Volume 19, Issue 3 (9-2025)
مرتع 2025, 19(3): 354-371 |
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Jahantab E, Sharafatmandrad M, Badehian Z. Comparative Analysis of Floristic Composition and Dominant Species Stability in Enclosed and Grazed Rangelands; Case Study: Mianjangal Region, Fasa. مرتع 2025; 19 (3) :354-371
URL: http://rangelandsrm.ir/article-1-1335-en.html
URL: http://rangelandsrm.ir/article-1-1335-en.html
Department of range and Watershed Management, Faculty of Agriculture, Fasa University, Fasa
Abstract: (493 Views)
Introduction and Objective: Sustainable management of rangeland ecosystems relies on preserving the maximum possible number of native species. Species diversity is one of the primary measures for evaluating and understanding rangeland health. Accordingly, this study examined the effects of protected enclosures on floristic composition, plant diversity, and the stability of dominant species in the Mianjangal region of Fasa, Fars Province. This area is notable for its rich flora, including various Almond species, Astragalus (Gon), and Grasses.
Methodology: The Mianjangal rangelands, covering 2,300 hectares, are located 90 km from the Shiraz–Fasa road in northwest Fasa County, between 29°07′–29°11′ N latitude and 53°20′–53°25′ E longitude. Field sampling was conducted under two management regimes: enclosure and non-enclosure. To assess biodiversity, indices such as Shannon diversity, species richness, and species evenness were calculated and compared. Similarity between the two conditions (enclosure vs. grazing) was evaluated using distance-based indices including Jaccard and Sorensen. Species aggregation patterns and differences between conditions were analyzed using Non-metric Multidimensional Scaling (NMDS). To test the effects of enclosure and grazing on biodiversity, three major indices -Shannon diversity, richness, and evenness -were statistically compared. Normality testing confirmed that Shannon index data were normally distributed; therefore, Welch’s two-sample t-test was applied. Species with average cover greater than 1% in each treatment were identified as dominant, and their stability was determined by comparing frequency and mean cover across plots.
Results: The Shannon index was significantly higher in fenced areas compared to grazed areas (p < 0.001; df = 44.8; t = 8.78), indicating greater species diversity under enclosure management. Similarity indices (Jaccard and Sorensen) revealed higher homogeneity in fenced plots, reflecting a more diverse and stable plant community structure. The average Sorensen similarity index was 0.19 in fenced areas versus 0.17 in grazed areas. NMDS and PERMANOVA analyses confirmed significant differences in community composition between the two management regimes. In fenced areas, 28 unique species were recorded, compared to only one in grazed areas, underscoring the role of enclosures in maintaining and enhancing diversity. These species included Achillea wilhelmsii, Ajuga chamaecistus, Amygdalus scoparia, and Daphne mucronata. Dominant species in fenced areas were not only more diverse but also more stable, with higher densities of biological forms such as geophytes, hemicryptophytes, and phanerophytes.
Conclusion: Enclosure management significantly improves ecological structure, enhances the stability and sustainability of plant communities, and promotes biodiversity in rangelands. Based on these findings, enclosure can be considered an effective strategy in sustainable natural resource management, helping to maintain ecological balance, optimize utilization, and ensure long-term conservation. Overall, the results demonstrate that protecting rangelands through enclosure (with 29 years of implementation) leads to higher biodiversity and a more stable plant community structure compared to grazing.
Methodology: The Mianjangal rangelands, covering 2,300 hectares, are located 90 km from the Shiraz–Fasa road in northwest Fasa County, between 29°07′–29°11′ N latitude and 53°20′–53°25′ E longitude. Field sampling was conducted under two management regimes: enclosure and non-enclosure. To assess biodiversity, indices such as Shannon diversity, species richness, and species evenness were calculated and compared. Similarity between the two conditions (enclosure vs. grazing) was evaluated using distance-based indices including Jaccard and Sorensen. Species aggregation patterns and differences between conditions were analyzed using Non-metric Multidimensional Scaling (NMDS). To test the effects of enclosure and grazing on biodiversity, three major indices -Shannon diversity, richness, and evenness -were statistically compared. Normality testing confirmed that Shannon index data were normally distributed; therefore, Welch’s two-sample t-test was applied. Species with average cover greater than 1% in each treatment were identified as dominant, and their stability was determined by comparing frequency and mean cover across plots.
Results: The Shannon index was significantly higher in fenced areas compared to grazed areas (p < 0.001; df = 44.8; t = 8.78), indicating greater species diversity under enclosure management. Similarity indices (Jaccard and Sorensen) revealed higher homogeneity in fenced plots, reflecting a more diverse and stable plant community structure. The average Sorensen similarity index was 0.19 in fenced areas versus 0.17 in grazed areas. NMDS and PERMANOVA analyses confirmed significant differences in community composition between the two management regimes. In fenced areas, 28 unique species were recorded, compared to only one in grazed areas, underscoring the role of enclosures in maintaining and enhancing diversity. These species included Achillea wilhelmsii, Ajuga chamaecistus, Amygdalus scoparia, and Daphne mucronata. Dominant species in fenced areas were not only more diverse but also more stable, with higher densities of biological forms such as geophytes, hemicryptophytes, and phanerophytes.
Conclusion: Enclosure management significantly improves ecological structure, enhances the stability and sustainability of plant communities, and promotes biodiversity in rangelands. Based on these findings, enclosure can be considered an effective strategy in sustainable natural resource management, helping to maintain ecological balance, optimize utilization, and ensure long-term conservation. Overall, the results demonstrate that protecting rangelands through enclosure (with 29 years of implementation) leads to higher biodiversity and a more stable plant community structure compared to grazing.
Keywords: Functional diversity, Ecological indicators, Plant community structure, Life forms, Grazing management, NMDS analysis, Shannon index
Type of Study: Research |
Subject:
Special
Received: 2025/07/4 | Accepted: 2025/09/11 | Published: 2025/09/1
Received: 2025/07/4 | Accepted: 2025/09/11 | Published: 2025/09/1
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