natural grazing ground 天然牧场
desertification 土地沙化
acidification 土地酸化
soil alkalinization 土壤碱化
soil erosion 土壤侵蚀
grain for green; return cultivated land to forestry or pasture 退耕还林还草
restore the reclaimed land to forest 退田还林
hazardous wastes 危险废物
greenhouse gases 温室气体
pollution index 污染指数