted: 03/29/2023] [Indexed: 04/25/2023] Open
Abstract
The Janzen-Connell hypothesis proposes that density and distance-dependent mortality generated by specialist natural enemies prevent competitive dominance. Much literature on Janzen-Connell mechanisms comes from the neotropics, and evidence of the role of distance and density-dependence is still relatively sparse. We tested the predictions of the Janzen-Connell hypothesis in a South-East Asian system dominated by mast fruiting species. We hypothesized that seedling survival would decrease with distance and density, seedling growth would increase, and herbivory would decrease, according to the predictions of the Janzen-Connell hypothesis. Experiments were conducted to determine the strength of the Janzen-Connell mechanism by manipulating the density and identity of tree species as a function of the distance from parent trees. Survival of conspecific seedlings was reduced near adult trees of one species, but not another. High densities of seedlings decreased the growth of conspecific seedlings of both species. In both species, herbivory rates decreased with distance in low-density areas. This study indicates that dipterocarp species experienced weak Janzen-Connell effects of distance and density dependence at the growth stage studied. Future studies in this system might focus on earlier life-history stages such as seeds and small seedlings, as well as studying mortality during mast-seeding events.
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Affiliation(s)
- Nazrin Malik
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldSheffieldS10 2TNUK
| | - David Edwards
- Department of Forestry Science & Biodiversity, Faculty of ForestryUniversiti Putra MalaysiaSerdangSelangor43400Malaysia
| | - Robert P. Freckleton
- Department of Forestry Science & Biodiversity, Faculty of ForestryUniversiti Putra MalaysiaSerdangSelangor43400Malaysia
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15
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Tuthill JE, Ortega YK, Pearson DE. Seed Size, Seed Dispersal Traits, and Plant Dispersion Patterns for Native and Introduced Grassland Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:1032. [PMID: 36903896 PMCID: PMC10005497 DOI: 10.3390/plants12051032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/16/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Most terrestrial plants disperse by seeds, yet the relationship between seed mass, seed dispersal traits, and plant dispersion is poorly understood. We quantified seed traits for 48 species of native and introduced plants from the grasslands of western Montana, USA, to investigate the relationships between seed traits and plant dispersion patterns. Additionally, because the linkage between dispersal traits and dispersion patterns might be stronger for actively dispersing species, we compared these patterns between native and introduced plants. Finally, we evaluated the efficacy of trait databases versus locally collected data for examining these questions. We found that seed mass correlated positively with the presence of dispersal adaptations such as pappi and awns, but only for introduced plants, for which larger-seeded species were four times as likely to exhibit dispersal adaptations as smaller-seeded species. This finding suggests that introduced plants with larger seeds may require dispersal adaptations to overcome seed mass limitations and invasion barriers. Notably, larger-seeded exotics also tended to be more widely distributed than their smaller-seeded counterparts, again a pattern that was not apparent for native taxa. These results suggest that the effects of seed traits on plant distribution patterns for expanding populations may be obscured for long-established species by other ecological filters (e.g., competition). Finally, seed masses from databases differed from locally collected data for 77% of the study species. Yet, database seed masses correlated with local estimates and generated similar results. Nonetheless, average seed masses differed up to 500-fold between data sources, suggesting that local data provides more valid results for community-level questions.
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Affiliation(s)
- Jane E. Tuthill
- Division of Biological Sciences, Ecology and Evolution, The University of Montana, Missoula, MT 59801, USA
| | - Yvette K. Ortega
- Rocky Mountain Research Station, United States Forest Service, Missoula, MT 59801, USA
| | - Dean E. Pearson
- Division of Biological Sciences, Ecology and Evolution, The University of Montana, Missoula, MT 59801, USA
- Rocky Mountain Research Station, United States Forest Service, Missoula, MT 59801, USA
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16
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Idbella M, Abd‐ElGawad AM, Mazzoleni S, Bonanomi G. Microclimate, soil chemistry, and microbiota fail to explain
Euphorbia dendroides
Janzen‐Connell
pattern in a shrubland. Ecosphere 2022. [DOI: 10.1002/ecs2.4296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Mohamed Idbella
- Department of Agricultural Sciences University of Naples Federico II Naples Italy
- Laboratory of Biosciences, Faculty of Sciences and Techniques Hassan II University Casablanca Morocco
| | - Ahmed M. Abd‐ElGawad
- Department of Botany, Faculty of Sciences Mansoura University Mansoura Egypt
- Plant Production Department, College of Food and Agriculture Sciences King Saud University Riyadh Saudi Arabia
| | - Stefano Mazzoleni
- Department of Agricultural Sciences University of Naples Federico II Naples Italy
- Task Force on Microbiome Studies University of Naples Federico II Naples Italy
| | - Giuliano Bonanomi
- Department of Agricultural Sciences University of Naples Federico II Naples Italy
- Task Force on Microbiome Studies University of Naples Federico II Naples Italy
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17
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Murphy HT, Bradford MG. The role of big trees and abundant species in driving spatial patterns of species richness in an Australian tropical rainforest. Ecol Evol 2022; 12:e9324. [PMID: 36188495 PMCID: PMC9486822 DOI: 10.1002/ece3.9324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/08/2022] [Accepted: 08/30/2022] [Indexed: 11/10/2022] Open
Affiliation(s)
- Helen T. Murphy
- CSIRO, Australian Tropical Sciences and Innovation Precinct James Cook University Townsville Queensland Australia
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18
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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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19
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Adnan M, Islam W, Gang L, Chen HYH. Advanced research tools for fungal diversity and its impact on forest ecosystem. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:45044-45062. [PMID: 35460003 DOI: 10.1007/s11356-022-20317-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
Fungi are dominant ecological participants in the forest ecosystems, which play a major role in recycling organic matter and channeling nutrients across trophic levels. Fungal populations are shaped by plant communities and environmental parameters, and in turn, fungal communities also impact the forest ecosystem through intrinsic participation of different fungal guilds. Mycorrhizal fungi result in conservation and stability of forest ecosystem, while pathogenic fungi can bring change in forest ecosystem, by replacing the dominant plant species with new or exotic plant species. Saprotrophic fungi, being ecological regulators in the forest ecosystem, convert dead tree logs into reusable constituents and complete the ecological cycles of nitrogen and carbon. However, fungal communities have not been studied in-depth with respect to functional, spatiotemporal, or environmental parameters. Previously, fungal diversity and its role in shaping the forest ecosystem were studied by traditional and laborious cultural methods, which were unable to achieve real-time results and draw a conclusive picture of fungal communities. This review highlights the latest advances in biological methods such as next-generation sequencing and meta'omics for observing fungal diversity in the forest ecosystem, the role of different fungal groups in shaping forest ecosystem, forest productivity, and nutrient cycling at global scales.
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Affiliation(s)
- Muhammad Adnan
- College of Life Sciences and Oceanography, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen, 518060, China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Waqar Islam
- Xinjiang Key Laboratory of Desert Plant Roots Ecology and Vegetation Restoration, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Liu Gang
- College of Life Sciences and Oceanography, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Han Y H Chen
- Faculty of Forestry and the Forest Environment, Lakehead University, 955 Oliver Rd, Thunder Bay, ON, P7B 5E1, Canada.
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20
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Massad TJ, Richards LA, Philbin C, Fumiko Yamaguchi L, Kato MJ, Jeffrey CS, Oliveira C, Ochsenrider K, M de Moraes M, Tepe EJ, Cebrian Torrejon G, Sandivo M, Dyer LA. The chemical ecology of tropical forest diversity: Environmental variation, chemical similarity, herbivory, and richness. Ecology 2022; 103:e3762. [PMID: 35593436 DOI: 10.1002/ecy.3762] [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: 11/23/2021] [Revised: 03/01/2022] [Accepted: 03/18/2022] [Indexed: 11/11/2022]
Abstract
Species richness in tropical forests is correlated with other dimensions of diversity, including the diversity of plant-herbivore interactions and the phytochemical diversity that influences those interactions. Understanding the complexity of plant chemistry and the importance of phytochemical diversity for plant-insect interactions and overall forest richness has been enhanced significantly by the application of metabolomics to natural systems. The present work used proton nuclear magnetic resonance spectroscopy (1 H-NMR) profiling of crude leaf extracts to study phytochemical similarity and diversity among Piper plants growing naturally in the Atlantic Rainforest of Brazil. Spectral profile similarity and chemical diversity were quantified to examine the relationship between metrics of phytochemical diversity, specialist and generalist herbivory, and understory plant richness. Herbivory increased with understory species richness, while generalist herbivory increased and specialist herbivory decreased with the diversity of Piper leaf material available. Specialist herbivory increased when conspecific host plants were more spectroscopically dissimilar. Spectral similarity was lower among individuals of common species, and they were also more spectrally diverse, indicating phytochemical diversity is beneficial to plants. Canopy openness and soil nutrients also influenced chemistry and herbivory. The complex relationships uncovered in this study add information to our growing understanding of the importance of phytochemical diversity for plant-insect interactions and tropical plant species richness.
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Affiliation(s)
- Tara Joy Massad
- Department of Scientific Services, Gorongosa National Park, Sofala, Mozambique.,Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brasil
| | - Lora A Richards
- Department of Biology, Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV, USA.,Hitchcock Center for Chemical Ecology, University of Nevada, Reno, NV, USA
| | - Casey Philbin
- Hitchcock Center for Chemical Ecology, University of Nevada, Reno, NV, USA.,Department of Chemistry, University of Nevada, Reno, NV, USA
| | | | - Massuo J Kato
- Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brasil
| | - Christopher S Jeffrey
- Hitchcock Center for Chemical Ecology, University of Nevada, Reno, NV, USA.,Department of Chemistry, University of Nevada, Reno, NV, USA
| | - Celso Oliveira
- Department of Chemistry, University of Nevada, Reno, NV, USA
| | | | - Marcílio M de Moraes
- Departamento de Química, Universidade Federal Rural de Pernambuco, Pernambuco, Pernambuco, Brasil
| | - Eric J Tepe
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | | | | | - Lee A Dyer
- Department of Biology, Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV, USA.,Hitchcock Center for Chemical Ecology, University of Nevada, Reno, NV, USA
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21
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Carrete M, Hiraldo F, Romero-Vidal P, Blanco G, Hernández-Brito D, Sebastián-González E, Díaz-Luque JA, Tella JL. Worldwide Distribution of Antagonistic-Mutualistic Relationships Between Parrots and Palms. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.790883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Palms, like all plants, show coevolutionary relationships with animals that have been traditionally categorized as mutualistic (seed dispersers and pollinators) or antagonistic (seed predators). This dual perspective, however, has prevented a full understanding of their true interactions with some animal groups, mainly those that do not ingest entire fruits. One clear example is parrots, which have been described to use palm species as feeding resources, while their role as seed dispersers has been largely neglected. Here, we combined fieldwork data with information from the literature and citizen science (i.e., naturalists and nature photographers) on parrot foraging ecology worldwide to evaluate the spatial and taxonomic extent of parrot-palm interactions and to identify the eco-evolutionary factors involved. We identified 1,189 interactions between 135 parrots and 107 palm species in more than 50 countries across the six realms where palms are present as natives or introduced. Combining this information, we identified 427 unique parrot-palm interacting pairs (i.e., a parrot species interacting with a palm species). Pure antagonistic interactions (i.e., parrots just preying on seeds or eating or destroying their non-reproductive parts) were less common (5%) than mutualistic ones (i.e., parrots benefiting by partially preying on the seed or fruit or consuming the pulp of the fruit or the flower but also contributing to seed dispersal and, potentially, pollination; 89%). After controlling for phylogeny, the size of consumed seeds and parrot body mass were positively related. Seed dispersal distances varied among palm species (range of estimated median dispersal distances: 9–250 m), with larger parrots dispersing seeds at greater distances, especially large fruits commonly categorized as megafauna anachronisms (>4 cm length). Although parrot-palm interactions are widespread, several factors (e.g., social behavior, predation fear, food availability, or seasonality) may affect the actual position of parrots on the antagonism-mutualism continuum for different palm species and regions, deserving further research. Meanwhile, the pervasiveness of parrot-palm mutualistic interactions, mainly involving seed dispersal and pollination, should not be overlooked in studies of palm ecology and evolution.
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22
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Smith DJB. The functional form of specialised predation affects whether Janzen-Connell effects can prevent competitive exclusion. Ecol Lett 2022; 25:1458-1470. [PMID: 35474601 PMCID: PMC9324109 DOI: 10.1111/ele.14014] [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: 07/12/2021] [Revised: 01/31/2022] [Accepted: 03/24/2022] [Indexed: 11/29/2022]
Abstract
Janzen–Connell effects (JCEs), specialised predation of seeds and seedlings near conspecific trees, are hypothesised to maintain species richness. While previous studies show JCEs can maintain high richness relative to neutral communities, recent theoretical work indicates JCEs may weakly inhibit competitive exclusion when species exhibit interspecific fitness variation. However, recent models make somewhat restrictive assumptions about the functional form of specialised predation—that JCEs occur at a fixed rate when offspring are within a fixed distance of a conspecific tree. Using a theoretical model, I show that the functional form of JCEs largely impacts their ability to maintain coexistence. If predation pressure increases additively with adult tree density and decays exponentially with distance, JCEs maintain considerably higher species richness than predicted by recent models. Loosely parameterising the model with data from a Panamanian tree community, I elucidate the conditions under which JCEs are capable of maintaining high species richness.
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Affiliation(s)
- Daniel J B Smith
- Committee on Evolutionary Biology, University of Chicago, Chicago, Illinois, USA
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23
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LaManna JA, Jones FA, Bell DM, Pabst RJ, Shaw DC. Tree species diversity increases with conspecific negative density dependence across an elevation gradient. Ecol Lett 2022; 25:1237-1249. [PMID: 35291051 DOI: 10.1111/ele.13996] [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: 06/07/2021] [Revised: 01/24/2022] [Accepted: 02/13/2022] [Indexed: 11/30/2022]
Abstract
Elevational and latitudinal gradients in species diversity may be mediated by biotic interactions that cause density-dependent effects of conspecifics on survival or growth to differ from effects of heterospecifics (i.e. conspecific density dependence), but limited evidence exists to support this. We tested the hypothesis that conspecific density dependence varies with elevation using over 40 years of data on tree survival and growth from 23 old-growth temperate forest stands across a 1,000-m elevation gradient. We found that conspecific-density-dependent effects on survival of small-to-intermediate-sized focal trees were negative in lower elevation, higher diversity forest stands typically characterised by warmer temperatures and greater relative humidity. Conspecific-density-dependent effects on survival were less negative in higher elevation stands and ridges than in lower elevation stands and valley bottoms for small-to-intermediate-sized trees, but were neutral for larger trees across elevations. Conspecific-density-dependent effects on growth were negative across all tree size classes and elevations. These findings reveal fundamental differences in biotic interactions that may contribute to relationships between species diversity, elevation and climate.
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Affiliation(s)
- Joseph A LaManna
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - F Andrew Jones
- Department of Botany & Plant Pathology, Oregon State University, Corvallis, Oregon, USA.,Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama
| | - David M Bell
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, Oregon, USA
| | - Robert J Pabst
- Department of Forest Ecosystems & Society, Oregon State University, Corvallis, Oregon, USA
| | - David C Shaw
- Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, Oregon, USA
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24
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Abstract
Masting, or synchronous production of large seed crops, is widespread among plants. The predator satiation hypothesis states that masting evolved to overwhelm seed predators with an excess of food. Yet, this popular explanation faced few rigorous tests. We conducted a meta-analysis of studies that related the magnitude of seed production to the intensity of seed predation. Our results validate certain theoretical notions (e.g., that predator satiation is more effective at higher latitudes) but challenge others (e.g., that specialist and generalist consumers differ in the type of functional response to masting). We also found that masting is losing its ability to satiate consumers, probably because global warming affected masting patterns. This shift might considerably impair the reproduction of masting plants. Predator satiation is the most commonly tested hypothesis that explains the evolutionary advantages of masting. It proposes that masting benefits plant reproduction by reducing the proportion of seed crop that is consumed by predators. This hypothesis is widely accepted, but many theoretical notions about predator satiation have not been subjected to a robust evaluation. To address this issue, we conducted a meta-analysis of studies that quantified seed predation in relation to mast seeding. We found evidence of both numerical (starvation between mast years) and functional (satiation during mast years) response of consumers to masting. These two effects reinforced each other. Masting satiated invertebrate but not vertebrate seed predators. Satiation was more pronounced at higher, temperate, and boreal latitudes, perhaps because masting is more effective in reducing seed losses when plant communities are less diverse. The effectiveness of masting in satiating invertebrate consumers declined over time (1972 to 2018), probably reflecting the impact of climate change on the frequency and intensity of masting. If masting ceases to reduce seed losses, a crucial advantage of this reproductive strategy will be lost, and sustainability of many tree populations will decline.
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Seget B, Bogdziewicz M, Holeksa J, Ledwoń M, Milne-Rostkowska F, Piechnik Ł, Rzepczak A, Żywiec M. Costs and benefits of masting: economies of scale are not reduced by negative density-dependence in seedling survival in Sorbus aucuparia. THE NEW PHYTOLOGIST 2022; 233:1931-1938. [PMID: 34845725 DOI: 10.1111/nph.17887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
Masting is a widespread reproductive strategy in plants that helps to reduce seed predation and increase pollination. However, masting can involve costs, notably negative density-dependent (NDD) seedling survival caused by concentrating reproduction in intermittent events. Masting benefits have received widespread attention, but the costs are understudied, which precludes understanding why some plant species have evolved intense masting, while others reproduce regularly. We followed seed production, seed predation (both 13 yr), and seedling recruitment and survival (11 yr) in Sorbus aucuparia. We tested whether NDD in seedling survival after mast years can reduce the benefits of pulsed reproduction that come through predator satiation. Seed predation rates were extreme in our population (mean = 75%), but were reduced by masting. The commonly accepted, but untested, assertion that pulsed recruitment is associated with strong NDD was unsupported. Consequently, the proportion of seedlings that survived their first year increased with fruit production. This provides a rare test of economies of scale beyond the seed stage. Our results provide estimation of the costs of mast seeding, and indicate that these may be lower than expected. Low masting costs, if common, may help explain why masting is such a widespread reproductive strategy throughout the plant kingdom.
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Affiliation(s)
- Barbara Seget
- W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, Kraków, 31-512, Poland
| | - Michał Bogdziewicz
- Department of Systematic Zoology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznań, 61-614, Poland
- INRAE, LESSEM, University Grenoble Alpes, 2 rue de la Papeterie, BP 76, Saint-Martin-d'Hères, 38400, France
| | - Jan Holeksa
- Department of Plant Ecology and Environmental Protection, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznań, 61-614, Poland
| | - Mateusz Ledwoń
- Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, Kraków, 31-016, Poland
| | - Fiona Milne-Rostkowska
- Department of Plant Ecology and Environmental Protection, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, Poznań, 61-614, Poland
| | - Łukasz Piechnik
- W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, Kraków, 31-512, Poland
| | - Alicja Rzepczak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, Poznań, 61-704, Poland
| | - Magdalena Żywiec
- W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, Kraków, 31-512, Poland
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Martini F, Zou C, Song X, Goodale UM. Abiotic Drivers of Seedling Bank Diversity in Subtropical Forests of Southern China. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.784036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abiotic factors are important to shape plant community composition and diversity through processes described as environmental filtering. Most studies on plant diversity in forests focus on adult trees, while the abiotic drivers of forest seedling community characteristics are less understood. Here, we studied seedling banks’ composition, richness, diversity, and abundance, and investigated their relationships with microsite abiotic conditions along a wide elevational gradient. We sampled seedling communities in 312 1-m2 quadrats, distributed in 13 one-ha plots in four subtropical forests in south China, covering an elevation gradient of 1500 m, for 2 years. We measured light availability, slope, and 11 soil nutrients for each seedling quadrat. We used analysis of similarities and multivariate analysis of variance to compare the composition and abiotic drivers of the four forests’ seedling communities. We then used mixed models and structural equation modeling to test the direct and indirect effects of abiotic factors on seedling species richness, diversity, and abundance. The differences in seedling community composition among these forests were mostly explained by differences in elevations and soil nutrients. Seedling diversity as Shannon and Simpson diversity index decreased with increasing elevation and increased with increasing slope, but seedling abundance and species richness did not. Elevation had an indirect effect on Simpson’s diversity index through modulating the direct effects of soil properties. Our findings show that soil properties play a prominent role in favoring differentiation in species composition among the four forests we studied and provide additional evidence to decreasing species diversity with elevation. However, this was reflected in decreasing Shannon and Simpson indices rather than species richness, which is more commonly studied. Whether and to what extent future environmental changes in climate and soil acidification will alter future forest composition and diversity needs to be investigated.
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O'Brien MJ, Escudero A. Topography in tropical forests enhances growth and survival differences within and among species via water availability and biotic interactions. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13977] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Michael J. O'Brien
- Área de Biodiversidad y Conservación Universidad Rey Juan Carlos Móstoles Spain
- Southeast Asia Rainforest Research Partnership (SEARRP) Kota Kinabalu Sabah Malaysia
| | - Adrián Escudero
- Área de Biodiversidad y Conservación Universidad Rey Juan Carlos Móstoles Spain
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28
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Examining the generality of the biphasic transition from niche-structured to immigration-structured communities. THEOR ECOL-NETH 2021. [DOI: 10.1007/s12080-021-00521-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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29
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Song X, Corlett RT. Do natural enemies mediate conspecific negative distance‐ and density‐dependence of trees? A meta‐analysis of exclusion experiments. OIKOS 2021. [DOI: 10.1111/oik.08509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaoyang Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences Mengla China
| | - Richard T. Corlett
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences Mengla China
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences Mengla China
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Kuyper TW. Networks of friends and foes and the fate of tree seedlings. THE NEW PHYTOLOGIST 2021; 230:1688-1689. [PMID: 33843064 DOI: 10.1111/nph.17337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Thomas W Kuyper
- Soil Biology Group, Wageningen University & Research, PO Box 47, Wageningen, 6700 AA, the Netherlands
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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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Luskin MS, Johnson DJ, Ickes K, Yao TL, Davies SJ. Wildlife disturbances as a source of conspecific negative density-dependent mortality in tropical trees. Proc Biol Sci 2021; 288:20210001. [PMID: 33653133 DOI: 10.1098/rspb.2021.0001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Large vertebrates are rarely considered important drivers of conspecific negative density-dependent mortality (CNDD) in plants because they are generalist consumers. However, disturbances like trampling and nesting also cause plant mortality, and their impact on plant diversity depends on the spatial overlap between wildlife habitat preferences and plant species composition. We studied the impact of native wildlife on a hyperdiverse tree community in Malaysia. Pigs (Sus scrofa) are abnormally abundant at the site due to food subsidies in nearby farmland and they construct birthing nests using hundreds of tree saplings. We tagged 34 950 tree saplings in a 25 ha plot during an initial census and assessed the source mortality by recovering tree tags from pig nests (n = 1672 pig-induced deaths). At the stand scale, pigs nested in flat dry habitats, and at the local neighbourhood scale, they nested within clumps of saplings, both of which are intuitive for safe and efficient nest building. At the stand scale, flat dry habitats contained higher sapling densities and higher proportions of common species, so pig nesting increased the weighted average species evenness across habitats. At the neighbourhood scale, pig-induced sapling mortality was associated with higher heterospecific and especially conspecific sapling densities. Tree species have clumped distributions due to dispersal limitation and habitat filtering, so pig disturbances in sapling clumps indirectly caused CNDD. As a result, Pielou species evenness in 400 m2 quadrats increased 105% more in areas with pig-induced deaths than areas without disturbances. Wildlife induced CNDD and this supported tree species evenness, but they also drove a 62% decline in sapling densities from 1996 to 2010, which is unsustainable. We suspect pig nesting is an important feature shaping tree composition throughout the region.
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Affiliation(s)
- Matthew Scott Luskin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.,Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, USA.,Asian School of the Environment, Nanyang Technological University, Singapore, Singapore
| | - Daniel J Johnson
- School of Forest Resources and Conservation, University of Florida, Gainesville, FL, USA
| | - Kalan Ickes
- Department of Biological Sciences, Clemson University, Clemson, SC, USA
| | - Tze Leong Yao
- Forest Research Institute Malaysia (FRIM), Kepong, Selangor Darul Ehsan, Malaysia
| | - Stuart J Davies
- Forest Global Earth Observatory, Smithsonian Tropical Research Institute, Washington, DC, USA
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