黄土高原不同退耕还林地森林植被改良土壤特性研究

Study on Improving Soil Properties of Forest Vegetation in Different Land Where Returning Farmland to Forests in Loess Plateau

对比研究了青海省大通县不同类型退耕还林地、草地、农田的土壤性质，包括土壤容重、土壤孔隙度、土壤水稳性团粒结构、土壤饱和导水率。结果表明：华北落叶松容重最小，为农田容重的62％，青杨青海云杉混交林是农田土壤容重的83％；0～15cm土层青海云杉混交林〉0．25mm的团粒结构含量为45．21％，草坡、耕地分别为32．18％、20．81％；北落叶松纯林的最小饱和导水率是1.22mm／min，林地中饱和导水率最小的是落叶松青海云杉混交林，为0．17mm／min，草地和农田分别为0．11mm／min、0．09mm／min。退耕还林后，与农田相比，林地土壤物理性质得到明显改善,针阔混交林改良土壤特性作用较好。除了华北落叶松纯林和华北落叶松青海云杉混交林外，针阔混交林的土壤物理性质好于阔叶纯林和针叶纯林，草坡和农田较差，草坡略好于农田。

The soil characteristics of different land where returning farmland to forests,grass land and farmland were contrasted and researched, including soil bulk density, soil porosity, soil water stable aggregate structure and soil saturated hydraulic conductivity in Datong county of Qinghai province. The results showed that for the soil bulk density,the least is Larix principis- rupprechtii,occupying 62% of that in farmland,while P. cathayana and Picea crassifolia mixed plantation occupied 83%; For Picea crassifolia mixed plantation,the content of aggregate structure which is lager than 0.25 mm is 45.21% in the soil layer from 0 to 15cm,for grass slope and cultivated land it is respectively 32.18% and 20.81% the minimum saturated hydraulic conductivity of the north Larix gmelini pure plantation is 1.22 mm/min,the saturated hydraulic conductivity of Larix principis-rupprechtll and Picea crassifolia mixed plantation is 0.17 mm/min which is the least in the forest land, grass land and farmland is respectively 0.11 mm/min and 0.09 mm/min. Compared with farmland,the soil physical characteristics of forest land have greatly improved after returning farmland to forest,the effect of coniferous and broad-leaved mixed plantation on soil amelioration is better than others, except Larix principis- rupprechtii pure plantation and Larix principis-rupprechtii and Picea crassifolia mixed plantation,the soil physical characteristics of coniferous and broad-leaved mixed plantation is better than that of coniferous pure plantation and broad-leaved pure plantation,both grass slope and farmland are not good, but grass slope is slightly better than farmland.