The applicable density of sand-fixing shrub plantation in Horqin Sand Land of Northeastern China

摘要

Caragana microphylla is the dominant perennial shrubs and widely used to stabilize shifting sand dunes in semi-arid, north China. To confirm the influence of plantations on soil water condition, we determined the soil moisture and evapotranspiration under different densities of sand-fixing C. microphylla shrubs during growth period. Result showed that the soil moisture under shrubs continued decreasing with the increasing of plantations densities. Soil moisture under 0.5 m x 1 m and 1 m x 2 m densities of C microphylla shrubs are under wilting humidity (1.55%) level, however, soil moisture under 2 m x 2 m densities and savageness C microphylla shrubs always keep above 1.6% during growth season. Evapotranspiration of all shrubs are low than rainfall and occupied above 90.3-98.5% of rainfall during growth phases, and continually increased with the increasing plant densities. The 0.5 m x 1 m density shrubs have the highest evapotranspiration, about to 298.3 mm (2009)/235.7 mm (2008) and occupied above 98.5% (2009)/94.4% (2008) of rainfall at the same time. The 2 m x 2 m density shrubs have the lowest evapotranspiration, about 283.4 mm (2009)/230.7 mm (2008), and soil moisture surplus 20.8 mm (2009)/19.0 mm (2008) at the end of growth season. According to soil moisture and evapotranspiration, the 2 m x 2 m of C microphylla shrubs is applicable density in Horqin sandy land, north-east of China.