The Effect of Crataegus pseudomelanicarpa Pojark. Canopy on Soil Total Carbon and Particulate Organic Matter in Grazed and Ungrazed Areas in Alborz Rangelands, Noor County, Iran

Trees and shrubs can act as nurse plants that facilitate the growth and development of other herbaceous species under their canopies and induced the autogenic development of soil parameters. Therefore, we studied the effect of Crataegus pseudomelanicarpa on soil carbon sequestration (total soil carbon and particulate organic matter) in two grazed and ungrazed areas during the two seasons (spring and autumn) in central Alborz, Pasperes village, Noor rangelands, Iran. Fifteen individual trees (according to the surface of each region, five in the ungrazed and ten in the grazed areas) were selected. Soil samples were taken in spring and autumn in 2017 under woody canopy (patch) and outside the canopy (interpatch) of individual trees. Soil samples were tested for Total Carbon (TC) and Particulate Organic Matter (POM). The results showed that the value of TC was higher in the autumn than the spring and conversely, POM was significantly higher in spring than autumn. Generally, the results showed that the presence of the shrubs in both grazed and ungrazed areas improved the values of TC and POM in both seasons. In the grazed area, POM (24.43 g kg-1 vs. 15.41 g kg-1 in the spring and 11.71 g kg-1 vs. 8.59 g kg-1 in the autumn) and TC (1.53% vs. 1.35% in the spring and 1.61% vs. 1.58% in the autumn) had significantly higher values in patches than interpatches while in the ungrazed area, these differences were less pronounced or not significant between patches and interpatches. It was concluded that the facilitated role of woody species in the conservation of soil carbon is more prominent in the grazed compared with ungrazed grasslands. It emphasized conservation of woody species in the rangelands particularly in the grazed areas.