湟源山坡地梯田退耕还林还草效果研究初报

通过对湟源山坡地梯田退耕还林工程连续9年的定点观测调查,结果表明:在顶坡梯田,所栽植的榆树Ulmus pumila有94%死亡,沙棘Hippophae rhamnoides有19.4%死亡;在中坡梯田，榆树、沙棘的死亡率分别为93%、18.2%;在底坡梯田，榆树、沙棘的死亡率分别为92.7%、18.6%;而柠条Caragana korshinskii在3个坡位梯田中都100%的成活,但长势不旺,而以赖草Leymus secalinus为主的草本植物,通过9年的自然侵入生长,其生物量(干物质)达到850 g/m2以上。同时，对各坡位草本产量增长规律进行了分析论述，建立了3个坡位草本产量与生长年限回归方程，中坡：y=78.033+102.473 3x；底坡:y=67.333+102.253 3x；顶坡:y=54.244 4+101.92x；如实评估了坡地梯田退耕还草后的经济效益。

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.