土壤湿度对鲁东南杨树人工林地土壤呼吸的影响

摘要

【Objective】 The objective was to clarify the effects of soil moisture on soil respiration in Populus tremula plantations in Southeast Shandong.【Method】 Soil respiration,heterotrophic respiration and autotrophic respiration had been measured with portable infrared CO2 gas analyzer(GXH-3051) combined with homemade closed chamber in middle-aged Populus tremuloides plantation and mature Populus tremuloides plantation in Benghe Forest Farm for two years(2010-2011).Soil temperature and soil moisture were also measured simultaneously.【Result】 The soil respiration in middle-aged Populus tremuloides plantation and mature Populus tremuloides plantation showed distinct seasonal dynamics with unimodal curve.Soil respiration was highest in July and lowest in January.The maximum rates of soil respiration in middle-aged Populus tremuloides plantation and mature Populus tremuloides plantation were 4.43 and 3.55 μmol/(m2·s),respectively while the minimum rates were 0.72 and 0.54 μmol/(m2·s),respectively.Similar to soil respiration dynamics,autotrophic respiration showed remarkable fluctuation.In contrast with soil respiration,soil heterotrophic respiration and soil moisture showed more complex variation.Correlations between soil respiration,autotrophic respiration,soil heterotrophic respiration and soil moisture were all linear.The correlation between soil respiration and soil moisture was highest for the middle-aged Populus tremuloides plantation(r2=0.750 3).【Conclusion】 Correlations between soil respiration,heterotrophic respiration,autotrophic respiration and soil moisture were linear.However,the influencing mechanism was complex.%【目的】探究土壤湿度对鲁东南杨树人工林地土壤呼吸的影响。【方法】2010-2011年,利用GXH-3051便携式红外CO2气体分析仪结合自制的密闭箱,对中龄杨树人工林地和成熟杨树人工林地的土壤呼吸速率及土壤自养、异养呼吸速率进行测定,同时测定土壤表层0～10cm的含水量。【结果】2010和2011年,中龄杨树人工林地和成熟杨树人工林地的土壤呼吸速率均呈单峰变化,夏季（5-7月）土壤呼吸速率较高,并于7月达到高峰,中龄和成熟杨树人工林地土壤呼吸速率最大值分别为4.43和3.55μmol/（m2.s）,冬季（12月-次年2月）土壤呼吸速率较低,并于1月达到最低值,中龄和成熟杨树人工林地土壤呼吸速率最小值分别为0.72和0.54μmol/（m2.s）。土壤自养呼吸速率季节变化趋势与土壤呼吸速率相似,而异养呼吸速率变化趋势则较复杂。土壤湿度的季节波动与土壤呼吸及土壤各组分呼吸速率的变化不完全一致。可用线性模型来描述土壤呼吸速率、自养呼吸速率、异养呼吸速率与土壤湿度的关系,其中中龄杨树人工林地土壤呼吸速率与土壤湿度的相关性最高（r2=0.750 3）。【结论】土壤湿度与鲁东南杨树人工林地土壤各组分呼吸间存在线性关系,但影响机制比较复杂。