Abstract:

Abstract： The ‘fertile islands’ is formed under integration of biological and nonbiological process and it is a phenomenon that soil nutrients are enriched around shrubs in arid and semiarid regions， and the soil nutrients decrease gradually from canopy center to canopy outside. This paper studied soil nutrient ‘fertile islands’ effective range and spatial variability of Tamarix shrubs in Fukang of north Xinjiang and the Tarim river of south Xinjiang with Geo\|statistics and GIS technology. The results indicated： Tamarix had a visible function to congregate nutrients，and the enrichment ratio of inside to outside of canopy was general over one. Once Tamarix had withered，this function was fading away. The enrichment ratio of north of Xinjiang was bigger than that of south of Xinjiang. However there was no significant diference in ‘fertile islands’ characteristic over the different growth stages of Trmarix. The ‘fertile islands’ effective range in Tamarix in Fukang was 3.9～14.8 m， while the ‘fertile islands’ effective range was 6.2～10.1 m in the Tarim river. The effective function range was all over canopy. In the research area，soil main nutrition presented intense spatial selfcorrelation，and the spatial variability was determined mostly by structural factors. A weak Aeolian enrichment and intensive desertification in arid area of Xinjiang weakened ‘fertile islands’ function by the deserted vegetation,
Tamarix.

Key words: Key words： Tamarix, &lsquo, fertile island&rsquo, soil nutrition, canopy, spatial variability