Revegetation is one of effective ways to reduce the impacts of desertification. Caragana microphylla Lam. and Pinus sylvestris var. mongolica Litrin have been widely used to stabilize shifting sand in Horqin sandy land since 1980′s. However, soil water deterioration has been a major concern in C. microphylla and P. mongolica plantations, and in many places current soil moisture can′t meet the demand for plants′ growth. To determine water budget of the C. microphylla and P. mongolica plantations, we studied the effect of plantations on soil moisture, and assessed the evapotranspiration in C. microphylla and P. mongolica plantations.
Investigation was conducted at a fenced plot at Wulanaodu (119°30′E and 42°29′N, 479m a. s. l), situated at the west edge of the Horqin sandy land in Inner Mongolia, North China. Plants of C. microphylla grown for 5 years and P. mongolica grown for 7 years in the plantations were selected, and transplanted to iron boxes (400cm×200cm×120cm) which can drain extra water. A plant density 1m×1m was applied to P. mongolica, and two plant densities 1m×1m and 1m×2m were applied to C. microphylla. The transplanted plants grew for two years in the boxes. Soil moisture from soil surface to depth 80cm were measured at 20cm intervals in boxes every 10 days (2004) or 3 days (2005) during the growing seasons with TDR water menstruation apparatus. The evapotranspiration was estimated according to a mathematical model, and the characteristics of soil water consumption and evapotranspiriation of these two plantations were analyzed.
The soil water of P. mongolica was more than that of C. microphylla when the density (1m×1m) was same. The soil water of C. microphylla with 1m×2m density was more than that of 1m×1m density. The evapotranspiriation ranging from the high to the low was C. microphylla.(1m×1m), C.microphylla( 1m×2m) and P. mongolica (1m×1m) during the growing seasons. The evapotranspiration of individual plant ranging from the high to the low was C. microphylla (1m×2m), C.microphylla.(1m×1m), and P. mongolica (1m×1m) during the growing seasons. C. microphylla grown for 5a consumed more water than P. mongolica grown for 7a when the density was same.