[Short-term effects of low intensity thinning simulated by gap on ground microclimate and soil nutrients of pure spruce plantation].

Taking a dense spruce pure plantation as test object and simulating the formation of natural forest gap, this paper studied the effects of low intensity thinning by gap creation on the ground temperature, ground humidity, and nutrient contents in different soil layers of the plantation. In the first year of gap creation, the mean diurnal temperature in the gap across the growth season (May-September) increased, while the mean diurnal humidity decreased. The soil organic matter (SOM) and NH4+-N contents in O-horizon (humus layer) increased by 19.62% and 283.85%, and the dissolved organic carbon (DOC) and NO3--N contents decreased by 77.86% and 23.60%, respectively. The SOM, total nitrogen (TN), and NO3--N contents in 0-10 cm soil layer increased by 45.77%, 37.14%, and 75.11%, and the NH4+-N, DOC, and total phosphorus (TP) contents decreased by 48.56%, 33.33%, and 13.11%, respectively. All the results suggested that low intensity thinning by gap creation could rapidly improve the ground microclimate of the plantation, and consequently, promote the soil microbial activity and mineralization processes in O-horizon, the release of soil nutrients, and the restoration of soil fertility.