Evaluating the Effect of Tropical Range Management on the Development of Soil Properties and Carbon Stores (Case study: South of Ghasreshirin in Kermanshah Province)

Rangelands not only contribute to forage production, but also play an important role in terms of sustaining environment and habitats, by production (medicine plants), biodiversity, soil and water conservation, curtailing greenhouse gasses as well as enhancement of truisms industry. However, rangelands, particularly winter-side ranges are suffering from improper utility, converting to other land uses (mainly rain-fed lands) and fire burning. The preset study, which was conducted in the Ghasreshirin (Kermanshah, Iran), aims to to evaluate the effects of rehabilitation measures on vegetation and soil. The measures were selected as the experimental treatments including Furrowing-Pitting-Preservation (FPP), Pitting, Brush- planting- Preservation (PBP), Grazing Management (GM) and Current Utility (CU). The characteristic of vegetation including biomass production, capacity, trend, condition were assessed using both transect and quadrate performance. Soil sampling also carried out from soil surface (0-10 cm) and subjected to soil analysis mainly texture, pH, electrical conductivity (EC), calcite (TNV) and soil organic carbon (SOC). The statistical analysis revealed that there were significant differences for some variables among treatments. Thus, forage production in PBP was significant higher level (551 kgha-1) compared to CU treatment (196 kgha-1). Furthermore, the respective values of SOC in the first, second, third and fourth treatments were 0.82, 0.90, 0.86 and 0.38 percent, indicating the effect of measures on SOC enhancement in the study area, while there was higher in PBP treatment. By and large, we can prioritize the effective treatments for sustaining rangeland FPP, PBP and GM, respectively. These rangelands are being degraded through over utility of these rangelands and converting them to other land uses. Moreover, these rangelands are located at the geological marls formation (Aghajari Formation) inducing a soil with high level of silt content and subsequently susceptible to wind erosion where subjected to overgrazing and converting to other land uses. This situation may attributes to severe water and wind erosion as well as desertification making sources for dust blowing and other environmental impacts.
Extended Abstract
1- Rangelands cover most parts of lands worldwide. In Iran, rangeland includes 54% of country area in which 1.2 million ha is located in Kermanshah Province. However, rangelands are suffering from improper management and utilization activities, impacting environmental hazards and unsustainable activities at the local, regional and global scale. Considering relevant literature review and research results, both soil and vegetation of rangelands are negatively affected by improper grazing (early and heavy grazing) and management that can be curtailed through rangeland rehabilitation measures mainly grazing management, seed sowing, furrowing, pitting and runoff harvesting. ), the objective of this research which was conducted in the Ghasreshirin Kermanshah, Iran, was to evaluate the effects of rehabilitation measures on vegetation and soil characteristics.
2- The study site (Chegha-hamam) is located in Ghasreshirin, west Kermanshah province, Iran representing the winter rangelands within province. The mean annual rainfall is about 300 mm, thus Salsola regedula and annual species are dominant vegetation. The rehabilitations practices were measured based on range management projects that was planned and lunched by Natural Resources Office of Kermanshah province during 2010-12. In this study, each measure supposed as an experimental measure comprise furrowing + shrub planting (FSP), pitting + shrub planting (PSP), grazing system management (GSM) and current improper grazing or control treatment (CT). The planted shrub was Atriplex sp. Total 32 soil samples were taken from surface layer (0-10 cm) and air-derided for soil analysis including soil organic carbon (Walky and Black method), particle size distribution (hydrometric method), carbonate (titration method), pH (saturated paste) and bulk density (natural core sample). The characteristic of vegetation including biomass production, capacity, trend, condition were assessed using both transect and quadrate performance.
3- Results explored that FSP, PSP and GSM contributed considerable improvement in vegetation cover compared with CT. Thus increasing in plant cover was found about 60% for Salsola regedula and Atriplex sp.in these treatments, while there was 395 in CT.Furthermore, plant litter also enhanced and soil bare was reduced as the consequent of plant cover. However, the hit of heavy and early grazing in CT caused negative rangeland trend and subsequently reduction in plant cover pattern mainly frequent of annual vegetation and accelerating soil erosion and compaction. The statistical analysis revealed that there was a significant difference for some SOC level among treatments. The higher level of SOC was found in PSP (0.90%) compared with CT (0.38%). In contrast there were no significant changes through treatments for electrical conductivity, pH, sand, silt and clay variables. In other hand, the furrowing and pitting did not affect these soil characteristics, while the change in plant cover, SOC and its sequestration was significant through treatments. The sequestered SOC in FSP, PSP, GSM and CT was 1043.91, 1145.60, 874.71 and 509.20 kg ha-1, respectively indicating higher level (p<0.05) in FSP compared to CT. Thus, biomechanical measure (furrowing and pitting) cause reduction in SOC emotion.
4- Considering these results, proper grazing and biomechanical measures attribute to significant increase in vegetation cover, plant litter and adversely reduction in bare soil. Although some chemical and physical soil characteristics were not affected by treatments, the SOC was improved followed by vegetation cover leading to the enhancement of SOC from 0.28% to 0.90%. Based on relevant literature reviews, most similar researches confirm the effects of proper management and soil conservation measures, particularly grazing management, furrowing, pitting and rainwater catchment on SOC stock and carbon sequestration.
By and large, we can prioritize the effective treatments for sustaining rangeland FPP, PBP and GM, respectively. These rangelands are being degraded through over utility of these rangelands and converting them to other land uses. Moreover, these rangelands are located at the geological marl formation (Aghajari Formation) inducing a soil with high level of silt content and subsequently susceptible to wind erosion where subjected to overgrazing and converting to other land uses. This situation may attribute to severe water and wind erosion as well as desertification making sources for dust blowing and other environmental impacts.