| 英文摘要: |
Nitrogen (N) addition can affect soil organic matter (SOM) decomposition by enhancing soil enzyme activity, increasing labile organic carbon (C) fractions and decreasing litter C/N ratio. This study was designed to investigate the short-term effect of N addition on litter and soil chemical and biological properties in Calamagrostis angustifolia freshwater marshes. A field experiment was conducted in which soil was treated with N addition of 0 (N0), 12 (N1), and 24 (N2) g N m(-2) year(-1), respectively. Above-ground biomass increased by 40 % and 32 % for N1 and N2 treatment, respectively. Added N increased litter C and N concentrations as well as beta-glucosidase and invertase activities. However, litter C/N ratio decreased with N addition. N1 treatment increased microbial biomass carbon (MBC) in both topsoil and subsoil, but no changes in dissolved organic carbon (DOC) were observed. Total N concentrations in subsoil increased both in N1 and N2 treatments; NH4 (+)-N decreased in the N1 treatment, while NO3 (-)-N increased in the N2 treatment in topsoil. N2 treatment increased beta-glucosidase, invertase, and urease activities in both soil layers. The differences in litter and soil characteristics caused by N addition suggest that N addition has the capacity to increase soil C transformation rates in marshland. |
