NIE Zexu, QI Shi, MA Xiyao, LI Yue, WU Bingchen

（School of Soil and Water Conservation, Beijing Forestry University，Beijing 100083）

Abstract: In order to study effects of different stand densities of planted Platycladus orientalis on soil characteristics and water conservation capacity, fixed plot investigations and sampling analyses for seven levels of stand density were carried out in mountainous areas in the Huaying city, and water holding capacities of litters and physicochemical properties of soils were measured for calculating water storage capacities of forests. Variance and correlation analyses of stand densities were conducted in this study to explore the optimal stand retention density and to provide a basis for the sustainable management of local plantation. The results showed that the maximum water holding capacity of planted Platycladus orientalis litters increased and then became decreasing as the forest density increasing. The effective interception capacity varied significantly with the forest density, and the optimal interception capability was found at the medium density (3975 individuals/hm2). The stand density had significant effects on the fractal dimension, mean weight diameter and average geometric mean diameter of soil aggregates, as the stand density increasing, all of them showed a trend of increasing first and then decreasing. The organic matter contents of soil aggregates were affected by the stand density significantly, the highest organic matter content of soil aggregate was found at the stand density of 4250 individuals/hm2. The stand density also significantly affected the maximum water holding capacity and the capillary water holding capacity of soils, especially, the soil water holding capacity of shallow soil increased in the stand density range of from 675 individuals/hm2 to 5300 individuals /hm2. In summary, the litter in the planted Platycladus orientalis forest played the major role in the water conservation. The effective interception capacity varied with forest land densities in an order of 3975 individuals/hm2>1475 individuals/hm2> 4250 individuals/hm2>5775 individuals/hm2>5300individuals/hm2>2675 individuals/hm2>675 individuals/hm2, and the forest with medium stand density had the best ability in water conservation.

Keyword：planted Platycladus orientalis; soil characteristic; water conservation; stand density

EARTH AND ENVIRONMENT Vol.48, No.3, Tot No.335, 2020, Page 318-326