模拟酸雨对次生林土壤呼吸及异养呼吸的影响

Effects of Simulated Acid Rain on Soil Respiration and Heterotrophic Respiration in a Secondary Forest

为研究模拟酸雨对次生林土壤呼吸及异养呼吸的影响,进行野外定位试验.设置裂区试验,分4个区组,每个区组中主区为不断根和挖沟断根小区,每个主区内设置对照(CK)、pH 4.0(A1)、pH 3.0(A2)、pH 2.0(A3)共4个模拟酸雨处理水平.观测不断根小区的土壤呼吸和断根小区的异养呼吸,同时观测土壤温度、土壤湿度.结果表明,在不断根小区,CK、A1、A2、A3处理的土壤呼吸均表现出明显的季节变异趋势;与不断根小区类似,断根小区的异养呼吸也具有明显的季节变异趋势.断根小区的异养呼吸明显低于不断根小区的土壤呼吸.CK、A1、A2、A3处理的年平均土壤呼吸速率分别为(2.47±0.31)、(2.52±0.22)、(2.38±0.17)、(2.43±0.22)μmol·(m^2·s)^(-1);断根小区CK、A1、A2、A3处理的年平均异养呼吸速率分别为(1.55±0.10)、(1.65±0.22)、(1.77±0.08)、(1.78±0.27)μmol·(m^2·s)^(-1).单因素方差分析表明,不断根小区不同模拟酸雨处理之间的土壤呼吸速率以及断根小区不同模拟酸雨处理的异养呼吸速率均无显著差异.回归分析表明,不断根小区的土壤呼吸与断根小区的异养呼吸之间存在极显著(P<0.001)的正比例函数关系,模拟酸雨的添加降低了土壤呼吸与异养呼吸之比.土壤温度是决定不断根小区土壤呼吸和断根小区异养呼吸季节变异的最主要的因素,而土壤湿度对土壤呼吸和异养呼吸的季节变异无显著的影响.

In order to investigate the effects of simulated acid rain on soil respiration and heterotrophic respiration in a secondary forest,a field experiment was carried out. A split-plot experiment was arranged in field. There were 4 blocks; each block had two main plots which were trenched and un-trenched plots. In each main plot,4 simulated acid rain treatments of control（ CK）,pH 4. 0（ A1）,pH3. 0（ A2）,and pH 2. 0（ A3） were randomly assigned. Soil respiration in the un-trenched plots and heterotrophic respiration in the trenched plots were measured weekly. Soil temperature and moisture at a depth of 5 cm were measured during the respiration measurements. The results indicated that different simulated acid rain treatments exhibited similar seasonal patterns of soil respiration and heterotrophic respiration. Heterotrophic respiration in the trenched plots was significantly lower than soil respiration in the untrenched plots. The annual mean soil respiration rates for the CK,A1,A2,and A3 treatments in the un-trenched plots were（ 2. 47 ±0. 31）,（ 2. 52 ± 0. 22）,（ 2. 38 ± 0. 17）,and（ 2. 43 ± 0. 22） μmol·（m2·s）-1,respectively,while the annual mean heterotrophic respiration rates for the 4 treatments in the trenched plots were（ 1. 55 ± 0. 10）,（ 1. 65 ± 0. 22）,（ 1. 77 ± 0. 08）,and（ 1. 78 ± 0. 27）μmol·（m2·s）-1,respectively. ANOVA showed that simulated acid rain had no significant effects on soil respiration in the un-trenched plots and heterotrophic respiration in the trenched plots. Regression analysis suggested that there was a significant linear regression relationship between soil respiration and heterotrophic respiration. Simulated acid rain significantly（ P〈 0. 001） decreased the ratio of soil respiration to heterotrophic respiration. Soil temperature was the main controlling factor regulating the seasonal patterns of soil respiration and heterotrophic respiration for each of the SAR treatment,while soil moisture had no significant effects on the seasonal variability in soil respiration and heterotrophic respiration.