A field simulated experiment was conducted to study the effects of variation of precipitation on the fine root decomposition and related nutrient release in Picea schrenkiana var.tianshanica. Three precipitation treatments were designed as ZP (zero precipitation), CK (natural precipitation, control) and DP (double precipitation). The results showed that, (1) After 24 months decomposition, the fine root remain percentage in CK of Picea schrenkiana var.tianshanica is 0.80 times in ZP and 1.28 times in DP. The differences of fine root remain percentage under three precipitation treatments in the eighth month since beginning decomposition were not significant (P>0.05), while the difference were significant in other decomposition stages (P<0.05). The fine root decomposition coefficient was DP (0.30)>CK (0.22)>ZP (0.08). Compared with the required times for fine root decomposition 50%and 95%in CK, they were longer than 5.45a and 23.75a in ZP treatment, and shorter than 0.44a and 1.91a. The results indicated that increase precipitation promoted the fine root decomposition, while removal precipitation inhibited its decomposition. (2)The fine root monthly decomposition rate in CK and DP were double peak curves, while it was relatively smooth curve in ZP. And (3) precipitation treatment changed the decomposition model of lignin and cellulose of Picea schrenkiana fine root decomposition and release model of N element, but it did not change release model of C element.%采用野外模拟试验，通过设计3种降水变化处理[ZP（去除降水）、CK（自然降水，对照）、DP（双倍降水）]，研究了降水变化对天山云杉细根分解的影响。研究结果表明，分解24个月CK处理的细根干质量残留率分别是ZP和DP处理的80%和128%倍。除在分解进行到第8个月时，3种处理细根质量残留率差异不显著外（P>0.05），其余分解时期差异均显著（P<0.05）。3种处理下细根分解系数为DP（0.30）>CK（0.22）>ZP（0.08）。与CK处理下细根分解50%和95%的时间相比， ZP处理分别增加了5.47年和23.75年，DP处理分别减少了0.44年和1.91年，说明增加降水促进了天山云杉细根分解，而去除降水抑制了分解。CK和DP处理下细根月分解率表现为双峰型曲线，ZP处理则变化相对平稳的曲线。降水处理改变了细根分解过程中纤维素和木质素分解模式及N元素的释放模式，但对C元素的释放模式没有影响。
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