Distribution And Mineralization Characteristics Of Forest Soil Organic Carbon And Nitrogen

The mineralization of soil organic carbon(C) and nitrogen(N) are crucial for regulating terrestrial ecosystem nutrient cycling especially in forest ecosystems, and attracting great attentions. This study aimed at organic carbon content, organic nitrogen content, mineralizing characteristics, and their relationship with soil depth. Studies for the correlativity between carbon and nitrogen content with mineralizing characteristics can provide theoretical foundation to soil carbon and nitrogen cycling, as well as nutrient transfer process. The main conclusions are as follows:1. Soil organic C and N, soil aggregates, as well as cumulative mineralization of soil organic C(SOC) and N in 0-10 cm soli layer were significant higher than those in 10-20 cm soil layer. The mineralization ratio(Cp/C0) and potential mineralization ratio(Cp) of soil organic C, as well as soil organic N mineralization ratio(Nmin/N0) in 0-10 cm and 10-20 cm soil layers had no significant differences. The soil organic C mineralization rate(k) ranged from 1.21 to 2.52×10-2day-1, the differences between soil depths were not significant in 12 sites except for Harbin, Hainan and Liupan Mountain.2. Both cumulative mineralization of SOC and Cp values of all soils under N treatment were greater than CK group. The k value of N treatment group was smaller than CK group. N treatment could promote the cumulative amount of soil organic C mineralization, while had no effects on mineralization rate.3. There was positive correlation between cumulative mineralization of SOC, Cp and soil organic C. The mineralization ratio and Cp/C0 were negatively related to soil organic C. The soil organic C mineralization increased with increasing soil organic C content. In contrast, k decreased with soil organic C content.4. Compared with soil nitrate nitrogen, ammonium nitrogen had greater contributions to soil organic N mineralization. Soil organic N mineralization had a high correlation with total organic N. The soil organic N mineralization ratio(Nmin/N0) was negatively related to soil total organic N. The soil organic N mineralization increased with increasing soil organic N content. In contrast, mineralization ratio decreased with soil organic N content.