SOIL CHARACTERISTICS AND WATER HOLDING CAPACITY OF THREE TYPICAL SHRUBS IN THE SOUTHERN SLOPE OF QILIAN MOUNTAINS

摘要

In order to grasp the situation of soil properties and water storage capacity of three typical shrubs in the southern slope of Qilian Mountains, NW China, soil characteristics and water holding capacity under three typical shrubs (Potentilla fruticosa, Caragana jubata and mixture of these two) in the Southern Slope of Qilian Mountains were investigated in this project. Soil bulk density, porosity, moisture content and water holding capacity were studied based on both field survey and laboratory experiments. Results showed that: (1) with the increase of the depth, bulk density increases while the total porosity decreases in the three typical shrubs. (2) Soil bulk densities follow the high to low order that 0 to 50 cm soil layer is mixture shrub (1.19 g/cm~3), Caragana jubata (1.08 g/cm~3) and Potentilla fruticosa (0.95 g/cm~3). The order of the total porosity is Potentilla fruticosa (62.53 %), Caragana jubata (58.35 %) and mixture shrub (54.73 %). (3) In the soil layer of 0 to 50 cm, the soil saturation water storage capacity under Potentilla fruticosa, Caragana jubata and mixture shrub is 3126.74 t/hm~2, 2917.54 t/hm~2, 2736.71 t/hm~2, respectively. (4) The soil non-capillary water holding capacities of the three shrubs are 1788.08 t/hm~2, 1446.13 t/hm~2, 1164.12 t/hm~2, respectively. As a result, we suggest that in the region of the southern slope of Qilian Mountains, the soil under the Po- tentilla fruticosa has a better soil structure, followed by Caragana jubata, while mixture shrub had the poorest characteristics. Similarly, the soil under the Potentilla fruticosa has the better water holding capacity, which is followed by Caragana jubata in order, while mixture shrub has the weakest capacity.