Relationship Of Heterogeneity And Non-biological Soil Factors In Soil Microbial Of Haloxylon Ammodendron From Minqin

At present, land desertification has become one of the most serious ecological problems in China. Planting artificial sand-fixation forest was one of the effective measures of controlling land desertification and rehabilitating ecological habitats. The aim of the paper is to explore the spatial variability of soil microorganism and the relationships between itself and soil factors(For instances.soil physical property, soil nutrients and others) of artificial forest in Gansu Minqin desertification land by analyzing the composition of soil microorganism, soil physical properties and soil nutrient changes in the different artificial Haloxylon ammodendron forest vegetation on the basis of the method of spatial sequence instead of time successive sequence. Finally, we provided some scientific evidences for environment construction and ecological restoration in the west of China. The results were showed that :1) After planted H ammodendron forest, plant species diversity was gradually increased and restored the vegetation and ecological environment. the community succession was ranked from primarily the single H ammodendron shrub community to H ammodendron community(the dominant annual herbage with the artificial shrub).2) The number of soil bacteria, fungi, actinomycetes and the content of microbial carbon firstly increased and then decreased slowly and these value reached the maximum after only 30 years afforestation.3) The soil particle composition in the artificial sand fixation forest with various ages had a significant difference(P < 0.05). The phenomenon of soil formation was obvious. The soil moisture content and p H value in the five different age sample areas indicated the obvious stripe features. In addition, the shorter the distance from the trunk, the higher the soil p H values and the moisture, viscosity and silt contents, the smaller the sand content.4) On the basis of largely regression analysis of the soil organic carbon, nitrogen and phosphorus contents. the data indicated that the total levels of the soil organic carbon and nitrogen phosphorus at soil surface were obviously higher than the values at middle and lower soil. and these values increased with the increase of the forest ages. From a horizontal direction, the organic carbon and total phosphorus content of the soil near the trunk were significantly lower than those values beneath the canopy. and the total nitrogen, available phosphorus and nitrogen showed the clear effects of age class,5) Factor analysis showed that the values all the soil factors were increased with the growth of the(H. ammodendron) artificial forest ages. Horizontally, the nutrient contents within the area of 0~50 cm near the trunk accounted for 69.95% the contents within the area of 0~150 cm near the trunk. Vertically, the soil nutrient contents with the range of 0~5 cm near soil surface were the highest and had a negative effect between soil nutrient contents and soil layers.6)There was a positive significant correlation(P) between the three soil microbes and microbial biomass carbon, soil p H, organic carbon, total nitrogen, moisture content, clay and silt content, and a negative correlation(P) between the soil sand content, carbon and nitrogen ratio. The correlation between the total soil phosphorus, available phosphorus, available nitrogen, nitrate nitrogen and ammonia nitrogen was insignificant(P).