亚热带常绿阔叶林根系呼吸及其与环境影响因子的关系

Root Respiration of Subtropical Evergreen Broad-Leaved Forests and Its Relationship with the Environment Impact Factors

采用切断根系法,运用Li-6400光合呼吸测定仪对肖坑亚热带常绿阔叶林根系呼吸特性及其对土壤呼吸的贡献和季节动态变化进行了研究,并探讨了根系呼吸对土壤温度和含水量的响应。结果表明,中龄林根系呼吸速率年变化范围为0.412～1.970μmol/(m^2·s),幼龄林为0.259～1.414μmol/(m^2·s);幼龄林年平均根系呼吸速率(1.198μmol/(m^2·s))是中龄林的(0.937μmol/(m^2·s))1.13倍。中龄林和幼龄林根系呼吸速率及根系呼吸占土壤总呼吸的比例季节变化规律基本一致,1年中基本呈单峰曲线模式,高峰值出现在6月,之后逐渐下降至次年1月达最低值。幼龄林根系呼吸占土壤总呼吸的比例为31.79%～59.00%;而中龄林根系呼吸所占比例范围(23.50%～50.26%)较幼龄林小。中龄林和幼龄林根系呼吸速率与土壤5cm内温度相关性显著。中龄林根系呼吸对土壤温度的敏感程度大于幼龄林。在温度较低的情况下,土壤高含水量并没有促进根系的呼吸,但与土壤温度互作可能对林木根系呼吸产生较为显著的促进效果,这方面还需进一步研究。

In order to understand the role of root respiration in forest ecosystems,root and soil respiration rate and seasonal dynamic change in a subtropical forest were studied using Li-6400 CO2 analyzer in different development stages of the subtropical evergreen broad-leaved forest in Xiaokeng forested watershed of Southern Anhui. At the same time, we .have discussed root respiration rate to the soil temperature and moisture content at 5cm soil layer. The results showed that the root respiration rate of mid-aged was in the range of 0.259 -1.414μmol/（m^2.s ） and that of young stand was 0. 412 1. 970μmol/（m^2.s ）, respectively. The annual average rate of root respiration of young stand （1. 198μmol/（ m^2.s ） ） was 1.13 times as great as that of mid-aged stand （0. 937μmol/（ m^2.s ））. The root respiration of mid-aged stand and young stand showed similar seasonal change. The percentage of root respiration to soil total respiration also showed the same patterns in both young and mid-aged stands. The root respiration rate of young stand was significantly higher than that of mid-aged stand. The proportion of root respiration to soil total respiration in young stand was in range of 31.79% - 59.00% ,while 23.50% -50.26% in mid-aged stand. The root respiration in both mid-aged and young stands were significantly correlated to soil temperature at 5cm. The root respiration of mid-aged stand was much more sensitive to the soil temperature than the young stand. However,the root respiration was poorly related to the soil moisture. The interaction between soil moisture and temperature was likely to play a significant effect to promoting root respiration,which needs further study.