Soil carbon and nitrogen fractions in response to land use/cover changes

The effects of deforestation and land use/cover changes, i.e. Alnus subcordata and Cupressus sempervirens plantations, rice cultivation, and also deforested areas of Carpinus betulus-Parrotia persica on soil carbon (C) and nitrogen (N) fractions were evaluated in Hyrcanian region, northern Iran. Twelve samples per land use/cover were taken from the top 10 cm soil and characterized with respect to soil physico-chemical and biological properties. The fraction of C and N including microbial respiration (MR), microbial biomass C (MBC) and N (MBN), particulate organic matter C (POM-C) and N (POM-N), dissolved organic C (DOC) and N (DON), and N mineralization were measured. Land use/cover affected soil physico-chemical and biological properties. Higher values of MR were observed under Alnus (0.51 mg CO2-C g soil(-1) day(-1)) whereas the amount of MBC (711.73 mg kg(-1)), POM-C (3.48 g kg(-1)) and DOC (82.31 mg kg(-1)) were significantly higher in Cupressus plantation. Soil N fractions (that is, mineralized N, MBN, POM-N, and DON) were significantly higher and lower under the Alnus and deforested areas (52.18-22.29 mg N kg soil(-1), 61.41-18.48 mg kg(-1), 0.49-0.22 g kg(-1), 33.23-13 mg kg(-1)), respectively. In conclusion, plantations of A. subcordata and C. sempervirens increased the soil C and N fractions in deforested areas of northern Iran and are recommended for rehabilitation of degraded natural forests in the region.