GIS支持下的农业土地资源评价研究—以贵阳市区为例

本文基于土地质量评价的“压力－状态－响应”（PSR）模型，选取土壤重金属污染作为评价的一个压力为指标，应用GIS对贵阳市区农业土地资源进行了综合质量评价。定量评价的结果表明，区域农业土地资源中大部分土地资源重较好，但旱地和水田共有17．11km^2的重金属重度污染区，这部分耕地已不适宜种植农作物，同时，适合人类耕作的高质量耕地由于土壤重金属污染减少了近1／3，说明贵阳市区进行土壤重金属污染防治具有重要的意义。     

A Comparative Study on the Microbiological Characteristics of Soils Under Different Land—Use Conditions from Karst Areas of Southwest China

Microbiological and physical-chemical characteristics of subtropical forest,grassland and cropfield soils from the karst areas of Southwest China were investigated.The study revealed that the conversion of natural forest to other forms of land would lead to a reduction in soil organic C(26.2%-35.3%),total N(37.2%-55.8%),totalP(32.9%-43.6%),microbial biomass C(35.4%-49.1%),N(37.2%-55.8),and P(25.8%-41.9%).Comparative analysis of microbial activity in terms of basal soil respiration showed maximum activity in forest soil and minimum in cropfield soil.Analysis of microbial metabolic respiratory activity indicated a relatively greater respiratory loss of CO2-C per unit microbial biomass in cropfield and grassland than in forest soil.Considering the importance of microbial components in soil,it is concluded that land use in different ways will lead to the reduction of biological stabilty of soil.