Preliminary study on ecological effect of converting cropping land to forestry or grassland at Beijishan terraces in Huang Yuan

Nine years of investigation of converting cropping land to forestry or grassland engineering at Beijishan terraces in Huang Yuan indicated that in terraced fields on top of the mountain, 94% Ulmus pumila and 19.4% Hippophae rhamnoides died; at the waist of the mountain, 93% U.pumila and 18.2% H. rhamnoides died; while at the bottom of the mountain, the death rates for two species reduced to 92.7% and 18.6%, respectively. 100% Caragana korshinskii survived at three levels with poor vigor; Grass dominated by L.secalinus reached 850 g/m2 dry matter. According to the grass growth regulation, three regression equations for the top, waist and bottom of the mountain were y=78.033+102.473 3x, y=67.333+102.253 3x, y=54.244 4+101.92x, respectively.