چكيده لاتين :
Introduction
Rangelands are natural ecosystems whit native plant species cover and are suitable for grazing. Water, soil and vegetation have fundamental role in maintaining natural ecosystems such as rangelands, so, performing the researches that lead to the preservation of natural environment and human’s environment is essential. Proper and allowable utilization of rangelands in the range management projects is the important scientific and technical measure in the range management of Iran. Range management projects as improvement - restoration and reclamation guideline have particular importance in the natural resources’ organization. On the other hand, today, erosion and soil loss and sediment production has become one of the main problems in the human environment. Restoration of vegetation and its effects on reduce of erosion have been studied by Li, 2006, Zhou, et al. 2008, Zhanga et al. 2004, Abdelkrima, et al. 2013. Goal of improvement - restoration operations in natural ecosystems is recovery plant compositon and cover for more protection of water and soil and decrease of erosion soil, finally increase forage yield. Therefore, soil management for optimal utilization and reduce its degradation is essential. Mapping the rate of erosion and sediment yield and areas prioritization according to it is effective step for organization, the protection and utilization of the soil. The purpose of this study was estimating amount of soil erosion and then simulate the effects of improvement and restoration on soil loss in the Lar area (Mazandaran).
Material and methods
Revised universal soil loss equation (RUSLE) was used within GIS. The parameters this model are consists of R, K, LS, C and P, respectively, that are calculated with using the data of rainfall, soil maps, digital elevation models and remote sensing techniques, respectively. Suitable location of improvement - restoration projects was determinate based on maps of slope, elevation vegetation, pedology and rangeland condition. Then, by combining theses maps and applying basic principles of range management for suggest appropriate methods, was offered rangeland management model for improving or maintaining the optimal status. Then erosion risk map was prepared using revised universal soil loss equation. Finally change of amount of erosion after restoration and reclamation operations was predicted using this model in GIS.
Results and discussion
The results showed that the mean values of parameters R, K, LS, C and P for study area was 67.143, 18.0, 52.5, 37.0 and 1, respectively. Average of yearly sediment load was estimated 51 ton/ha/year. Also the areas that to be allocated restoration and reclamation operations including 378 ha seeding, 246 ha inter seeding and 176 ha planting pile. Also cultivation on contour lines with seeding and strip cultivation with inter seeding was suggested and simulated. Simulation results after the suggested operations showed that the P and C factor will 0.8 and 0.31 respectively, therefore erosion mean will be reduced to 34 ton/ha/year and following that is equivalent 34% reduction. RUSLE model were used by many researchers in Iran and out of Iran (Asadi, et al. 1389, Vaezi, et al. 1389, Fiona, et al. 2010, Nijel, et al. 2010, Zangh, et al. 2010) and was confirmed its performance according this research. Results showed that areas with low slop had sediment rate than other areas. Average of yearly sediment load was zero to 595 ton/ha/year in study area. Soil erosion was more in eastern south parts of watershed rather than other parts, similar to results of Asadi, et al. 1389. Restoration and reclamation operations have changed C factor that can caused reduction of erosion. After simulation these operations had reduced erosion amount zero to 464 ton/ha/year, similar to results of Ligdi & Morgan, 1995, Terranva, et al. 2009, Stevens, et al. 2009.
Conclusion
Simulation results after the suggested operations showed that the P and C factor will 0.8 and 0.31 respectively, therefore erosion mean will be reduced to 34 ton/ha/year and following that is equivalent 34% reduction that indicates the importance of improvement - restoration projects within rangelands. Combination of GIS with sediment and erosion models is the effective method for determination of spatial distribution of sediment and erosion. Suggested improvement – restoration operations in addition to protection of water and soil will caused increase of forage product and following it increase of livestock product and increase of household income.
