Volume 19, Issue 3 (9-2025)
مرتع 2025, 19(3): 333-353 |
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Mirshekari1 Z, Asadi Borujeni E, Tahmasebi Kahyani P. The role of nurse species in moderating the effects of climate and livestock grazing in semi-desert, steppe, and semi-steppe regions. مرتع 2025; 19 (3) :333-353
URL: http://rangelandsrm.ir/article-1-1327-en.html
URL: http://rangelandsrm.ir/article-1-1327-en.html
Department of Rangeland and Watershed, Faculty of Natural Resources and Earth Sciences, Shahrekord University, Shahrekord
Abstract: (1878 Views)
Introduction and Objective: Understanding the interactions among plants and their influence on the survival of rangeland species is critical for sustainable management and biodiversity conservation in rangeland ecosystems. This study investigated the role of nurse species in sustaining species diversity under varying grazing intensities and climatic conditions. Research was conducted across four climatic regions -Sangsefid (semi-desert), Mouteh (steppe), and Tangsayad and Sabzkouh (semi-steppe)- in the provinces of Isfahan and Chaharmahal and Bakhtiari, to assess the combined effects of livestock grazing and climate on the performance of nurse plants.
Methodology: Within each climatic region, seven sites representing heavy and light grazing intensities were selected. At each site, three 30 m² macroplots were established, each containing four 2 m² microplots: three with nurse species and one control plot in comparable areas lacking nurse species. Nurse species were chosen based on at least one of the following criteria: (1) creating favorable microclimates, (2) possessing effective physical structures, or (3) adapting to harsh environmental conditions. Species diversity indices -including Shannon diversity, Simpson diversity, species richness, Shannon evenness, and Simpson evenness- were calculated. A Repeated Measures test was applied to evaluate differences across climates, grazing intensities, and their interactions. Principal Component Analysis (PCA) was used to assess changes in species diversity and to identify patterns between paired plots. Subsequently, a biological relationship index was calculated for the diversity metrics.
Results: Nurse plants consistently enhanced species richness across all climatic regions through their facilitative effects. However, system responses to high grazing pressure varied by climate: in semi-desert (Sangsefid) and semi-steppe (Sabzkouh) regions, heavy grazing reduced facilitation, whereas in steppe (Mouteh) and semi-steppe (Tangsayad) regions, facilitation was strengthened. In drier climates (semi-desert and steppe), nurse plants decreased diversity and evenness due to competitive interactions, though this competitive effect diminished under high grazing stress. Conversely, in wetter climates (semi-steppe), nurse plants increased species diversity and evenness by amplifying their facilitative role under heavy grazing conditions.
Conclusion: Effective rangeland management must account for the specific climatic context and grazing patterns of each region. The findings demonstrate that the influence of nurse species -and the success of other management interventions-is strongly shaped by these two factors. Consequently, management strategies should remain flexible and grounded in careful local assessments to sustain and enhance rangeland biodiversity.
Methodology: Within each climatic region, seven sites representing heavy and light grazing intensities were selected. At each site, three 30 m² macroplots were established, each containing four 2 m² microplots: three with nurse species and one control plot in comparable areas lacking nurse species. Nurse species were chosen based on at least one of the following criteria: (1) creating favorable microclimates, (2) possessing effective physical structures, or (3) adapting to harsh environmental conditions. Species diversity indices -including Shannon diversity, Simpson diversity, species richness, Shannon evenness, and Simpson evenness- were calculated. A Repeated Measures test was applied to evaluate differences across climates, grazing intensities, and their interactions. Principal Component Analysis (PCA) was used to assess changes in species diversity and to identify patterns between paired plots. Subsequently, a biological relationship index was calculated for the diversity metrics.
Results: Nurse plants consistently enhanced species richness across all climatic regions through their facilitative effects. However, system responses to high grazing pressure varied by climate: in semi-desert (Sangsefid) and semi-steppe (Sabzkouh) regions, heavy grazing reduced facilitation, whereas in steppe (Mouteh) and semi-steppe (Tangsayad) regions, facilitation was strengthened. In drier climates (semi-desert and steppe), nurse plants decreased diversity and evenness due to competitive interactions, though this competitive effect diminished under high grazing stress. Conversely, in wetter climates (semi-steppe), nurse plants increased species diversity and evenness by amplifying their facilitative role under heavy grazing conditions.
Conclusion: Effective rangeland management must account for the specific climatic context and grazing patterns of each region. The findings demonstrate that the influence of nurse species -and the success of other management interventions-is strongly shaped by these two factors. Consequently, management strategies should remain flexible and grounded in careful local assessments to sustain and enhance rangeland biodiversity.
Keywords: Facilitation, Species Diversity, Livestock Grazing, Biological Relationships, Nurse Species
Type of Study: Research |
Subject:
Special
Received: 2025/05/14 | Accepted: 2025/07/22 | Published: 2025/09/1
Received: 2025/05/14 | Accepted: 2025/07/22 | Published: 2025/09/1
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