2008年1月至2009年2月,对华西雨屏区撑绿杂交竹(Bambusa pervariabilis×Den-drocala mopsi)人工林进行模拟氮沉降试验,氮沉降水平分别为对照(CK,0 g N·m-2·a-1)、低氮(5 g N·m-2·a-1)、中氮(15 g N·m-2·a-1)和高氮(30 g N·m-2·a-1),采用红外CO2分析法测定土壤呼吸速率.结果表明:杂交竹林土壤呼吸呈明显的季节变化,7月最高,1月最低.对照样方土壤呼吸年累积量为(389±34)g C·m-2·a-1.土壤呼吸速率与10 cm土壤温度和气温呈极显著正指数关系,与微生物生物量碳、氮呈极显著正线性关系.模拟氮沉降显著促进了土壤呼吸,低氮、中氮处理与对照之间差异达显著水平,但高氮处理与对照之间差异不显著.自然状态下,杂交竹林土壤表层微生物生物量碳和氮分别为0.460和0.020 mg·g-1,而所有氮处理中土壤微生物生物量碳和氮均显著增加.杂交竹林土壤表层(0～20 cm)细根密度为388 g·m-2,模拟氮沉降对杂交竹林细根密度的影响不显著.基于土壤10 cm深度温度和空气温度计算的杂交竹林土壤呼吸Q10值分别为2.66和1.87,短期模拟氮沉降并未显著影响土壤呼吸温度敏感性.杂交竹林土壤呼吸变异主要受温度和微生物生物量的控制,模拟氮沉降可能通过增加土壤微生物生物量促进了该系统土壤CO2排放.
Effects of simulated nitrogen deposition on soil respiration in a Bambusa pervariabilis × Dendrocala mopsi plantation in Rainy Area of West China
From January 2008 to February 2009 . a field experiment was conducted in Rainy Area of West China to understand the effects of nitrogen ( N) deposition on the soil respiration in a Bambusa pervariabilis× Dendrocala mopsi plantation. Four treatments were installed. i. e. , no N added (control) , 5 g N·m-2· a-1(low-N), 15 g N · m-2 ·a-1(medium-N). and 30 g N·m-2 · a-1( high-N) , and soil respiration rate was determined by infra-red CO2 analyzer. In the plantation,soil respiration rate had an obvious seasonal change , with the maximum in July and the minimum in January. In control plot, the annual cumulative soil respiration was (389+34) g ·m-2 · a-1. Soil respiration rate had significant positive exponential relationships with soil temperature at 10 cm depth and air temperature, and significant positive linear relationships with soil microbial biomass carbon ( MBC) and nitrogen ( MBN) . Simulated N deposition promoted soil respiration significantly, with significant differences between the low- and medium-N and the control but no significant difference between high-N and the control. In control plot, surface soil (0-20 cm) MBC and MBN were 0. 460 and 0. 020 mg·g-1 ,respectively. In N-added plots. both the MBC and the MBN had significant increase. The fine root density in surface soil was 388 g·m-2. which was less affected by simulated N deposition. The soil respiration Q10 value calculated from soil temperature at 10 cm depth and air temperature was 2. 66 and 1. 87 , respectively . and short-term N deposition had lesser effects on the Q10 value. The variation of soil respiration in the plantation was mainly controlled by temperature and soil microbial biomass. and simulated N deposition could increase the CO2 emission via increasing soil microbial biomass.
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NSTL
万方数据
维普
