皆伐方式对小兴安岭低质林土壤呼吸的影响

Influence of the Clear-Cutting Pattern on Soil Respiraction in a Low-Quality Forest in Lesser Khingan Range

针对小兴安岭低质林分,采用不同的皆伐方式,利用LI-8100碳通量自动监测系统在春、夏、秋、冬4个季节对低质林分土壤呼吸进行观测,运用统计分析的方法,分析皆伐方式对土壤呼吸的影响和不同皆伐方式的土壤呼吸产生差异的原因。结果显示:试验区土壤呼吸夏季最大,冬季最低,春季和秋季因土壤温度和湿度差异不大使土壤呼吸相差较小;对于水平带同一条皆伐带,土壤呼吸并无显著性差异,并且不同的带宽对土壤呼吸的影响也不显著;垂直带随海拔升高土壤呼吸呈现波动性,总体趋势随海拔升高土壤呼吸逐渐降低,但是差距较小;水平带、垂直带和林窗的年土壤呼吸量分别为1.184,1.426,1.179kgCO2.m-2a-1,垂直带最高,水平带次之,林窗最低。影响垂直带土壤呼吸的关键因素是土壤温度,林窗则是土壤湿度,而水平带土壤温度和湿度的条件则介于垂直带和林窗之间。这说明在不同的皆伐方式条件下,影响土壤呼吸的关键因素并不完全相同。

Different clear-cutting patterns were executed in low-quality forest stands of Lesser Khingan Range in spring,summer,autumn and winter.Soil respiration of the low-quality forest stands was recorded by using a LI-8100 CO2 flux automatic monitoring system.Influence of the clear-cutting pattern on the soil respiration and the reasons causing differences in the soil respiration with different clear-cutting patterns were investigated and analyzed with statistical analyses.The results showed that the soil respiration was the biggest in summer and the lowest in winter at the experimental area.Less difference in the soil respiration in the spring and autumn was noticed likely due to little difference in soil temperature and moisture content.Within a belt of horizontal zone,there was no significant difference in the soil respiration,and the different band widths had no remarkable influence to the soil respiration.The soil respiration along elevation in vertical clear-cutting zone fluctuated,but the overall tendency was decreasing in the soil respiration with increased altitude.The soil respiration annually released 1.184,1.426,and 1.179 kg CO_2·m-2 a-1 in horizontal zone,vertical zone and forest gap,respectively.Soil temperature was the key factor affecting the soil respiration in vertical zone while in forest gaps the key factor was the soil moisture.The soil temperature and moisture content in horizontal zone lied in between vertical zone and forest gap.This indicated that in the condition of different clear-cutting patterns,the key factor affecting the soil respiration was not in the same.