一、试验区自然概况:试验地设在80里河上游官心塘。地理座标北纬25°40′、东经116°25′,海拔高320m,地势较为平坦,土壤属花岗岩风化红壤,表土冲光,部分基岩裸露。原有植被为稀疏矮小的马尾松,每亩密度100～200株,平均高0.8m,树 First, the natural overview of the pilot area: Experimental site located in the upper reaches of 80 River heart Guan Tong. The geographical coordinates are 25 ° 40 ’north latitude, 116 ° 25’ east longitude and 320m above sea level. The terrain is relatively flat. The soil is red earth weathered by granite. The topsoil is reddish and part of bedrock is exposed. The original vegetation is sparsely short Pinus massoniana, density of 100 to 200 per acre, with an average height of 0.8m, trees