运用仙农熵指数的方法，对1995年、2005年和2010年西安市土壤和土地利用的组成和空间分布多样性及其关联性进行了研究。结果表明：随着海拔高度的升高，成土因素趋向复杂，土壤组成多样性逐渐降低；西安市土壤构成组分相对均匀，多样性指数为0.78，1995—2005年和2005—2010年两个时间段土地利用混乱程度提高不明显，构成多样性指数分别增加0.011和0.008；研究区51个土属中6个土属多样性指数在0.65以上，面积最大、多样性指数(0.793)最高的为麻骨石棕壤性土，最低的为黄绵土，仅为0.023；6种土地利用类型中除未利用地外多样性指数均高于0.7，其中农用地最高，达到0.927，由1995—2010年，农用地面积减少了185.119 km²，建设用地增加193.677 km²，并且近5年的变化率明显更快，但多样性指数均小幅度降低；与油土和黄墡土公共面积最大的两种土地利用类型是农用地和城镇建筑用地，同时二者之间的关联度系数也都在0.8以上。因此，以仙农熵来评估西安市土壤和土地利用的多样性是可行的，且1995—2010年间西安市城市的扩展对于主要的农业土壤占用量不大，未出现重要土壤类型受到威胁的情况，但对油土的占用应引起重视。

The diversities of the composition and spatial distribution of soil types and land use types in Xi’ an City and their correlation in 1995, 2005 and 2010 were analyzed by using the modified Shannon entropy formulate respectively. The results showed that with the increase of altitude, the soil forming factors tended to be complex and the diversity of soil composition decreased gradually. Soil distribution was relatively homogeneous with the composition diversity index of 0.78. Land use chaos were increased inconspicuously with a bit increment of the diversity index of soil composition by 0.011 and 0.008 during 1995—2005 and 2009—2010, respectively. Only 6 of 51 soil types had the spatial diversity higher than 0.65, rocky brown soil had the largest area and highest spatial diversity index (0.793), but loessal soil had the lowest spatial diversity index (0.023). The diversity indexes of all the land use types were higher than 0.7 except the unused land, in which farmland had the highest spatial diversity index (0.927). From 1995 to 2010, the area of farmland decreased by 185.119 km² but construction land increased by 193.677 km², and they changed more rapidly from 2005 to 2010, meanwhile, their diversity indexes slightly decreased. The oil soil and loessal soil had largest areas in farmland and construction land, and all correlation coefficients between the two soils were higher than 0.8. The above results prove that Shannon entropy is an effective in estimating soil diversity, and the expansion of Xi’an City from 1995 to 2010 only occupied little cultivated soil, indicating the important soil types are secure at present, but more attentions should be paid to gradually enlarged occupation of oil soil.

S155

国家科技基础性工作专项项目(2014FY110200A08)资助。