降水量对连古城自然保护区荒漠植被凋落物分解和氮状态的影响

对连古城自然保护区不同降雨梯度（不截留和分别截留30%、50%、80%）下荒漠典型植被土壤无机氮和原位净氮矿化的凋落物分解和养分释放进行了连续的观测分析。结果表明：（1）随着水分输入减少，凋落物的分解速率减小，凋落物分解速率与年降水量正相关。与此相反，净氮矿化与降水量无关。（2）土壤NO{}_{\mathrm{3}}^{-}浓度随着降水输入的增加而显著降低，而土壤NH{}_{\mathrm{4}}^{+}浓度在不同降水截留处理条件下并无显著差异。（3）在连古城自然保护区，荒漠植被凋落物分解速率与实际降雨量密切相关，并且在不同控制条件下，随时间的变化凋落物中的碳和氮含量存在同时流失的现象。

Effects of water input on litter decomposition and nitrogen dynamics of desert vegetation in the Liangucheng National Nature Reserve,Gansu,China

Based on the rainfall interception experiment of four different rainfall gradients(control and three lev‐els:interception of 30%,50%and 80%)in Liangucheng National Nature Reserve,the litter decomposition and nutrient release of inorganic soil nitrogen and in-situ net nitrogen mineralization of typical desert vegetation were observed and analyzed in two consecutive years.The main results are:(1)With the decrease of water input,the decomposition rate of litter also decreased,and there was a positive correlation between litter decomposition rate and annual precipitation.On the contrary,net nitrogen mineralization has nothing to do with precipitation.(2)Soil NO₃^-significantly decreased with increasing precipitation input,whereas soil NH₄⁺concentration did not differ among precipitation interception treatments.(3)In Liangucheng National Nature Reserve,the decomposi‐tion rate of desert vegetation litter is closely related to the actual rainfall,and under different control conditions,the content of carbon and nitrogen in the litter changes with time.