| 摘要: |
| 【目的】探究氮沉降和降雨变化对华西雨屏区天然常绿阔叶林土壤呼吸的影响。【方法】通过野外原位试验，设置氮沉降(N)、减少降雨(R)、增加降雨(W)和对照(CK)4个处理，对天然常绿阔叶林土壤呼吸速率、0～10 cm土层土壤温度和土壤体积含水量进行为期1年的观测，并对以上3项指标的相关性进行分析，然后在试验处理的第13个月测定微生物生物量C、N含量。【结果】(1)N、R和W处理的平均土壤呼吸速率分别比CK降低了29.53%，12.26%和21.18%，各处理均显著抑制了常绿阔叶林土壤呼吸速率（P＜0.05）。(2)N、R、W和CK的土壤呼吸年通量分别为1 489.85，1 854.85，1 666.32和2 114.11 g/m2，N、R和W处理均显著减少了土壤呼吸年通量(P＜0.05)。(3)N、R、W和CK的Q10（土壤呼吸对温度的敏感系数）值分别为2.37，2.98，2.43和2.53。减少降雨可能使土壤呼吸的温度敏感性升高，氮沉降和增加降雨则降低了土壤呼吸的温度敏感性。(4)分别采用指数模型和一元二次项方程拟合土壤呼吸速率与温度和体积含水量间的回归方程，表明土壤温度能解释土壤呼吸月动态变化的83.08%～94.67%，土壤体积含水量能解释土壤呼吸月动态变化的63.06%~67.30%。(5)与CK相比，N、R、W处理的微生物生物量C、N含量均显著降低。【结论】氮沉降、增加降雨和减少降雨处理均显著抑制了华西雨屏区天然常绿阔叶林的土壤呼吸。在模拟氮沉降和降水变化下，与土壤水分相比，土壤温度是该区常绿阔叶林土壤呼吸的主要影响因素。 |
| 关键词: 氮沉降 降雨 土壤呼吸 天然常绿阔叶林 |
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| 基金项目:国家“十二五”科技支撑计划项目(2010BACO1A11);四川省“十二五”农作物育种攻关项目(2011NZ0098-10) |
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| Effects of nitrogen deposition and precipitation change on soil respiration in natural evergreen broad-leaved forest in the Rainy Area of Western China |
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ZHOU Shixing,HUANG Congde,XIANG Yuanbin,et al
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| Abstract: |
| 【Objective】The objective was to clarify the effects of nitrogen deposition and precipitation change on soil respiration in an evergreen broad leaved forest in the Rainy Area of Western China. 【Method】Four treatments of high nitrogen deposition (N),water reduction (R),water addition (W),and the control (CK) were set in Yucheng District,Yaan,Sichuan.Soil respiration,soil temperature at the depth of 0-10 cm and soil moisture were measured for 1 year using LI 8100( LI COR,Lincoln,NE,USA).The correlation of these 3 indexes was analyzed,and the contents of microbial C and N were determined 13 months after treatments.【Result】(1) The averaged soil respiration rates of N,R,and W treatments were 29.53%,12.26% and 21.18% lower than the control,respectively (P<0.05).(2) The cumulative soil CO2 efflux rates of N,R,and W treatments were 1 489.85,1 854.85,and 1 666.32 g/m2,showing significant decrease comparing with the CK (2 114.11 g/m2)(P＜0.05).(3) The Q10 values of N,R,W and CK treatments were 2.37,2.98,2.43 and 2.53,which indicated that N and W treatments reduced the temperature sensitivity of soil respiration to soil temperature while R treatment increased it.(4) The regression equations between soil respiration rate with soil volumetric water content, and soil temperature were fitted by exponential model and quadratic equation.The soil volumetric water content could explain 63.06%－67.30% of the monthly change of soil respiration,while the soil temperature explained 83.08%－94.67%.(5) Compared with CK treat ment,N,R,and W treatment significantly reduced the contents of microbial biomass C and N.【Conclusion】Nitrogen deposition, water reduction and water addition significantly inhibited soil respiration rate in natural evergreen broad leaved forest in the Rainy Area of Western China.Under simulated N deposition and precipitation changes,soil temperature is the main factor. |
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