Abstract: (56 Views)
Background and Objective: Understanding the interrelationships between plants and their impact on the survival of rangeland species plays a vital role in sustainable management and conservation of biodiversity in rangeland ecosystems. This study aimed to investigate the role of nurse species in maintaining species diversity under the influence of different grazing levels and climatic conditions. The present study was conducted in four climatic regions (Sangsefid: semi-desert, Moote: steppe, Tangsayad: semi-steppe, Sabzkooh: humid semi-steppe) of Isfahan and Chaharmahal and Bakhtiari provinces to evaluate the impact of livestock grazing and climate on the performance of nurse plants.
Materials and Methods: In each climatic region, seven sites with heavy and light grazing levels were selected. In each site, three 30
macroplots and four 2
Results: The results showed that nurse plants increase species richness through a facilitating effect. However, the response of this system to high grazing stress was climate-dependent: in semi-desert (Sangsefid) and humid semi-steppe (Sabzkooh) climates, high grazing intensity reduced the facilitating effect, while in steppe (Moote) and semi-steppe (Tangsayad) climates, this effect was enhanced. It was also observed that in drier climates (semi-desert and steppe), nurse plants reduced diversity and evenness by creating competition, but this competitive effect was reduced under high grazing stress. In contrast, in wetter climates (semi-steppe and humid semi-steppe), nurse plants increased species diversity and evenness of the ecosystem by enhancing their facilitating effect under high grazing conditions.
Conclusion: Rangeland management should be designed based on the specific climatic conditions of each region and livestock grazing patterns. This study shows that the effect of nurse species and other management measures is strongly influenced by these two factors. Therefore, planning should be flexible and based on a careful assessment of local conditions in order to maintain and improve rangeland biodiversity.
Materials and Methods: In each climatic region, seven sites with heavy and light grazing levels were selected. In each site, three 30
macroplots and four 2 microplots (three plots with nurse species and one control plot) were established. Species diversity indices including Shannon diversity, Simpson diversity, species richness, Shannon evenness and Simpson evenness were calculated. Repeated Measure test was used to examine differences in climates, grazing intensity and their combined effects on the indices, and Principal Component Analysis (PCA) was used to examine changes in species diversity and identify patterns of change between two paired plots. Then, the biological relationship index was calculated for the indices.Results: The results showed that nurse plants increase species richness through a facilitating effect. However, the response of this system to high grazing stress was climate-dependent: in semi-desert (Sangsefid) and humid semi-steppe (Sabzkooh) climates, high grazing intensity reduced the facilitating effect, while in steppe (Moote) and semi-steppe (Tangsayad) climates, this effect was enhanced. It was also observed that in drier climates (semi-desert and steppe), nurse plants reduced diversity and evenness by creating competition, but this competitive effect was reduced under high grazing stress. In contrast, in wetter climates (semi-steppe and humid semi-steppe), nurse plants increased species diversity and evenness of the ecosystem by enhancing their facilitating effect under high grazing conditions.
Conclusion: Rangeland management should be designed based on the specific climatic conditions of each region and livestock grazing patterns. This study shows that the effect of nurse species and other management measures is strongly influenced by these two factors. Therefore, planning should be flexible and based on a careful assessment of local conditions in order to maintain and improve rangeland biodiversity.
Keywords: Facilitation, Species Diversity, Livestock Grazing, Biological Relationships, Nurse Species
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