Volume 19, Issue 4 (12-2025)
مرتع 2025, 19(4): 469-483 |
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Saberi M, Behi M, Karimian V. Assessing the Impact of Grazing Exclosure on Soil Organic Carbon and Nitrogen Storage and Vegetation Characteristics in Dryland Rangelands: A Case Study of Dasht Sarbisheh, South Khorasan Province. مرتع 2025; 19 (4) :469-483
URL: http://rangelandsrm.ir/article-1-1337-en.html
URL: http://rangelandsrm.ir/article-1-1337-en.html
Department of Rangeland and Watershed Management, Faculty of Water and Soil, University of Zabol, Zabol
Abstract: (1993 Views)
Background and Objectives: Rangeland ecosystems cover roughly half of the Earth's land surface and play a critical role in ecological stability, biomass production, and nutrient cycling. Soil organic carbon and nitrogen storage are key indicators of rangeland health, particularly in arid and semi-arid regions, where ecosystems are highly sensitive to environmental stress and soil degradation. Effective rangeland management, such as enclosure, can enhance soil conditions and increase carbon and nitrogen storage by influencing biological and chemical soil processes. This study aimed to evaluate the effects of enclosure on total soil organic carbon and nitrogen stocks, plant species diversity, and vegetation cover in the arid and semi-arid rangelands of the Sarbisheh Plain, South Khorasan Province.
Methodology: Two sites with similar physiographic, climatic, and topographic conditions were selected- one under enclosure management and the other subject to free grazing. Soil sampling was conducted in May 2021 using a systematic random method. Six 100-meter transects were established per site, with ten 2×2-meter plots along each transect. Soil samples were collected at three depths (0–15, 15–30, and 30–45 cm) after removing litter, and composite samples were prepared for laboratory analysis of organic carbon and total nitrogen. Vegetation parameters were also recorded. Data were analyzed using a completely randomized design with one-way ANOVA and independent t-tests to assess differences between treatments.
Results: Vegetation diversity and canopy cover were significantly higher in the enclosed area compared to the grazed area (23.5% vs. 11.2%). Dominant species in both sites were perennial shrubs from the Papilionaceae, Compositae, and Chenopodiaceae families. Soil depth significantly influenced all measured parameters (p < 0.01). Organic carbon (2.12 g/kg) and total nitrogen (0.8 g/kg) were highest in the surface layer (0–15 cm), while bulk density increased with depth, reaching 1.29 g/cm³ at 30–45 cm. Despite lower nutrient concentrations at depth, the highest carbon stock (7.79 t/ha) occurred in the 30–45 cm layer due to higher soil density. The enclosed site had significantly higher carbon stocks than the grazed site (6.53 vs. 3.07 t/ha), and nitrogen stocks were significantly greater at the intermediate depth (15–30 cm).
Conclusion: Enclosure effectively enhances biodiversity and improves soil quality by reducing grazing pressure. By increasing soil carbon and nitrogen storage, enclosures contribute to ecosystem function and climate change mitigation in arid and semi-arid rangelands. Periodic enclosure practices, combined with complementary restoration techniques such as native species cultivation and soil physical improvement, are recommended to enhance ecological resilience and ensure the sustainable use of rangeland ecosystems.
Methodology: Two sites with similar physiographic, climatic, and topographic conditions were selected- one under enclosure management and the other subject to free grazing. Soil sampling was conducted in May 2021 using a systematic random method. Six 100-meter transects were established per site, with ten 2×2-meter plots along each transect. Soil samples were collected at three depths (0–15, 15–30, and 30–45 cm) after removing litter, and composite samples were prepared for laboratory analysis of organic carbon and total nitrogen. Vegetation parameters were also recorded. Data were analyzed using a completely randomized design with one-way ANOVA and independent t-tests to assess differences between treatments.
Results: Vegetation diversity and canopy cover were significantly higher in the enclosed area compared to the grazed area (23.5% vs. 11.2%). Dominant species in both sites were perennial shrubs from the Papilionaceae, Compositae, and Chenopodiaceae families. Soil depth significantly influenced all measured parameters (p < 0.01). Organic carbon (2.12 g/kg) and total nitrogen (0.8 g/kg) were highest in the surface layer (0–15 cm), while bulk density increased with depth, reaching 1.29 g/cm³ at 30–45 cm. Despite lower nutrient concentrations at depth, the highest carbon stock (7.79 t/ha) occurred in the 30–45 cm layer due to higher soil density. The enclosed site had significantly higher carbon stocks than the grazed site (6.53 vs. 3.07 t/ha), and nitrogen stocks were significantly greater at the intermediate depth (15–30 cm).
Conclusion: Enclosure effectively enhances biodiversity and improves soil quality by reducing grazing pressure. By increasing soil carbon and nitrogen storage, enclosures contribute to ecosystem function and climate change mitigation in arid and semi-arid rangelands. Periodic enclosure practices, combined with complementary restoration techniques such as native species cultivation and soil physical improvement, are recommended to enhance ecological resilience and ensure the sustainable use of rangeland ecosystems.
Keywords: Enclosure management, Rangeland ecosystems, Carbon sequestration, Soil quality, Soil organic carbon
Type of Study: Research |
Subject:
Special
Received: 2025/07/27 | Accepted: 2025/08/26 | Published: 2025/12/1
Received: 2025/07/27 | Accepted: 2025/08/26 | Published: 2025/12/1
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