环境因子对沿海防护林土壤呼吸季节动态的影响

Effects of environmental factors on seasonal dynamics of soil respiration in coastal protection forests

为探究闽南沿海地区人工防护林土壤呼吸速率的季节动态特征及其对土壤温度和湿度季节变化响应,以滨海沙地纹荚相思、尾巨桉、肯氏相思、木麻黄和湿地松防护林为研究对象,采用Li-8100自动土壤CO_(2)通量测量系统测定各林地不同季节的土壤呼吸速率,同时测定土层10 cm深处的土壤温度和湿度。结果表明:5种典型人工防护林土壤呼吸速率的季节平均值依次为尾巨桉林(3.51 μmol·m^(-2)·s^(-1))>纹荚相思林(3.33 μmol·m^(-2)·s^(-1))>木麻黄林(3.02 μmol·m^(-2)·s^(-1))>肯氏相思林(2.95 μmol·m^(-2)·s^(-1))>湿地松林(2.06 μmol·m^(-2)·s^(-1)),均表现出夏季高、冬季低的季节变化特征。湿地松林土壤呼吸速率与土壤温度显著相关(P<0.05),另外4种防护林土壤呼吸速率与土壤温度均极显著相关(P<0.01);纹荚相思林土壤呼吸速率与土壤湿度极显著正相关(P<0.01),另外4种防护林土壤呼吸速率与土壤湿度均不显著相关(P>0.05)。5种防护林的土壤呼吸速率对温度敏感性系数(Q_(10)值)存在差异,4种阔叶林Q_(10)值均大于针叶林(湿地松林)。研究发现,不同类型防护林土壤呼吸速率均存在差异,土壤温度是影响该地区土壤呼吸速率季节变化的主要环境因子。

To explore the seasonal dynamic characteristics of soil respiration rate and its response to seasonal changes of soil temperature and humidity in an artificial shelterbelt in the coastal areas of southern Fujian, coastal sandy lands with Acacia aulacocarpa protection forests, Eucalyptus urophylla×Eucalyptus grandis protection forests, Acacia cunninghamia protection forests, Casuarina equisetifolia protection forests, and Pinus elliottii protection forests were studied. The Li-8100 automatic soil CO_(2) flux measurement system was used to measure the soil respiration rate at different seasons in each forest land, and the soil temperature and humidity at a depth of 10 cm were measured simultaneously. The results showed that the seasonal mean values of soil respiration rate in the five typical protection forests were in the order of E. urophylla×E. grandis(3.51 μmol·m^(-2)·s^(-1))>A. aulacocarpa(3.33 μmol·m^(-2)·s^(-1))>C. equisetifolia(3.02 μmol·m^(-2)·s^(-1))>A. cunninghamia(2.95 μmol·m^(-2)·s^(-1))>P. elliottii(2.06 μmol·m^(-2)·s^(-1)), all of which showed seasonal variations during high summer and low winter. There were significant exponential correlations between the soil respiration rate and soil temperature in P. elliottii protection forest(P<0.05), and extremely significant exponential correlations between soil respiration rates and soil temperatures in the other four types of protection forests(P<0.01). In addition, there were extremely significant positive correlations between soil respiration rate(P<0.01), and soil moisture content in A. aulacocarpa protection forest and non-significant correlations between soil respiration rates and soil moisture contents in the other four types of protection forests(P>0.05). The sensitivity coefficient(Q_(10)) of soil respiration rate to temperature differed among the five types of protection forests, and the Q_(10) values of the four broadleaf forests was greater than that of the coniferous forest(P. elliottii). The soil respiration rates differed in the five types of protection forests, and soil temperature was the main environmental factor affecting seasonal changes in soil respiration rates in the region.