Effects of thinning and stand types on litter stock and soil water-holding capacity

Objective  This study aims to explore the effects of thinning and stand types on forest litter stock and soil water-holding capacity, and to provide scientific basis for evaluating water conservation function of different forest stands. Method  Two forest types (Cunninghamia lanceolata forest and broad-leaved forest) and two types of thinning (thinning C. lanceolata forest and thinning broad-leaved forest) in three small river basins in Jiande City, Zhejiang Province were taken as the research objects. Litter and soil (0−10, 10−30, 30−60 cm) were collected in the field, and the water immersion method was used to analyze the influence of thinning on the forest litter stock and water-holding capacity of different forest stands. Three standard plots (20 m×20 m) were selected in each forest stand for litter collection and soil sampling. The litter stock, water-holding capacity and water absorption rate, as well as the soil bulk density, porosity and water-holding capacity were determined. The statistic data of litter and soil characteristics were analyzed using one-way ANOVA and Duncan. Result  The litter stock of thinning C. lanceolata forest decreased by 25.2% (P＜0.05), while the maximum water-holding rate and effective retention rate of litter increased by 24.4% and 47.1%, respectively (P＜0.05). Thinning had no significant effect on litter stock in broad-leaved forests, but the maximum water-holding capacity and effective retention capacity of litter increased by 42.5% and 42.2% (P＜0.05) respectively, compared with those without thinning. The overall water-holding capacity of litter in thinning forest was higher than that in normal forest. Thinning significantly increased non-capillary pores porosity and water-holding capacity of non-capillary pores in 10−60 cm soil layer of C. lanceolata forest (P＜0.05). Thinning significantly increased soil non-capillary pores porosity and non-capillary water-holding capacity in 30−60 cm soil layer, as well as those in 0−10 and 30−60 cm soil layer of broad-leaved forest (P＜0.05). The maximal water-holding capacity of each soil layer in the thinning C. lanceolata forest was significantly higher than that in the thinning broad-leaved forest, and the maximal water-holding capacity of 0−60 cm (3 775.19 t·hm−2) of the thinning C. lanceolata forest was higher than that of other forest stands. Conclusion  Thinning significantly improves the water-holding capacity of forest litter and soil, and the water conservation function of litter and soil in the thinning C. lanceolata forest is the strongest among the four treatments for two stands. [Ch, 3 fig. 5 tab. 24 ref.]