毛白杨人工林生长季根呼吸特征研究

Characteristics of Root Respiration in Growing Period of Populus tomentosa Plantations

阐明渭河沿岸区2块不同年龄毛白杨人工林根呼吸特征及其环境因子之间的关系。2014年5-10月,利用Li-6400设备结合挖壕法测定退耕还林后40年毛白杨人工林(样地Ⅰ)及退耕5a毛白杨与84K杨混交林(样地Ⅱ)的生长季根呼吸速率动态变化与地下10cm处土壤温湿度。结果表明,2块样地的生长季根呼吸速率变化具有明显的月动态,月均值变化趋势均呈单峰曲线;样地Ⅰ与样地Ⅱ的根呼吸生长季平均贡献率分别为25.64%、25.26%,根呼吸速率月均变化范围分别为0.48~1.44μmol/(m2·s)、0.38~1.18μmol/(m2·s),生长季均值分别为0.87、0.79μmol/(m2·s);样地Ⅰ与样地Ⅱ的根呼吸速率与其对应土壤温度呈极显著的相关关系(p<0.01),地下10cm处的Q10值分别为4.22和4.45,样地Ⅰ根呼吸速率与土壤湿度无显著相关关系(p>0.05),样地Ⅱ土壤呼吸速率与土壤湿度间有显著的负相关关系。影响2块样地的根呼吸速率的最主要因子是土壤温度,样地Ⅰ根呼吸速率的温度敏感性小于样地Ⅱ。

The study was to clarify the characteristics of root respiration and its relationship with environmental factors in growing period of Populus tomentosa plantations with different ages in the region of Weihe River.Root respiration rates and temperature-humidity of soil at 10 cm depth in growing period in40-year-old P.tomentosa plantation(sample plotⅠ)and 5-year-old P.tomentosa+84Kplantation(sample plotⅡ)after returning farmland to forest were measured by trenching and Li-6400 system from May to October in 2014.Results showed that the root respiration rates had a significant monthly dynamic changes with unimodal curves in sample plotⅠandⅡ.The average contributions of root respiration rates of plot I and II were 25.64% and 25.26%,respectively.The average monthly rates of root respiration ranged 0.48~1.44μmol/(m2·s)and 0.38~1.18μmol/(m2·s).The average rates in growing period were 0.87and0.79μmol/(m2·s).The relationships between root respiration and soil temperature at 10 cm depth could be described by exponential equations in the sample plotⅠandⅡ,and the Q10 value were 4.22 and 4.45,respectively.There was no significant correlation between root respiration and soil moisture in the sample plotⅠ,but in the sample plotⅡ,there was significant and negative correlation among them.Main factor affecting the root respiration was soil temperature at 10 cm depth in two sample plots.Root respiration in sample plotⅠwas lower in temperature sensitivity than in sample plotⅡ.