Study On Fertile Islands Features Of Biological Soil Crusts In Kubuqi Desert

In the world,ecological researchers very attached importance to the ecological roles of the biological soil crusts in sandy environment,because it could effect soil particle stability and erosion,atmospheric nitrogen-fixing,plants assimilate nutrients,soil-plant-water relations,water infiltration in soil,seed germination and plants establishment and cover,etc.In this paper, We made a systematic study on"fertile islands effection"and its formation mechanism of biological crusts in Kubuqi desert and Maowusu sandland, from the sides of the biological soil crusts soil fertile, crusts soil biochemistry features, particle matter and ecological effections of the biological crusts, etc.The results showed that the biological crusts in desert areas had not only the evident"fertility island"phenomenon,but also the nutrients content of biological crusts were signifiance difference in difference kinds of biological crusts. Compared with the control sand soil, available nitrogen content of biological crusts was increased 95.07%, available phosphate content was increased 36.43%, available potassium content was increased 18.37%, total nitrogen content was increased 77.83%, total phosphate content was increased 19.91%, organic matter content was increased 55.35%, respectively. Bacteria content in biological crusts was increased 2179.27 times, compared with the control sand soil, microfungi content was increased 13.99times, actinomyces content was increased 3.04times, respectively. The content of humus composition in biological crust were higher than control sand soil. Humic content was increased 80.1%, compared with the control sand soil, humo-acid content was increased 83.7%, fulvic-acid content was increased 63.4%,rate of humo-acid content and fulvic-acid content(H/F) was increased 19.7%, respectively.Peroxyhydrogenase enzyme active of biological crusts was increased 2.5times, compared with the control sand soil,urease active was increased 0.54times, invertase active was increased 16.17times, polyphenol oxidase active was increased 1.95times, respectively.Compared with the control sand soil,physical features of biological crusts were obvious improve.0.1-0.15mm particle matter content was 42.7%,but 0.05-0.2mm particle matter content was 84.83%,and physical clay(<0.01mm)content in biological soil crusts was increased 87.8%, clay content was increased 59.1%, respectively.This showed that fine soil grain in biological soil crusts had obvious increased tendency. The maximum moisture capacity was increased 141.5% in biological crusts layer, compared with the sand of no bio-crust layer,the capillary capacity was increased 96.0% ,the capillary porosity was increased 37.2%,soil total porosity was increased 68.9%, respectively.This showed that capacity of water-holding in biological soil crusts were obvious improve,and effected precipitation permeate or water second distribute process.The study results of"fertile islands"formation mechanism in biological crusts showed that biological crusts layer cover could increased nutrients content for below sand soil through precipitation permeate washing,and it promoted plants assimilate more nutriment.The matter import ways of biological soil crusts fertility island had many ways,including the effection of living macrobiotics metabolism in crusts levels,wind-sand flow of near surface,dust deposition and plants decomposition course,etc.Source of particle matter in biological soil crusts was wind-sand flow of near surface,and not dust deposition.Biological crusts layer cover had preserved effection for nature water content in 0-5cm soil layer,compared with the sand of no biological crusts layer,effecting precipitation permeate,and could not obvious restrained from the water evaporate process indoor experiment.The study results showed that artificial inoculate technology could formation biological soil crusts layer in flow sand dune,and bring abut the goal for sand-control in short time.