Vegetation Change and Soil Nutrient Distribution along an Oasis-Desert Transitional Zone in Northwestern China  

作　　者：Bao-Ming Chen Gen-Xuan Wang Dong-Liang Cheng Jian-Min Deng Shao-Lin Peng Fu-Bo An 

机构地区：[1]State Key Laboratory of Biocontrol, Zhongshan (Sun Yat-Sen) University, Guangzhou 510275, China [2]College of Life Sciences, Zhejiang University, Hangzhou 310027, China [3]Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, Lanzhou University, Lanzhou 730000, China [4]Gansu Desert Control Institute, Wuwei 733000, China

出　　处：《Journal of Integrative Plant Biology》2007年第11期1537-1547,共11页植物学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(90102015,30170161 and 30670385);Cooperation Project of International in China and Greece(05-46).

摘　　要：Many studies have focused on soil nutrient heterogeneity and islands of fertility in arid ecosystems. However, few have been conducted on an oasis-desert transitional zone where there is a vegetation pattern changing from shrubs to annual herbs. The goal of the present study was to understand vegetation and soil nutrient heterogenity along an oasis-desert transitional zone in northwestern China. Three replicated sampling belts were selected at 200 m intervals along the transitional zone. Twenty-one quadrats （10 x 10m） at 50m intervals were located along each sampling belt. The vegetation cover was estimated through the quadrats, where both the soil under the canopy and the open soil were sampled simultaneously. The dominated shrub was Haloxylon ammodendron in the areas close to the oasis and Nitraria tangutorum dominated the areas close to the desert. In general, along the transitional zone the vegetation cover decreased within 660 m, increased above 660 m and decreased again above 1 020 m （close to the desert）. The soil nutrients （organic matter, total N, NO3^- and NH4^＋） showed significant differences along the zone. The soil nutrients except the soil NH4^＋ under the canopy were higher than those in open soil, confirming ＂islands of fertility＂ or nutrient enrichment. Only a slight downward trend of the level of ＂islands of fertility＂ for soil organic matter appeared in the area within 900 m. Soil organic matter both under canopy and in interspace showed a positive correlation with the total vegetation cover, however, there was no significant correlation between the other soil nutrients and the total vegetation cover. We also analyzed the relationship between the shrubs and annuals and the soil nutrients along the zone. Similarly, there was no significant correlation between them, except soil organic matter with the annuals. The results implied that annual plants played an important role in soil nutrient enrichment in arid ecosystem.Many studies have focused on soil nutrient heterogeneity and islands of fertility in arid ecosystems. However, few have been conducted on an oasis-desert transitional zone where there is a vegetation pattern changing from shrubs to annual herbs. The goal of the present study was to understand vegetation and soil nutrient heterogenity along an oasis-desert transitional zone in northwestern China. Three replicated sampling belts were selected at 200 m intervals along the transitional zone. Twenty-one quadrats （10 x 10m） at 50m intervals were located along each sampling belt. The vegetation cover was estimated through the quadrats, where both the soil under the canopy and the open soil were sampled simultaneously. The dominated shrub was Haloxylon ammodendron in the areas close to the oasis and Nitraria tangutorum dominated the areas close to the desert. In general, along the transitional zone the vegetation cover decreased within 660 m, increased above 660 m and decreased again above 1 020 m （close to the desert）. The soil nutrients （organic matter, total N, NO3^- and NH4^＋） showed significant differences along the zone. The soil nutrients except the soil NH4^＋ under the canopy were higher than those in open soil, confirming ＂islands of fertility＂ or nutrient enrichment. Only a slight downward trend of the level of ＂islands of fertility＂ for soil organic matter appeared in the area within 900 m. Soil organic matter both under canopy and in interspace showed a positive correlation with the total vegetation cover, however, there was no significant correlation between the other soil nutrients and the total vegetation cover. We also analyzed the relationship between the shrubs and annuals and the soil nutrients along the zone. Similarly, there was no significant correlation between them, except soil organic matter with the annuals. The results implied that annual plants played an important role in soil nutrient enrichment in arid ecosystem.

关 键 词：China DESERT islands of fertility soil nutrient heterogeneity transitional zone. 

分 类 号：S15[农业科学—土壤学]