Volume 19, Issue 3 (9-2025)
مرتع 2025, 19(3): 316-332 |
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Saberi M, Dahmardeh Ghaleno M R, Khatibi R. Analysis of the effects of enclosure on soil biological indicators in Koteh rangelands of Khash County. مرتع 2025; 19 (3) :316-332
URL: http://rangelandsrm.ir/article-1-1323-en.html
URL: http://rangelandsrm.ir/article-1-1323-en.html
Department of Rangeland and Watershed Management Department, Faculty of Water and Soil, University of Zabol, Zabol
Abstract: (2026 Views)
Introduction and Objective: Soil microbial diversity plays a vital role in the functioning of rangeland ecosystems, particularly in biogeochemical cycles, organic matter decomposition, and the maintenance of soil fertility. Livestock grazing—one of the most widespread human activities in rangelands—can affect soil microbial communities by altering vegetation structure as well as soil physical and chemical properties. However, findings from previous studies on the effects of grazing on microbial diversity are often inconsistent, likely due to variations in climate, rangeland type, grazing intensity, and duration. A comprehensive analysis is therefore essential to better understand these impacts. Given the importance of evaluating how grazing exclusion (enclosure) influences soil biological characteristics—especially in arid and semi-arid regions that are highly sensitive to grazing—this study was conducted in the Koteh rangelands of Khash County, southeastern Iran.
Methodology: To examine the effects of grazing exclusion, 60 plots were established along six 100-meter transects using a random-systematic sampling design in both enclosed and grazed areas. Within each plot, vegetation cover, plant species, litter, stone and gravel cover, and bare soil percentage were recorded. Soil samples were collected from the beginning, middle, and end of each transect at two depths (0–15 cm and 15–30 cm). Three samples from each depth were combined into composite samples, yielding a total of 24 samples. These were analyzed for soil biological properties, including catalase enzyme activity, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal respiration, microbial population, and microbial contribution to soil. Statistical analyses were performed using SPSS software with paired and independent t-tests, while correlations among biological parameters were assessed using Pearson’s correlation coefficient in R.
Results: Vegetation cover in the enclosed area averaged 32.2%, compared to only 10.9% in the grazed area. All soil biological indicators were significantly higher in the surface layer (0–15 cm) than in the deeper layer (15–30 cm). For instance, catalase activity in the enclosed area averaged 55.77 μmol KMnO₄ g⁻¹ dry soil, significantly greater than 40.90 μmol KMnO₄ g⁻¹ dry soil in the grazed area. Microbial biomass nitrogen and microbial population in the enclosed site were 27.07 mg/kg and 3.96 mg/kg, respectively, both significantly higher at the 1% level. These findings clearly demonstrate that most microbial activity occurs in the topsoil due to higher levels of organic matter, oxygen, nitrogen, and metabolic processes. Strong positive correlations were observed between catalase activity and MBN (r = 0.91), and between catalase activity and microbial population (r = 0.92), indicating that increased microbial activity enhances catalase levels, which serve as indicators of soil biological health. MBN also showed strong correlations with microbial contribution (r = 0.84) and microbial population (r = 0.87), underscoring its central role in nutrient cycling.
Conclusion: Catalase activity, microbial biomass nitrogen, microbial population, and microbial contribution can serve as reliable bioindicators for assessing soil health in rangeland ecosystems. Overall, all measured biological properties were significantly improved in the enclosed area compared to the grazed area at both soil depths. These results demonstrate that intensive grazing reduces microbial activity, diminishes soil fertility, and disrupts biogeochemical processes. Consequently, implementing enclosure strategies or rotational grazing management is strongly recommended to restore the biological and physicochemical functions of soils in rangeland ecosystems.
Methodology: To examine the effects of grazing exclusion, 60 plots were established along six 100-meter transects using a random-systematic sampling design in both enclosed and grazed areas. Within each plot, vegetation cover, plant species, litter, stone and gravel cover, and bare soil percentage were recorded. Soil samples were collected from the beginning, middle, and end of each transect at two depths (0–15 cm and 15–30 cm). Three samples from each depth were combined into composite samples, yielding a total of 24 samples. These were analyzed for soil biological properties, including catalase enzyme activity, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal respiration, microbial population, and microbial contribution to soil. Statistical analyses were performed using SPSS software with paired and independent t-tests, while correlations among biological parameters were assessed using Pearson’s correlation coefficient in R.
Results: Vegetation cover in the enclosed area averaged 32.2%, compared to only 10.9% in the grazed area. All soil biological indicators were significantly higher in the surface layer (0–15 cm) than in the deeper layer (15–30 cm). For instance, catalase activity in the enclosed area averaged 55.77 μmol KMnO₄ g⁻¹ dry soil, significantly greater than 40.90 μmol KMnO₄ g⁻¹ dry soil in the grazed area. Microbial biomass nitrogen and microbial population in the enclosed site were 27.07 mg/kg and 3.96 mg/kg, respectively, both significantly higher at the 1% level. These findings clearly demonstrate that most microbial activity occurs in the topsoil due to higher levels of organic matter, oxygen, nitrogen, and metabolic processes. Strong positive correlations were observed between catalase activity and MBN (r = 0.91), and between catalase activity and microbial population (r = 0.92), indicating that increased microbial activity enhances catalase levels, which serve as indicators of soil biological health. MBN also showed strong correlations with microbial contribution (r = 0.84) and microbial population (r = 0.87), underscoring its central role in nutrient cycling.
Conclusion: Catalase activity, microbial biomass nitrogen, microbial population, and microbial contribution can serve as reliable bioindicators for assessing soil health in rangeland ecosystems. Overall, all measured biological properties were significantly improved in the enclosed area compared to the grazed area at both soil depths. These results demonstrate that intensive grazing reduces microbial activity, diminishes soil fertility, and disrupts biogeochemical processes. Consequently, implementing enclosure strategies or rotational grazing management is strongly recommended to restore the biological and physicochemical functions of soils in rangeland ecosystems.
Type of Study: Research |
Subject:
Special
Received: 2025/05/7 | Accepted: 2025/07/14 | Published: 2025/09/1
Received: 2025/05/7 | Accepted: 2025/07/14 | Published: 2025/09/1
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