Characteristics of soil water consumption of typical shrubs () and trees () in the Horqin Sandy Land area, China

Abstract

Reforestation is one of the most effective ways to reduce the impacts of desertification. Caragana microphylla Lam. and Pinus sylvestris var. mongolica Litrin have been widely used to stabilize shifting sands in the Horqin sandy land area since the 1980s. However, soil water depletion has been of major concern in C. microphylla and P. ongolica plantations and in many places current soil moisture cannot meet the demand of growing plants. To determine the water budget of C. microphylla and P. mongolica plantations, we studied the effect of plantations on soil moisture and assessed the evapotranspiration in plantations of both species. Investigations were conducted at a fenced plot at Wulanaodu (42°29′N, 119°30′E, 479?m a. s. l), located at the western edge of the Horqin Sandy Land area in Inner Mongolia, northern China. Five year old C. microphylla and seven year old P. mongolica plants were selected from the plantations and transplanted to iron boxes (400?cm×200?cm×120?cm) which can drain extra water. Plant spacing of 1?m×1?m was applied to P. mongolica, and two plant spacings of 1?m×1?m and 1?m×2?m to C. microphylla. The transplanted plants grew for two years in the boxes. Soil moisture from soil surface to a depth 80?cm were measured at 20?cm intervals in boxes every 10?d (2004) or 3?d (2005) during the growing season with a TDR water meter. The evapotranspiration was estimated from a mathematical formula and the characteristics of soil water consumption and evapotranspiration of these two plantations were analyzed. The soil water of P. mongolica was more than that of C. microphylla at the same 1?m×1?m spacing. The soil water of C. microphylla with the 1?m×2?m spacing was more than that of the 1?m×1?m spacing. The evapotranspiration ranged from high to low as follows: C. microphylla (1?m×1?m), C. microphylla (1?m×2?m) and P. mongolica (1?m×1?m) during the growing seasons. The evapotranspiration of individual plants ranging from high to low was C. microphylla (1?m×2?m), C. microphylla (1?m×1?m), and P. mongolica (1?m×1?m) during the growing season. C. microphylla grown for five year consumed more water than P. mongolica grown for seven years at the same spacing.

Key words： Horqin Sandy Land area; Caragana microphylla Lam.; Pinus sylvestris var. mongolica Litrin; soil water storage; evapotranspiriation