长白山阔叶红松林皆伐迹地土壤呼吸作用

SOIL RESPIRATION IN A CLERA-CUT BROAD-LEAVED KOREAN PINE FOREST OF CAHNGBAI MOUNTAIN

利用静态箱式法测量长白山阔叶红松(Pinus koraiensis)林伐后13年的皆伐迹地土壤呼吸作用。分析表明,皆伐迹地土壤呼吸作用日变化趋势呈单峰曲线,峰谷值出现时间较林地提前2～4h,与土壤5cm深度温度变化趋势基本一致。整个生长季节皆伐迹地土壤呼吸速率约为林地的75%,土壤温度与土壤呼吸作用存在显著的指数关系。在降水量集中的生长季,土壤水分对土壤呼吸作用具有一定的抑制作用,利用温度和水分双因子模型可以较好地解释皆伐迹地土壤呼吸作用的变异。阔叶红松林皆伐后生物量减少和微环境变化是造成土壤呼吸作用强度和动态特征发生变化的重要原因。

Aims Soil respiration is the second largest flux in the global carbon cycle. Human activity, especially forest cutting, had brought a lot release of soil carbon. But the effect of forest clear-cutting on soil respiration was not inadequately understood. We chose Korean pine forest in Changhai Mountain as the case study area. Our aim is to compare soil respiration in clear-cut fields with that in natural Korean pine forests, and to reveal the effects of clear-cut on the density and pattern of soil respiration. Methods During the growing seasons from 2003 to 2005, soil respiration was measured by a closed static chamber system in the clear-cut fields and Korean pine forests in Changhai Mountain. Soil temperature and moisture during the upper layers were observed by geothermometer and TDR system. Important findings The results showed that diurnal variation of soil respiration at clear-cut plot could be expressed as single peak curve, and the times of the maximum and the minimum soil respiration values appeared 2 - 4 hours earlier than those in forest plot, which consisted with that of soil temperature at 5 cm depth. Soil respiration rate at forest plot was higher with the proportion of 75 % than that in clear-cut plot during the growing season. Soil temperature had a significant exponential relationship with soil respiration. Soil water may have negative effect on soil respiration during the growing season with high frequency precipitations. The soil respiration model including the effects of soil water and temperature could explain soil respiration variation much better than temperature-based soil respiration model. The management of clear-cut forest had obvious effect on the dynamic characteristics and intensity of soil respiration due to the decrease in biomass and the change in microclimate in Korean pine forest.