Hydrological effects of litter of Betula platyphylla forest with different densities in alpine region, Qinghai of northwestern China

ObjectiveIn order to quantitatively study the hydrological effects of different densities of Betula platyphylla in Qinghai alpine region and to provide theoretical basis for the afforestation, allocation and management of the hydrological effects of local Betula platyphylla forest.

MethodThe investigation was carried out in July and August of 2016 in Baoku Forest Area of Datong County, Qinghai Province of northwestern China. Three Betula platyphylla plots were selected for each density, and the stand age was 22-24 years. The litter thickness, storage, maximum water-holding rate and other indexes of five different densities of Betula platyphylla forest were measured. The relationship between the water-holding capacity of litter and soaking time, the relationship between water absorption rate and soaking time were studied by soaking method.

ResultThere were significant differences in the litter thickness, storage and water-holding capacity among the five kinds of stand density. (1) As to the 5 density stand ordered as 225, 500, 688, 900, 1 220 tree/ha, the litter thickness was 4.51, 4.64, 5.30, 6.10 and 5.35 cm, respectively; the litter storage was 11.22, 13.54, 15.33, 17.86 and 15.86 t/ha. The maximum water-holding rate of litter was 227.91%, 214.40%, 215.44%, 236.81% and 221.70%, respectively. (2) The maximum water-holding capacity and the effective water-interception capacity of litter were both in the order of 900 tree/ha>1 220 tree/ha>688 tree/ha>500 tree/ha>225 tree/ha, respectively. (3) The relationship between the water-holding capacity and soaking time of litter was fitted well with the logarithmic function and the regression coefficient R² was over 0.90. The relationship between water absorption rate and soaking time had the power function and the regression coefficient R² was over 0.99.

ConclusionThe litter storage, maximum water-holding capacity and effective water-interception capacity reached the maximum at the stand density of 900 tree/ha. The effects of water conservation on litter were optimal in the stand with density of 900 tree/ha. Therefore, from the perspective of the hydrological effect of litter, the density was 900 tree/ha, and the hydrological effect of litter is the best.