Abstract:

With a LI-8100 system for monitoring soil canbondioxide flux and sensors for measuring soil temperature and moisture the soil partitioning respiration rate during growth seasons and the soil temperature and moisture at 10 cm depth were investigated after selective cutting in various cutting intensity sites at Dongfanghong Forest Farm of Dailing Forest Bureau. The respiration yearly changes of every plot were analyzed based on the investigation data. Because of influencing from the selective cutting，the results showed: 1) The annual respiration rate of litter layer soil during growth seasons was increased yearly and the mean of respiration rate of litter layer soil was correlated with the cutting intensity in quadratic pattern (R²=0.806); 2) The annual respiration rate of roots during growth seasons fluctuated during the four\|year investigation period，and the mean of respiration rate of roots was also correlated with the cutting intensity in quadratic pattern (R²=0.415); 3) the annual respiration rate of mineral soil during growth seasons was increased，but it was not correlated with the cutting density. The temperature and the moisture of soil were the two main factors to impact soil partitioning respiration. The litter layer soil and the mineral soil were two key compoments to reflect the soil respiration change after cutting. It is suggested that the selective cutting with moderate density (less than 52%) is the best option in order to reduce the CO₂ flux after harvest.

Key words: selective cutting, soil partitioning respiration, litter layer respiration, root respiration, mineral soil respiration