Effects Of Salix Psammophila Checkerboard Sand Barrier To The Soil Seed Banks In Kubuqi Desert

Salix psammophila checkerboard sand barrier is the main measure for combating shiftsand dune and vegetation recovery. Both specification and period are important factors ininfluencing the role’s play of checkerboard sand barrier. The checkerboard sand barrier ofdifferent specification and period was studied, with mobile dune as the control. According tothe concept of space as a substitute for time and of the field investigation and indoorgermination test combined, we studied the species composition, density, biodiversity,similarity coefficient, spatial distribution pattern, season reserves change and the relationshipbetween soil seed bank and aboveground vegetation, wind velocity, erosion and sedimentationstatus in order to reveal the mechanism and action of soil seed bank. The result shows that:(1) The sand dunes with the same specification and different periods sand barriers haddifferent composition and density of soil seed bank. To some extent, the longer the period ofthe soil seed bank was, the composition and density of soil seed bank was bigger. Density ofthe upper part of the leeward slope was the least, and both the lower part of windward slopeand leeward slope of that was the biggest. The space distribution of soil seed bank in salixsand barrier was consistent, which appeared3less and2more area. The sand dunes withdifferent specifications and the same period had different composition and density of soil seedbank. In a certain extent, the number of species and density decrease as the specificationincrease; In the salix sand barrier checkerboard, the density presented appeared2less and2more area, of which the locations differ in each distribution area.(2) There were significant differences between the space and time patten with the differentperiods sand barriers. In vertical space distribution, the density of soil seed bank of mobiledune changed unconspicuously with soil depth, while sand dunes with different periodsdecreaded obviously as the soil depth increased, and the decreasing trend tended to be moreobvious as the period. In increased temporal distribution, density of soil seed bank of mobiledune changed unconspicuously with season, while density of soil seed bank of dunes withquadrate salix sand barrier changed obviously with season.(3) In the sand dunes with different specifications and different periods barriers, indexs asMargalet, Shannon-Wiener, ecological dominance and ecological dominance have the samechange trend. For the sand dunes with different periods, indexs presented the order of thedune with checkerboard sand barrier as7a＞the dune of2a＞mobile dune; and for the sand dunes with different specifications, indexs presented the order of the dune with checkerboardsand barrier as1.5m×1.5m＞the dune of4m×4m＞mobile dune. Indexs of mobile dune were0, and the indexs of each parts in the dune with checkerboard sand barrier of7a and2a hadthe same variation trend, which of the top part was biggest and the lower part of windwardslope least. For the salix sand barrier checkerboard indexs of each point locations along andperpendicular to the wind direction had the same variation trend, with the order as thenorthwest corner of the sand barrier(A)＞the midpoint of the north border inside the sandbarrier(F)＞the point a quarter of the diagonal to the northwest corner(B)＞the southeastcorner of the sand barrier(E)＞the point a quarter of the diagonal to the southeast corner(D)＞the midpoint of the south border inside the sand barrier(G)＞the midpoint of the diagonal(C).(4) Similarity coefficient of soil seed bank of the sand dunes with different specifications ordifferent periods barriers was different. For the dunes with different periods barriers,similarity coefficient of adjacent parts was medium similar or very similar; while similaritycoefficient of interval parts was less, and the farther the range was, the smaller the similaritycoefficient was; The longer the period of the soil seed bank was, the bigger the similaritycoefficient of each parts was; Under the same period, the smaller the specifications was, thebigger the similarity coefficient of each point locations was.(5) The similarity coefficient between soil seed bank and aboveground vegetation of the sanddunes with different periods barriers presented the order of the dune with checkerboard salixsand barrier as7a＞the dune of2a＞mobile dune; The number of aboveground vegetationaffected the density of soil seed bank, with the regular pattern that the more the abovegroundvegetation was, the bigger the density of soil seed bank was.(6) Wind speed, corrosion product status and the number of aboveground vegetation work onsoil seed bank jointly. The less the wind speed and the weaker corrosion product status andthe more aboveground vegetation was, the lager the density of soil seed bank was, and viceversa.