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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)
URL: http://rangelandsrm.ir/article-1-1335-en.html
URL: http://rangelandsrm.ir/article-1-1335-en.html
Fasa University
Abstract: (21 Views)
Background and objectives: Proper and sustainable management of rangeland ecosystems depends on preserving the highest possible number of native species within these ecosystems. One of the main methods for evaluating and understanding rangelands is determining their species diversity. Accordingly, the present study was conducted to examine the management effects of implementing protected closures on the floristic composition, biodiversity, and stability of dominant species in the Mianjangal region of Fasa, Fars Province. This area is characterized by a rich flora, with key plant elements including various species of almonds, Astragalus (Gon), and grasses.
Methodology: The Mianjangal rangelands, with an area of 2,300 hectares, are located 90 kilometers from the Shiraz–Fasa road, in the northwest of Fasa County, at a geographical position between 29°07′ to 29°11′ N latitude and 53°20′ to 53°25′ E longitude. Field sampling was conducted under two management conditions: enclosure and non-enclosure, and the resulting data were analyzed. To investigate the effect of management conditions on biodiversity, various indices such as the Shannon index, species richness, and species evenness were calculated and compared. To compare the similarity between the two conditions (enclosure and grazing), distance-based indices such as the Jaccard index and the Sorensen index were used. To examine species aggregation patterns and evaluate differences between the two conditions, NMDS (Non-metric Multidimensional Scaling) was applied. To assess the effect of enclosure and grazing conditions on plant biodiversity, three major diversity indices—Shannon index, species richness, and evenness—were calculated and compared using statistical tests. The normality test for the Shannon index showed that the data were normally distributed; therefore, the independent t-test (Welch Two Sample t-test) was used to compare the means. Species with an average cover greater than 1% in each treatment were identified as dominant species. Then, by comparing the frequency and mean cover of these species across plots within each treatment, the more stable dominant species were determined.
Results: The results showed that the Shannon index in fenced areas was significantly higher than in grazing areas (p < 0.001; df = 44.8; t = 8.78), indicating greater species diversity in these areas. Additionally, species similarity indices such as Jaccard and Sorensen showed higher homogeneity in the plant composition of fenced areas compared to non-fenced areas, indicating a more diverse and stable structure of plant communities under fenced management. The average Sorensen similarity index for plant species was 0.19 in fenced areas and 0.17 in grazing areas. The results of NMDS analysis and the permutation-based analysis of variance (PERMANOVA) confirmed a significant difference in plant community structure between the two management conditions. In fenced areas, 28 unique species were identified, while in non-fenced areas only one unique species was observed, highlighting the important role of enclosures in maintaining and enhancing species diversity. These species include representatives from various genera such as Achillea wilhelmsii, Ajuga chamaecistus, Amygdalus scoparia, and Daphne mucronata. Furthermore, dominant species in the fenced areas, in addition to exhibiting greater diversity, were more stable, and biological forms such as geophytes, hemicryptophytes, and phanerophytes also had higher densities in these areas.
Methodology: The Mianjangal rangelands, with an area of 2,300 hectares, are located 90 kilometers from the Shiraz–Fasa road, in the northwest of Fasa County, at a geographical position between 29°07′ to 29°11′ N latitude and 53°20′ to 53°25′ E longitude. Field sampling was conducted under two management conditions: enclosure and non-enclosure, and the resulting data were analyzed. To investigate the effect of management conditions on biodiversity, various indices such as the Shannon index, species richness, and species evenness were calculated and compared. To compare the similarity between the two conditions (enclosure and grazing), distance-based indices such as the Jaccard index and the Sorensen index were used. To examine species aggregation patterns and evaluate differences between the two conditions, NMDS (Non-metric Multidimensional Scaling) was applied. To assess the effect of enclosure and grazing conditions on plant biodiversity, three major diversity indices—Shannon index, species richness, and evenness—were calculated and compared using statistical tests. The normality test for the Shannon index showed that the data were normally distributed; therefore, the independent t-test (Welch Two Sample t-test) was used to compare the means. Species with an average cover greater than 1% in each treatment were identified as dominant species. Then, by comparing the frequency and mean cover of these species across plots within each treatment, the more stable dominant species were determined.
Results: The results showed that the Shannon index in fenced areas was significantly higher than in grazing areas (p < 0.001; df = 44.8; t = 8.78), indicating greater species diversity in these areas. Additionally, species similarity indices such as Jaccard and Sorensen showed higher homogeneity in the plant composition of fenced areas compared to non-fenced areas, indicating a more diverse and stable structure of plant communities under fenced management. The average Sorensen similarity index for plant species was 0.19 in fenced areas and 0.17 in grazing areas. The results of NMDS analysis and the permutation-based analysis of variance (PERMANOVA) confirmed a significant difference in plant community structure between the two management conditions. In fenced areas, 28 unique species were identified, while in non-fenced areas only one unique species was observed, highlighting the important role of enclosures in maintaining and enhancing species diversity. These species include representatives from various genera such as Achillea wilhelmsii, Ajuga chamaecistus, Amygdalus scoparia, and Daphne mucronata. Furthermore, dominant species in the fenced areas, in addition to exhibiting greater diversity, were more stable, and biological forms such as geophytes, hemicryptophytes, and phanerophytes also had higher densities in these areas.
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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