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Nhat PM, Armstrong CW, Bråthen KA, Tuomi M. Controlling the stock or the habitat - The crisis of native invasive encroachment in the grazing land of Norwegian reindeer husbandry. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 370:122457. [PMID: 39260285 DOI: 10.1016/j.jenvman.2024.122457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 09/06/2024] [Accepted: 09/06/2024] [Indexed: 09/13/2024]
Abstract
Climate change negatively impacts reindeer grazing in Fennoscandia, with the encroachment of Empetrum nigrum (crowberry) being a significant, yet largely unrecognized problem. Crowberry encroachment affects the neighboring palatable vegetation negatively, homogenizing the pasture and decreasing ecosystem biodiversity. Current husbandry management aims are based on sustainable use of the pasture land, yet pasture quality is not considered a central indicator. To prevent overgrazing, reindeer numbers are limited, but as the animals avoid crowberry, this invasive species exacerbates the Norwegian reindeer husbandry's pasture crisis. Herders therefore intervene with two adaptive strategies, supplementary feeding and/or crowberry control. We develop a general three-species bioeconomic model with five variants to understand the economic impact of an invasive species on herbivore husbandry, and the net benefits of the two adaptive measures at the steady state. Our analytical results show that the native invasive encroachment causes a decrease in not only the nutrient-high grazing land but also the optimal herbivore herd and slaughter volume. Supplementary feeding is implemented to increase the herd size, yet the measure further depletes the grazing pasture, making this practice unsustainable. Instead, controlling crowberry protects both the grazing pasture and reindeer herd size. Applying this to the Norwegian reindeer husbandry case, we find crowberry control more cost-effective and less stressful for the pasture land than supplementary feeding. Government subsidies are shown to be essential for restoring herd sizes to the status quo.
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Affiliation(s)
- Pham M Nhat
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, 9019, Tromsø, Norway.
| | - Claire W Armstrong
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Kari Anne Bråthen
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Maria Tuomi
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, 9019, Tromsø, Norway
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Lortie CJ, Brown C, Haas-Desmarais S, Lucero J, Callaway R, Braun J, Filazzola A. Plant networks are more connected by invasive brome and native shrub facilitation in Central California drylands. Sci Rep 2024; 14:8958. [PMID: 38637667 PMCID: PMC11026385 DOI: 10.1038/s41598-024-59868-w] [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: 06/05/2023] [Accepted: 04/15/2024] [Indexed: 04/20/2024] Open
Abstract
Dominant vegetation in many ecosystems is an integral component of structure and habitat. In many drylands, native shrubs function as foundation species that benefit other plants and animals. However, invasive exotic plant species can comprise a significant proportion of the vegetation. In Central California drylands, the facilitative shrub Ephedra californica and the invasive Bromus rubens are widely dispersed and common. Using comprehensive survey data structured by shrub and open gaps for the region, we compared network structure with and without this native shrub canopy and with and without the invasive brome. The presence of the invasive brome profoundly shifted the network measure of centrality in the microsites structured by a shrub canopy (centrality scores increased from 4.3 under shrubs without brome to 6.3, i.e. a relative increase of 42%). This strongly suggests that plant species such as brome can undermine the positive and stabilizing effects of native foundation plant species provided by shrubs in drylands by changing the frequency that the remaining species connect to one another. The net proportion of positive and negative associations was consistent across all microsites (approximately 50% with a total of 14% non-random co-occurrences on average) suggesting that these plant-plant networks are rewired but not more negative. Maintaining resilience in biodiversity thus needs to capitalize on protecting native shrubs whilst also controlling invasive grass species particularly when associated with shrubs.
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Affiliation(s)
- C J Lortie
- Department of Biology, York University, Toronto, ON, M3J1P3, Canada
| | - Charlotte Brown
- Département de Biologie, Université de Sherbrooke, Voie 9, Sherbrooke, Québec, J1K 2R1, Canada
| | | | - Jacob Lucero
- Texas A & M, Department of Rangeland, Wildlife and Fisheries Management, 495 Horticulture Rd #305, College Station, TX, 77843-2183, USA
| | - Ragan Callaway
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Jenna Braun
- Department of Biology, York University, Toronto, ON, M3J1P3, Canada
| | - Alessandro Filazzola
- Apex Resource Management Solutions, Ottawa, ON, Canada.
- Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada.
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3
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Bhatt U, Sharma S, Kumar D, Soni V. Impact of streetlights on physiology, biochemistry and diversity of urban bryophyte: a case study on moss Semibarbula orientalis. JOURNAL OF URBAN ECOLOGY 2022. [DOI: 10.1093/jue/juac019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Abstract
The use of artificial light at night is a very basic symbol of urbanization and has distorted many ecological, biochemical and physiological phenomena in plants, which have settled for millions of years in the biological system. Continuous illumination of light significantly alters the circadian rhythm of all organisms. The present study was focused to understand the effects of continuous light (CL) on the biochemistry and physiology of moss Semibarbula orientalis. It was observed that H2O2 accumulation and activities of chlorophyllase, phenylalanine ammonia-lyase, superoxide dismutase and catalase enzymes significantly enhanced in plants growing under streetlights. Similarly, plants under CL showed a marked reduction in photosynthetic performance. Specific fluxes (ABS/RC, TR/RC, ET/RC), phenomenological fluxes (ABS/CS, TR/CS, ET/CS), density of photosystem-II, quantum yield of photosynthesis and chlorophyll concentration markedly declined in plants growing under streetlights. Depletion in performance indices (PIcs and PIabs) and primary and secondary photochemistry [PHIO/(1 − PHIO) and PSIO/(1 − PSIO)] were also noticed, which indicated failure of adaptive strategies of photosystem-II, resulting in the loss of biomass of S. orientalis. Biomass decline is also shown by a decrease in coverage, which reduces the bryophyte species richness of the chosen locations. Present studies clearly indicate that artificial light at night drastically affects the moss population. The reduction in the dominating species, S. orientalis, improves species evenness and results in a slow growth rate.
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Affiliation(s)
- Upma Bhatt
- Plant Bioenergetics and Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University , Udaipur 313001, Rajasthan, India
| | - Shubhangani Sharma
- Plant Bioenergetics and Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University , Udaipur 313001, Rajasthan, India
| | - Deepak Kumar
- Plant Bioenergetics and Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University , Udaipur 313001, Rajasthan, India
| | - Vineet Soni
- Plant Bioenergetics and Biotechnology Laboratory, Department of Botany, Mohanlal Sukhadia University , Udaipur 313001, Rajasthan, India
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4
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Carlson RR, Evans LJ, Foo SA, Grady BW, Li J, Seeley M, Xu Y, Asner GP. Synergistic benefits of conserving land-sea ecosystems. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01684] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Mörsdorf MA, Ravolainen VT, Yoccoz NG, Thórhallsdóttir TE, Jónsdóttir IS. Decades of Recovery From Sheep Grazing Reveal No Effects on Plant Diversity Patterns Within Icelandic Tundra Landscapes. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2020.602538] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tundra plant communities are often shaped by topography. Contrasting wind exposure, slopes of different inclination and landforms of different curvature affect habitat conditions and shape plant diversity patterns. The majority of tundra is also grazed by ungulates, which may alter topographically induced plant diversity patterns, but such effects may depend on the spatial scales of assessments. Here we ask whether topographically induced patterns of within (alpha) and between (beta) plant community diversity are different in contrasting grazing regimes. We studied plant communities within tundra landscapes that were located in the North and Northwest of Iceland. Half of the studied landscapes were grazed by sheep, whereas the other half was currently un-grazed and recovering for several decades (up to 60 years). Alpha and beta diversity were assessed on explicitly defined, nested spatial scales, which were determined by topographical units. Although we contrasted currently grazed vegetation to vegetation that witnessed several decades of grazing recovery, we found no statistically significant differences in plant diversity patterns. We relate these findings to the low resilience of our study system toward grazing disturbances, which has important implications for management practices in the tundra. Effects of topography on species richness were only found for specific spatial scales of analyses. Species rich topographical units were associated with relatively large biomass of plant growth forms that promote nutrient availability and potential plant productivity in the tundra, such as forbs. This suggests that biomass of such plant growth forms within habitats can be a useful proxy of potential plant productivity and may predict spatial patterns of plant species richness in tundra.
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Gomaa NH, Hegazy AK, Latef AAHA. Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times. PLANTS 2020; 9:plants9121726. [PMID: 33297465 PMCID: PMC7762360 DOI: 10.3390/plants9121726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 11/28/2022]
Abstract
Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.
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Affiliation(s)
- Nasr H. Gomaa
- Department of Botany and Microbiology, Faculty of Science, Beni-Suef University, Beni-Suef 62521, Egypt
- Biology Department, College of Science, Jouf University, P.O. Box 2014, Sakaka 72341, Saudi Arabia
- Correspondence:
| | - Ahmad K. Hegazy
- Department of Botany and Microbiology, Faculty of Science, Cairo University, Giza 12613, Egypt;
| | - Arafat Abdel Hamed Abdel Latef
- Department of Biology, Turabah University College, Turabah Branch, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia;
- Botany and Microbiology Department, Faculty of Science, South Valley University, Qena 83523, Egypt
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Andruko R, Danby R, Grogan P. Recent Growth and Expansion of Birch Shrubs Across a Low Arctic Landscape in Continental Canada: Are These Responses More a Consequence of the Severely Declining Caribou Herd than of Climate Warming? Ecosystems 2020; 23:1362-1379. [PMID: 33214772 PMCID: PMC7666286 DOI: 10.1007/s10021-019-00474-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/08/2019] [Indexed: 12/01/2022]
Abstract
The recent widespread expansion of deciduous shrubs across much of the Arctic has been largely attributed to climate warming. This study investigated decadal growth rates of dwarf birch (Betula glandulosa) across a low Arctic landscape in the continental interior of Canada. Detailed birch cover (100 m2 replicate plots) and individual shrub stature measurement datasets for five representative habitat-types were compared between 2006 and 2016, and evaluated in relation to environmental characteristics. Furthermore, dendrochronologically-based annual growth rates were assessed in relation to the 20-year climate record. Birch height, lateral dimensions, and patch groundcover all increased 20–25% relative to 2006 values, but these increases were similar among the habitat-types. Together, the limited evidence of recent warming at this site, the absence of significant habitat-type growth rate differences, and the lack of correlation between annual climate and stem secondary growth strongly suggest that climate change was not the principal cause. Instead, we propose that release from caribou impacts following the recent severe herd decline may explain the net shrub growth. Individual shrub growth rates were correlated with soil nutrient availability, but the latter was highly variable, suggesting that growth rates are primarily determined by fine-scale rather than habitat-scale spatial heterogeneity in nutrient supply. Together, our results demonstrate that birch growth has been enhanced across a variety of habitat-types in the Daring Lake landscape over the decade since 2006, and suggest that the recent severe caribou herd declines may be at least as significant as climate warming in driving birch shrub expansion in the Canadian central low Arctic.
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Affiliation(s)
- Rhett Andruko
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6 Canada
| | - Ryan Danby
- School of Environmental Studies, Queen's University, Kingston, Ontario K7L 3N6 Canada
| | - Paul Grogan
- Department of Biology, Queen's University, Kingston, Ontario K7L 3N6 Canada
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8
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Pilsbacher AK, Lindgård B, Reiersen R, González VT, Bråthen KA. Interfering with neighbouring communities: Allelopathy astray in the tundra delays seedling development. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Anna Katharina Pilsbacher
- Department of Arctic and Marin Biology UiT – Arctic University of Norway Tromsø Norway
- Department of Language and Culture UiT – Arctic University of Norway Tromsø Norway
| | - Bente Lindgård
- Department of Arctic and Marin Biology UiT – Arctic University of Norway Tromsø Norway
| | - Rigmor Reiersen
- Department of Arctic and Marin Biology UiT – Arctic University of Norway Tromsø Norway
| | - Victoria T. González
- Department of Ecosystems in the Barents region Norwegian institute of Bioeconomy Research‐NIBIO Svanvik Norway
| | - Kari Anne Bråthen
- Department of Arctic and Marin Biology UiT – Arctic University of Norway Tromsø Norway
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9
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Cock MC, Hierro JL. Plant interactions balance under biotic and abiotic stressors: the importance of herbivory in semi-arid ecosystems. Oecologia 2020; 194:685-694. [PMID: 33094382 DOI: 10.1007/s00442-020-04789-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 10/10/2020] [Indexed: 11/28/2022]
Abstract
Biotic and abiotic stressors commonly co-occur in plant communities and influence interactions between plants. However, their combined effects on plant interactions have not been widely studied and are still unclear. Here, we assessed the balance of interactions between neighboring plants along a grazing gradient and under two water regimes. We conducted a three-year-field experiment in semi-arid central Argentina with transplants of the dominant palatable grass Piptochaetium napostaense growing in Baccharis ulicina and open microsites across a gradient of grazing pressure. Additionally, we established a water addition treatment along that gradient. We recorded herbivory, size, and fecundity of P. napostaense. During the first two years, P. napostaense was consumed less and was larger below Baccharis than in the open. These differences were greatest under high grazing pressure. Differences in fecundity between microsites were only detected under high and medium grazing pressure in the first two years. In the third year, Baccharis lost their leaves for unclear reasons and provided poor herbivory protection; hence, P. napostaense plants in Baccharis were larger than those in the open only under medium and low grazing pressure, and there were no differences in fecundity between microsites under any grazing condition. Water additions exerted no effect on plant interactions. The balance of interactions changed from positive under heavy grazing to neutral at low and no grazing and water availability did not alter that balance. We conclude that herbivore pressure is an important driver of the balance of plant interactions in semi-arid environments.
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Affiliation(s)
- Marina C Cock
- Laboratorio de Ecología, Biogeografía y Evolución Vegetal (LEByEV), Instituto de Ciencias de la Tierra y Ambientales de La Pampa (INCITAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional de La Pampa (UNLPam), Mendoza 109, 6300, Santa Rosa, La Pampa, Argentina. .,Departamento de Biología, Facultad de Ciencias Exactas y Naturales, UNLPam, Uruguay 151, 6300, Santa Rosa, La Pampa, Argentina.
| | - José L Hierro
- Laboratorio de Ecología, Biogeografía y Evolución Vegetal (LEByEV), Instituto de Ciencias de la Tierra y Ambientales de La Pampa (INCITAP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional de La Pampa (UNLPam), Mendoza 109, 6300, Santa Rosa, La Pampa, Argentina.,Departamento de Biología, Facultad de Ciencias Exactas y Naturales, UNLPam, Uruguay 151, 6300, Santa Rosa, La Pampa, Argentina
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10
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Bioclimatic gradients and soil property trends from northernmost mainland Norway to the Svalbard archipelago. Does the arctic biome extend into mainland Norway? PLoS One 2020; 15:e0239183. [PMID: 32941518 PMCID: PMC7498165 DOI: 10.1371/journal.pone.0239183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 09/02/2020] [Indexed: 11/19/2022] Open
Abstract
The boundary between the boreal and arctic biomes in northwest Europe has been a
matter of debate for many years. Some authors consider that the boundary is
marked by the northern limit of tree growth in the northernmost Norwegian
mainland. In this study we have collected air and soil temperature data from 37
heath stands from northern Finnmark (71°N), the northernmost part of the
Norwegian mainland, through Bear Island (74°N) in the Barents sea, to
Adventsdalen (78)°N (in Spitsbergen) in Svalbard archipelago. In Finnmark, plots
both south and north of the treeline were investigated. Vegetation and soil
chemistry analyses were performed on the plots in Finnmark and Svalbard.
Significant decreasing south-north trends in air and soil temperatures were
observed from Finnmark to Spitsbergen. Soils in Finnmark were acidic and rich in
organic matter, while those on Adventsdalen were basic and poor in organic
matter. Vegetational analysis identified five communities: three in Finnmark and
two on Adventsdalen. The communities in Finnmark had marked mutual similarities
but were very different from those on Adventsdalen. No significant ecological
differences between heaths south and north of the treeline in Finnmark were
observed. Air and soil temperature variables in Finnmark were outside the
recognized range for the arctic biome and inconsistent with the presence of
permafrost both south and north of the treeline. A major difference between
Finnmark and Spitsbergen was amount of soil frost and length of the growing
season. Our results suggest that the boreal biome extends all the way to the
north coast of mainland Norway; and previously used division of heaths in
Finnmark into boreal, alpine and arctic biomes is not justified.
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Six-year removal of co-dominant grasses alleviated competitive pressure on subdominant grasses but dominant shrub removal had neutral effects in a subalpine ecosystem. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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12
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Molina‐Montenegro MA, Baldelomar M, Atala C, Torres‐Díaz C. A tradeoff between fitness‐related traits mask facilitation in a semiarid ecosystem. OIKOS 2020. [DOI: 10.1111/oik.07156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Marco A. Molina‐Montenegro
- Inst. de Ciencias Biológicas, Univ. de Talca, Avda. Lircay s/n Talca Chile
- Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Universidad Católica del Norte Coquimbo Chile
- Centro de Investigación de Estudios Avanzados del Maule, Univ. Católica del Maule Talca Chile
| | - Mariela Baldelomar
- Inst. de Ciencias Biológicas, Univ. de Talca, Avda. Lircay s/n Talca Chile
| | - Cristian Atala
- Inst. de Biología, Facultad de Ciencias, Pontificia Univ. Católica de Valparaíso Valparaíso Chile
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Poudeyal MR, Meilby H, Shrestha BB, Ghimire SK. Harvest effects on density and biomass of Neopicrorhiza scrophulariiflora vary along environmental gradients in the Nepalese Himalayas. Ecol Evol 2019; 9:7726-7740. [PMID: 31346435 PMCID: PMC6635918 DOI: 10.1002/ece3.5355] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 12/25/2022] Open
Abstract
A surprisingly large number of species potentially threatened by human harvest lack quantitative ecological studies incorporating harvest effects, especially clonal species in the alpine Himalayas. We studied density and biomass variation of a threatened medicinal herb, Neopicrorhiza scrophulariiflora, to examine the effect of harvest on plant performance. The study covered two regions with contrasting harvest situations-one with open-access and another protected from commercial harvesting. Four populations from each region were compared along an elevation gradient (3,800-4,800 m). Also, we conducted in situ interviews with 165 and 38 medicinal and aromatic plant users in open-access and protected regions, respectively, to assess the collection and use patterns of the target species. The quantity harvested per household for traditional healthcare use was similar in both regions. We found no evidence of trade-driven collection in the protected region but in the open-access region a trade-based annual collection of 35-465 kg dried rhizomes per household had a strong negative effect on both density and biomass. In the protected region, the effect of harvest intensity on plant density was positive for vegetative and negative for reproductive individuals, whereas in the open-access region, the effect was negative for both vegetative and reproductive individuals. The results indicated that a low harvest intensity had no adverse impact on N. scrophulariiflora populations; however, quantification of the optimum level of harvest remains to be explored. Shrub vegetation appeared to buffer the harvest impact on plant density, possibly through the retention of additional moisture. To maintain population viability, we suggest regulating harvest, for example, by introducing rotational harvest systems, ensuring that a sufficient number of reproductive individuals are left as a source of propagules in each harvested population and that populations are given time to recover between harvests.
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Affiliation(s)
- Mukti Ram Poudeyal
- Central Department of BotanyTribhuvan UniversityKathmanduNepal
- Department of Food and Resource EconomicsUniversity of CopenhagenFrederiksberg CDenmark
| | - Henrik Meilby
- Department of Food and Resource EconomicsUniversity of CopenhagenFrederiksberg CDenmark
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Lucero JE, Noble T, Haas S, Westphal M, Butterfield H, Lortie CJ. The dark side of facilitation: native shrubs facilitate exotic annuals more strongly than native annuals. NEOBIOTA 2019. [DOI: 10.3897/neobiota.44.33771] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Positive interactions enhance biodiversity and ecosystem function, but can also exacerbate biological invasions. Facilitation of exotic invaders by exotic foundation species (invasional meltdown) has been studied extensively, but facilitation of exotic invaders by native foundation species has attracted less attention. Specifically, very few studies have examined the extent that native foundation species facilitate native and exotic competitors. Understanding the processes that mediate interactions between native and exotic species can help explain, predict, and improve management of biological invasions. Here, we examined the effects of native foundation shrubs on the relative abundance of the annual plant community – including native and exotic taxa – from 2015–2018 in a desert ecosystem at Carrizo Plain National Monument, California, USA (elevation: 723 m). Shrub effects varied by year and by the identity of annual species, but shrubs consistently enhanced the abundance of the annual plant community and facilitated both native (n=17 species) and exotic (n=4 species) taxa. However, at the provenance level, exotic annuals were facilitated 2.75 times stronger in abundance than native annuals, and exotic annuals were always more abundant than natives both near and away from shrubs. Our study reaffirms facilitation as an important process in the organisation of plant communities and confirms that both native and exotic species can form positive associations with native foundation species. However, facilitation by native foundation species can exacerbate biological invasions by increasing the local abundance of exotic invaders. Thus, the force of facilitation can have a dark side relevant to ecosystem function and management.
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15
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Zhou X, Zhang Y, An X, De Philippis R, Ma X, Ye C, Chen L. Identification of aqueous extracts from Artemisia ordosica and their allelopathic effects on desert soil algae. CHEMOECOLOGY 2019. [DOI: 10.1007/s00049-018-00276-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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16
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Lortie CJ, Gruber E, Filazzola A, Noble T, Westphal M. The Groot Effect: Plant facilitation and desert shrub regrowth following extensive damage. Ecol Evol 2018; 8:706-715. [PMID: 29321907 PMCID: PMC5756850 DOI: 10.1002/ece3.3671] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 10/13/2017] [Accepted: 11/03/2017] [Indexed: 11/12/2022] Open
Abstract
Deserts are increasing in extent globally, but existing deserts are decreasing in health. The basic biology and ecology of foundation plant species in deserts are limited. This is a direct study that provides an estimate of the capacity for a locally dominant foundation shrub species in California to recover from damage. Desert shrubs are cleared and damaged by humans for many purposes including agriculture, oil and gas production, and sustainable energy developments; we need to know whether foundation species consistently facilitate the abundance and diversity of other plants in high-stress ecosystems and whether they can recover. A total of 20 Ephedra californica shrubs were clipped to the ground at a single site and systematically resampled for regrowth 2 years later. These shrubs were damaged once and regrew rapidly, and relatively, larger shrubs were not more resilient. This study provides evidence for what we termed the "Groot Effect" because smaller individuals of this shrub species can recover from significant aboveground damage and continue to have positive effects on other plant species (similar to the popular culture reference to a benefactor tree species). The density of other plant species was consistently facilitated while effects on diversity varied with season. These findings confirm that E. californica is a foundation species that can be an important restoration tool within the deserts of California in spite of extreme cycles of drought and physical damage to its canopy.
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Affiliation(s)
| | - Eva Gruber
- Department of Wildlife Humboldt State University Arcata CA USA
| | | | - Taylor Noble
- Department of Biology York University Toronto ON Canada
| | - Michael Westphal
- Bureau of Land Management Central Coast Field Office Marina CA USA
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Wheeler HC, Høye TT, Svenning JC. Wildlife species benefitting from a greener Arctic are most sensitive to shrub cover at leading range edges. GLOBAL CHANGE BIOLOGY 2018; 24:212-223. [PMID: 28731522 DOI: 10.1111/gcb.13837] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 07/01/2017] [Indexed: 06/07/2023]
Abstract
Widespread expansion of shrubs is occurring across the Arctic. Shrub expansion will substantially alter arctic wildlife habitats. Identifying which wildlife species are most affected by shrubification is central to predicting future arctic community composition. Through meta-analysis, we synthesized the published evidence for effects of canopy-forming shrubs on birds and mammals in the Arctic and Subarctic. We examined variation in species behaviour, distribution and population dynamics in birds and mammals in response to shrub cover (including shrub cover indicators such as shrub occurrence, extent, density and height). We also assessed the degree of heterogeneity in wildlife responses to shrub cover and synthesized the remaining literature that did not fit the criteria for our quantitative meta-analyses. Species from higher green vegetation biomass habitats (high Normalized Difference Vegetation Index, NDVI, across their distribution) were more likely to respond positively to shrub cover, demonstrating the potential for species to expand from boreal to arctic habitats under shrubification. Wildlife populations located in the lowest vegetation biomass (low NDVI) areas of their species' range had the greatest proportion of positive responses to shrub cover, highlighting how increases in performance at leading edges of invaders distributions may be particularly rapid. This demonstrates the need to study species at these leading edges to accurately predict expansion potential. Arctic specialists were poorly represented across studies (limited to 5 bird and 0 mammal species), this knowledge gap potentially explains the few reported negative effects of shrub cover (3 of 29 species). Species responses to shrub cover showed substantial heterogeneity and varied among sites and years in all studies with sufficient replication to detect such variation. Our study highlights the importance of responses at species range edges in determining outcomes of shrubification for arctic birds and mammals and the need for greater examination of potential wildlife losers under shrubification.
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Affiliation(s)
- Helen C Wheeler
- Department of Bioscience, Section for Ecoinformatics and Biodiversity, Aarhus University, Aarhus C, Denmark
- Department of Arctic and Marine Biology, UiT the Arctic University of Norway, Tromsø, Norway
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS-Université de Montpellier-Université Paul-Valéry Montpellier-EPHE, Montpellier, France
- Centre for Northern Studies, Université du Québec à Rimouski, Rimouski, Canada
| | - Toke T Høye
- Arctic Research Centre, Aarhus University, Aarhus C, Denmark
- Department of Bioscience, Kalø, Aarhus University, Rønde, Denmark
| | - Jens-Christian Svenning
- Department of Bioscience, Section for Ecoinformatics and Biodiversity, Aarhus University, Aarhus C, Denmark
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Bråthen KA, Ravolainen VT, Stien A, Tveraa T, Ims RA. Rangifer management controls a climate-sensitive tundra state transition. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:2416-2427. [PMID: 28871616 DOI: 10.1002/eap.1618] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 06/26/2017] [Accepted: 07/28/2017] [Indexed: 05/12/2023]
Abstract
Rangifer (caribou/reindeer) management has been suggested to mitigate the temperature-driven transition of Arctic tundra into a shrubland state, yet how this happens is uncertain. Here we study this much focused ecosystem state transition in riparian areas, where palatable willows (Salix) are dominant tall shrubs and highly responsive to climate change. For the state transition to take place, small life stages must become tall and abundant. Therefore we predicted that the performance of small life stages (potential recruits) of the tall shrubs were instrumental to the focal transition, where Rangifer managed at high population density would keep the small-stage shrubs in a "browse trap" independent of summer temperature. We used a large-scale quasi-experimental study design that included real management units that spanned a wide range of Rangifer population densities and summer temperatures in order to assess the relative importance of these two driving variables. Ground surveys provided data on density and height of the small shrub life stages, while the distributional limit (shrubline) of established shrublands (the tall shrub life stage) was derived from aerial photographs. Where Rangifer densities were above a threshold of approximately 5 animals/km2 , we found, in accordance with the expectation of a "browse trap," that the small life stages of shrubs in grasslands were at low height and low abundance. At Rangifer densities below this threshold, the small life stages of shrubs were taller and more abundant indicating Rangifer were no longer in control of the grassland state. For the established shrubland state, we found that the shrubline was at a 100-m lower elevation in the management units where Rangifer had been browsing in summer as opposed to the migratory ranges with no browsing in summer. In both seasonal ranges, the shrubline increased 100 m per 1°C increment in temperature. Our study supports the proposal that Rangifer management within a sustainable range of animal densities can mitigate the much-focused transition from grassland to shrubland in a warming Arctic.
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Affiliation(s)
- Kari Anne Bråthen
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, N-9037, Tromsø, Norway
| | | | - Audun Stien
- The Norwegian Institute for Nature Research, Fram Centre, NO-9296, Tromsø, Norway
| | - Torkild Tveraa
- The Norwegian Institute for Nature Research, Fram Centre, NO-9296, Tromsø, Norway
| | - Rolf A Ims
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, N-9037, Tromsø, Norway
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Yu Q, Epstein H, Engstrom R, Walker D. Circumpolar arctic tundra biomass and productivity dynamics in response to projected climate change and herbivory. GLOBAL CHANGE BIOLOGY 2017; 23:3895-3907. [PMID: 28276177 DOI: 10.1111/gcb.13632] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
Satellite remote sensing data have indicated a general 'greening' trend in the arctic tundra biome. However, the observed changes based on remote sensing are the result of multiple environmental drivers, and the effects of individual controls such as warming, herbivory, and other disturbances on changes in vegetation biomass, community structure, and ecosystem function remain unclear. We apply ArcVeg, an arctic tundra vegetation dynamics model, to estimate potential changes in vegetation biomass and net primary production (NPP) at the plant community and functional type levels. ArcVeg is driven by soil nitrogen output from the Terrestrial Ecosystem Model, existing densities of Rangifer populations, and projected summer temperature changes by the NCAR CCSM4.0 general circulation model across the Arctic. We quantified the changes in aboveground biomass and NPP resulting from (i) observed herbivory only; (ii) projected climate change only; and (iii) coupled effects of projected climate change and herbivory. We evaluated model outputs of the absolute and relative differences in biomass and NPP by country, bioclimate subzone, and floristic province. Estimated potential biomass increases resulting from temperature increase only are approximately 5% greater than the biomass modeled due to coupled warming and herbivory. Such potential increases are greater in areas currently occupied by large or dense Rangifer herds such as the Nenets-occupied regions in Russia (27% greater vegetation increase without herbivores). In addition, herbivory modulates shifts in plant community structure caused by warming. Plant functional types such as shrubs and mosses were affected to a greater degree than other functional types by either warming or herbivory or coupled effects of the two.
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Affiliation(s)
- Qin Yu
- Department of Geography, The George Washington University, 1922F street NW, Washington, DC, 20052, USA
| | - Howard Epstein
- Department of Environmental Sciences, University of Virginia, 291 McCormick Rd, Charlottesville, VA, 22904, USA
| | - Ryan Engstrom
- Department of Geography, The George Washington University, 1922F street NW, Washington, DC, 20052, USA
| | - Donald Walker
- Arctic Geobotany Center, University of Alaska, Fairbanks, AK, USA
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Michalet R, Pugnaire FI. Facilitation in communities: underlying mechanisms, community and ecosystem implications. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12602] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Francisco I. Pugnaire
- Estación Experimental de Zonas Áridas Consejo Superior de Investigaciones Científicas Almería Spain
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21
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Mutual positive effects between shrubs in an arid ecosystem. Sci Rep 2015; 5:14710. [PMID: 26419958 PMCID: PMC4588512 DOI: 10.1038/srep14710] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 09/07/2015] [Indexed: 11/27/2022] Open
Abstract
One-way facilitation in plants has been found in many harsh environments and their role as structural forces governing species composition in plant communities is now well established. However, reciprocal positive effects benefiting two interacting species have seldom been reported and, in recent reviews, conceptually considered merely as facilitation when in fact there is room for adaptive strategies and evolutionary responses. We tested the existence of such reciprocal positive effects in an arid environment in SE Spain using spatial pattern analysis, a species removal experiment, and a natural experiment. We found that the spatial association between Maytenus senegalensis and Whitania frutescens, two shrub species of roughly similar size intimately interacting in our community, resulted in mutual benefit for both species. Benefits included improved water relations and nutritional status and protection against browsing, and did occur despite simultaneous competition for resources. Our data suggest two-way facilitation or, rather, a facultative mutualism among higher plant species, a process often overlooked which could be a main driver of plant community dynamics allowing for evolutionary processes.
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