Abstract:

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 CO₂·m^-2a^-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.

Key words: low-quality forest, soil respiration, clear-cutting pattern, soil temperature, soil moisture