The Characteristics Of "Fertile Island" Of Haloxylon Ammodendron In The North Of Xinjiang

The desertification is the global significant environment problem, and in China, the desertification area of Xinjiang is the biggest. Under the arid wilderness severe habitat, the haloxylon ammodendron is distributing abroad, and in order to use the limited nutrients to continue its lives, inevitably forms"fertile island". The characteristic of"fertile island"is a mirror that we understand the wilderness ecosystem stability and intrinsic evolution rule, so studies on the characteristic of"fertile island"about haloxylon ammodendron has the extremely important necessity and the practical significance. This study used Geostatistics combined with GIS, studied on characteristic of"fertile island"about the north of Xinjiang haloxylon ammodendron. The results indicated that:Compared the content of root soil element with canopy edge and bare area, it had remarkable difference, nevertheless the difference of canopy and bare area were not remarkable for bigger and smaller haloxylon ammodendron, and the content presented that the root>the edge of canopy>bare area. This showed that the root of haloxylon ammodendron had strongly"fertile island", although the sear haloxylon ammodendron had weakly. The content of root soil nutrient element presented that the bigger haloxylon ammodendron> the medium haloxylon ammodendron> the smaller haloxylon ammodendron.In every growth stages of haloxylon ammodendron, the content difference of soil Mg²⁺ were not remarkable at the root, the edge of canopy and at the bare area. Compared the content of root soil Na⁺, Cl^- with canopy edge and bare area for the bigger, the smaller and the sear haloxylon ammodendronthe, it had remarkable difference, and presented the"salinity island". The soil salt and pH of haloxylon ammodendronthe root was not reduce, and displayed that the root>the edge of canopy>bare area. The canopy, height and diameter of haloxylon ammodendron impacted on the soil nutrient enrichment of the root, but not impacted on the enrichment of canopy edge; impacted on the soil SO₄^2-, Cl^-, tatal alkalinity and total salt enrichment of the root, but not impacted on the enrichment of soil Ca²⁺, Mg²⁺, K⁺, Na+, pH; impacted on the soil Mg2+, Cl- enrichment of the canopy edge, but not impacted on the other salinity ions. At the haloxylon ammodendron root, the effects of"fertile island"and"salinity island"were stronger than canopy edge.At the research area, the variance coefficient of soil total alkalinity was highest, the soil total salt, organic matter, available N, available K and available P belonged to the medium variation, and the soil pH were relatively stable, and belonged to the weak variation. The soil had the alkalize characteristic, and the decisive factors were terrain, texture and precipitation, so before the haloxylon ammodendron settled down, the soil had the alkalize characteristic, and the haloxylon ammodendron was alkali-resistant plant, but if the total alkalinity excessively high, the haloxylon ammodendron also grew difficulty.At the center of haloxylon ammodendron, the content of soil element was higher than other regions, and displayed"fertile island"and"salinity island". The effect areas of haloxylon ammodendron within canopy, and at the south of haloxylon ammodendron appeared other island structure, it impossible related to the direction of wind.