Document Type : Research Paper
Rangeland ecosystems, covering approximately half of the Earth's terrestrial surface, represent a fundamental component of global ecological sustainability. These landscapes are critical not only for maintaining environmental balance but also for providing a wide array of ecosystem services. Key provisioning services include forage for livestock, medicinal plants, and resources for apiculture. Simultaneously, rangelands deliver essential regulating and supporting services, such as soil conservation, water cycle regulation, nutrient cycling, and erosion control. Moreover, they offer vital habitats for wildlife, significantly contributing to biodiversity preservation and overall ecological stability. Arid and semi-arid rangelands, characterized by inherent constraints such as limited precipitation, high temperatures, and shallow soils, are particularly sensitive to environmental fluctuations and anthropogenic pressures, making them inherently fragile ecosystems. Their susceptibility to climatic variability, combined with challenges such as overgrazing and vegetation degradation, underscores the urgent need for sustainable management and conservation strategies. Beyond their immediate ecological functions, preserving these ecosystems is essential for maintaining their capacity to provide multifunctional services, including soil quality enhancement, hydrological regulation, and nutrient retention, all of which are critical for long-term environmental health and human well-being. In Iran's Zagros Mountains, these ecosystems have suffered extensive degradation over decades due to chronic overgrazing and climatic pressures, resulting in substantial vegetation loss, accelerated soil erosion, and disruption of essential ecological processes. Pit-seeding is a widely employed, low-cost rehabilitation method designed to capture runoff, improve soil moisture, and facilitate plant establishment. However, significant knowledge gaps remain regarding its long-term efficacy in restoring comprehensive ecosystem health. Most existing studies have focused primarily on short-term vegetation responses, leaving the sustained impacts on soil biological properties particularly microbial communities that drive nutrient cycling and organic matter dynamics largely unquantified. This knowledge deficit is especially relevant in the highland rangelands of Tang-Sorkh, a representative and ecologically important area within the Zagros Mountains that supports local pastoral economies. Understanding the long-term trajectory of restoration in this region provides a valuable model for similar degraded landscapes. Accordingly, this study aimed to evaluate the 14-year effects of pit-seeding operations on a comprehensive set of indicators, including vegetation cover structure, key soil physicochemical properties, and fundamental soil biological health parameters in these degraded rangelands.
This study was conducted in the Tang-Sorkh highland rangelands, located in Kohgiluyeh and Boyer-Ahmad Province. The research was designed as a comparative study by selecting two adjacent areas with similar environmental conditions: one area subjected to Pit-Seeding operations with a 14-year history, and a control area with no history of rehabilitation practices. Vegetation sampling was carried out during the growing season using a randomized-systematic approach with transects and 1m×1m quadrats. Within each quadrat, the percent cover of vegetation, litter, bare soil, and gravel was recorded. Soil samples were collected from two depths (0-15 cm and 15-30 cm) using a completely random design from each study area. for physicochemical properties (texture, organic matter, phosphorus, potassium, CEC, etc.) and biological indices: Microbial Biomass Carbon (MBC) and Nitrogen (MBN) (by fumigation-extraction), Basal Respiration (BR), and Substrate-Induced Respiration (SIR) of the soil were measured in the laboratory. Statistical analysis of the data was performed using two-way analysis of variance (two-way ANOVA) in SPSS software version26.
The results indicated that pit-seeding induced significant changes in most of the studied variables. Vegetation cover (79.15%) and litter cover (16.44%) increased significantly, whereas bare soil (4.12%) and gravel cover (4.26%) decreased. Regarding soil physical properties, pit-seeding significantly increased clay content while reducing sand content and mean particle diameter (p < 0.01); however, no significant effect was observed on silt content (p > 0.05). In terms of soil chemical characteristics, pit-seeding had significant effects on soil pH, organic matter (OM), cation exchange capacity (CEC), phosphorus (P), potassium (K), and calcium (Ca) at the 1% probability level (p < 0.01), and on Ca(OH)₂ content at the 5% probability level (p < 0.05). In contrast, electrical conductivity (EC), sodium (Na), magnesium (Mg), chloride (Cl), and sodium adsorption ratio (SAR) were not significantly affected by the treatment (p > 0.05). Soil biological attributes exhibited the strongest response to pit-seeding, with basal respiration (BR), substrate-induced respiration (SIR), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and the microbial biomass C:N ratio being significantly influenced by the treatment (p < 0.01). The highest values of BR (1.949 mg CO₂ kg⁻1 soil h⁻1), SIR (2.136 mg CO₂ kg⁻1 soil h⁻1), MBC (260.00 mg kg-1), and MBN (13.85 mg kg-1) were recorded in the pit-seeded area within the 0–15 cm soil layer.
This study demonstrates that simple Pit-Seeding operations can effectively initiate a positive restoration feedback loop in degraded Mountain Rangelands, simultaneously improving vegetation, soil physicochemical quality, and most critically soil biological health. We highlight soil microbial parameters as essential indicators for monitoring rehabilitation success. For long-term resilience, Pit-Seeding should be integrated into participatory rangeland management programs, combined with native species seeding and managed grazing. Long-term monitoring of soil biological health is crucial to ensure sustained recovery. Our findings confirm Pit-Seeding as a practical, low-cost ecological tool for restoring ecosystem structure and function in semi-arid regions.
The study was funded by the University of Yasouj University, Yasouj, Iran.
The manuscript has a single author.
There is no use of any type of artificial intelligence-based technology in this paper.
Data available on request from the authors.
The author gratefully acknowledges Yasouj University, particularly the Faculty of Agriculture and Natural Resources, and the Agricultural and Natural Resources Research and Education Center of Kohgiluyeh and Boyer-Ahmad Province for their generous support and valuable assistance, which made this research possible.
The author declares no conflict of interest
