F. Raiesi Gahrooee, E. Asadi, J. Mohammadi,
Volume 9, Issue 3 (10-2005)
Abstract
Over-grazing may induce changes in the dynamics of plant residue carbon and soil organic carbon (SOC). The objective of this study was to evaluate the litter quality of three dominant pasture species, and the relationship between litter quality and C dynamics under different range managements in native rangelands of SabzKou. Aboveground litters from three dominant species including, Agropyron intermedium (AP), Hordeum bulbosum (HB) and Juncus stenophylla (JU) were collected in an area protected from grazing for 15 years. Concentrations of N, P and K in litter samples were determined. Litter decomposition was also studied by using a litter bag experiment. Bagged litters were incubated under field conditions at grazed and ungrazed sites for one year. Concentrations of N in litters were 1.37, 1.36 and 0.98, respectively, for AP, JU and HB. Assuming 50 % C in the litter, C/N ratios of litters were 37.2, 37.3 and 51.1, respectively, for AP, JU and HB. The litters of AP, JU and HB contained, respectively, 0.13,0.12 and 0.21 % of P, and 1.04, 1.01 and 1.72 % of K. Results indicate no significant (p>0.05) and consistent difference in litter decomposition rates between grazed and ungrazed areas. The three pasture species, however, showed significant (p<0.01) differences in litter decomposition rate. It is appearing that the trend in litter decomposition of these plant species correlates initially with litter C/N ratio, but other quality parameters of litter as well as soil environmental conditions would likely affect the litter decomposability in advanced stages of decomposition process.
F. S. Tarighat, Y. Kooch,
Volume 22, Issue 2 (9-2018)
Abstract
The effect of broad-leaved forest trees (Alnus glotinusa, Ulmus glabra, Popolus caspica and Parrotia persica) and their canopy position on soil C and N storage and mineraization in the plain forest areas of Noor was investigated. Soil samples were taken from two positions (near and away from the main stem) with the microplots of 30×30×15 cm. Litter (C and N), soil physical (bulk density, texture and water content), chemical (pH, EC, organic C, total N and available Ca), biochemical and biological (N mineralization and microbial respiration) characteristics were measured at the laboratory. Carbon mineralization rate (CMR) was calculated using the equation [incubation time period (hour) ×soil volume (gr) / CO2 amount (mol C)]. Soil C and N storage (ton/ha) was calculated by C and N contents, bulk density, and the soil sampling depth. The results showed that there was no significant difference between the C storage under the studied tree spcies, whereas N storage presented significantly greater amounts, under Alnus glotinusa (0.79 ton/ha) rather than Ulmus glabra, Popolus caspica and Parrotia persica (0.69, 0.45 and 0.21 ton/ha, respectively). The higher values of soil C (0.001 mol C/kg) and N (0.3 ml N/kg) mineralization were significantly recorded under Alnus glotinusa instead of tree species. Soil C and N storage and mineralization process were not affected by the sampling positions. According to the results, soil C and N storage and mineralization were influenced by litter quality and soil chemistry.
