Analysis of Dynamic Changes of Litter and Soil Water Conservation Capacity in Chinese Fir Forest by Thinning

This study aimed to explore the effects of thinning years on the water holding capacity of litter layer and soil layer in Chinese fir forest, thus to provide a scientific basis for evaluating the response of water conservation function of Chinese fir forest to thinning. In Jingning County, southwest Zhejiang Province, the Chinese fir forest with thinning for 1 year, 3 years, 8 years and unthinning was selected as the research object, and the litter and soil samples were collected. Then, the moisture content, water holding capacity, soil bulk density, non-capillary porosity of litter were analyzed and measured, and the relevant indexes were calculated. The results showed that there was no significant difference in the litter stock on hand of Chinese fir forest among different thinning years （P＞0.05）. The relationship between litter water holding capacity, water holding rate and water immersion time was in accordance with logarithmic function and power function, respectively. The maximum water holding capacity, maximum retention rate and effective retention rate of litter layer in Chinese fir forest with thinning for 8 years were significantly higher than those in the unthinned forest （P＜0.05）. The maximum water holding capacity and effective retention rate of litter layer in Chinese fir forest with thinning for 3 years and 8 years were significantly higher than those in unthinned forest （P＜0.05）. After thinning for 8 years, the soil bulk density of 0-10 cm soil layer in Chinese fir forest was significantly decreased （P＜0.05）, the non-capillary porosity was significantly increased, and the non-capillary water holding capacity was significantly increased by 22.4% （P＜0.05）. However, there was no significant effect on the related indicators of soil water storage performance in 10-30 cm soil layer （P＞0.05）. In conclusion, the water conservation function of litter layer and soil layer in Chinese fir forest was enhanced with the extension of thinning years.