模拟氮沉降对华西雨屏区慈竹林土壤呼吸的影响

2007年12月至2008年11月,在华西雨屏区采用0(对照)、50、150、300kg.hm-2.a-1施氮处理和红外CO2分析法,研究了模拟N沉降对慈竹林土壤呼吸特征的影响.结果表明:慈竹林土壤呼吸速率年内季节变化呈明显的单峰型曲线,7月末最高,为(3.36±0.20)μmol.m-2.s-1,2月末最低,为(0.33±0.07)μmol.m-2.s-1.土壤呼吸速率与土壤温度之间呈极显著指数相关(P0.001),10cm深的土壤温度解释了土壤呼吸速率季节变化的91.6%;而土壤含水量与土壤呼吸之间相关性不显著(R2=0.0758).2008年6—11月根呼吸对土壤总呼吸的贡献率在46%～59%.50、150和300kg.hm-2.a-1施氮处理的年CO2释放量分别比对照低23.6%、46.7%和50.5%.0、50、150和300kg.hm-2.a-1施氮处理的土壤呼吸速率Q10值分别为3.72、3.51、2.95和2.71.

Effects of simulated nitrogen deposition on soil respiration in a Neosinocalamus affinis plantation in rainy area of west China

From December 2007 to November 2008, an in situ experiment was conducted to study the effects of simulated nitrogen deposition on the soil respiration in a Neosinocalamus affinis plantation in Rainy Area of West China. Four treatments were installed, i.e., 0 (CK), 50, 150, and 300 kg N x hm(-2) x a(-1), and soil respiration rate was measured by infrared gas analyzer. In the test plantation, soil respiration rate had a distinct seasonal fluctuation, with the highest (3.36 +/- 0.20 micromol x m(-2) x s(-1)) by the end of July and the lowest by the end of February (0.33 +/- 0.07 micromol x m(-2) x s(-1)). There was a significant exponential relationship (P<0.001) between soil respiration rate and soil temperature, and the temperature at 10 cm soil depth explained 91.6% of the seasonal change of soil respiration. However, less relationship was observed between soil respiration rate and soil moisture content (R2 = 0.0758). From June to November 2008, the contribution of root respiration to total soil respiration ranged from 46% to 59%. The annual release amount of CO2 in treatments 50, 150, and 300 kg x hm(-2) x a(-1) was 23.6% , 46.7%, and 50.5% lower than that in CK (2.17 x 10(4) kg x hm(-2)), and the Q10 value of soil respiration rate in treatments 0, 50, 150, and 300 kg x hm(-2) x a(-1) was 3.72, 3.51, 2.95, and 2.71, respectively.