Influence Of Biological Soil Crusts On Spatial And Temporal Heterogeneity Of Soil Fertility In Kubuqi Desert, Inner Mongolia, China

The type, distribution, characteristics of soil fertility including physical and chemical properties of soil, soil nutrients, soil microbial biomass C and N, soil enzyme activity of biological soil crusts in moving dunes, semi-fixed dunes, fixed dunes and biological soil crusts formed artificially at different times in Kubuqi desert in Inner Mongolia of China was investigated and the temporal and spatial variation and the correlation among the indexes of the soil fertility were analyzed in this study. The results are as following:(1)The soil bulk density was decreased with the increase of the degree of sand fixation, which was in the pattern like L> BZ> GZ> GX for the surface of the soil and the similar trend was observed for the every soil layer under the surface. While, the soil bulk density was increased with the increase of the depth of the soil. The water content of soil in the 0-2cm layer was greatly influenced by the crust type and its presence, which was in the pattern like moss crust> algal crust> bare sand. In bare sand it was showed the growing trend from top to bottom, and water changes covered biological soil crust in the profile was shown the volatility increase, and in 2-5cm it was less than crust water content.(2) the. levels and spatial variation characteriz of soil nutrients(except for total K)influenced by biological soil crust were clearly stated in the pattaern like moss crust>algal crast> no cmst>bare sand, and the diverseness were significant (p<0.05) or highly significant (p<0.01); soil nutrients contents were showed a decreasing trend from the surface to the lower layer in the soil vertical profiles structure. It full illustrated the cumulative effects of soil nutrients with biological crust years.(3)In the differentiation of the season, MB and soil different enzyme activity were shown a significant or very significant seasonal variations. The levels and spatial variation characteriz of MB content was showed the regularity of significantly increasing trend with sandy fixed degree. The vertical differentiation characterized was showed a decreasing trend from surface to depth, the accumulation of soil MBC, MBN content were significantly affected by the type of biological crust, was showed that the biological cmst on the soil MBC, MBN and soil different enzyme activity content also had a cumulative effect, and which was showed increasing trend with the their development.(4)Correlation analysis showed:There was relevance between soil water and soil bulk density, and there was negative relevance with pH^ nutrients^ MBC, MBN> enzyme activity but no significant. In the desert ecosystem soil water visiblely was seen as an important factor of the role of effecting soil fertility, in addition to relevance with soil total P^ K> urease-. protease, there was negative relevance pH with Others; there were Significant or Very significant relevance among soil nutrients/except total MBC, MBN and soil enzyme activity. There was the more relevance between MBN(compared with MBC) with soil organic matter,toyal N,available K. MBN was more affected by the other indexes of soil fertility. There was very significant relevance between soil enzyme activity with MBC and MBN.