Research On Sand Fixing Vegetation Restoration And Reconstruction

Vegetation in half fixed dunes outside the oasis plays important role in decreasing damage of sand and protecting oasis, which is one of the main objects in sand fixing vegetation restoration and reconstruction researching. In addition, the conclusion of artificial sand fixing vegetation researching missing long period investigation and analysis is doubtful.The paper analyses the natural Ammopiptanthus mongolicus communities, Nitraria tangutorum Communities and Artemisia Ordosica Communities in the half fixed dunes outside the oases irrigated by Huanghe River and well water respectively (hfdoiHR & hfdoiww) and the artificial vegetation planted two decades ago on the north east of Ulanbuhe desert. Belt (transect) composed of contiguous (abutting) quadrats is used in sampling, in which the cover of each species is estimated. Due to aiming at the multi-species pattern of shrub and grass, grass species is mainly considered in deciding the size of quadrat and the shrub species' needs are meet by lengthening the belt (transects). Making use of the methods of multi-scale ordination modified by Ver Hoef & Glenn-Lewin (1989), the pattern intense and pattern consistency index and the contribution of species to pattern Dale & Zbigniewicz (1995) put forward, and the moving weight average quadrat scores (Noy-Meir & Anderson) etc., the paper contrasts the vegetation pattern characters in half fixed dunes outside the Huanghe River irrigating oasis and the well water irrigating oasis, analyses the relation between vegetation and sand height and the structure of artificial vegetation after two decades of succession. The purpose of the paper is to provide the base data for sand fixing vegetation restoration and reconstruction in the area. The results show that:(1) Most patterns of the two Ammopiptanthus mongolicus communities in hfdoiHR & hfdoiww are multi-species shrub patterns and the contribution of grass species to pattern isvery low. The patterns of Ammopiptanthus mongolicus communities in hfdoiHR are mainly shrub patterns controlled by Artemisia Ordosica and Ammopiptanthus mongolicus, besides some shrub patterns controlled by Ammopiptanthus mongolicus, Nitraria tangutorum, Artemisia Ordosica and Artemisia sphaerocephala. The patterns of Ammopiptanthus mongolicus communities in hfdoiww are shrub pattern controlled by Nitraria tangutorum and Ammopiptanthus mongolicus. The pattern scale of Ammopiptanthus mongolicus communities in hfdoiHR is much smaller, the pattern intense is larger and the pattern consistency index is lower, contrasting with that in hfdoiww.(2) The patterns of the two Nitraria tangutorum communities in hfdoiHR & hfdoiww are all shrub patterns controlled by single species Nitraria tangutorum. The number of pattern scale is more, pattern scale is larger, the corresponding pattern intense and the pattern consistency are lower in Nitraria tangutorum communities in hfdoiHR , contrasting with that in hfdoiww.(3) The patterns of the Artemisia Ordosica communities in hfdoiHR are shrub patterns controlled by single species Artemisia Ordosica and the multi-species shrub patterns controlled by Artemisia sphaerocephala, Nitraria tangutorum and Artemisia Ordosica. The patterns of the Artemisia Ordosica communities in hfdoiww are shrub patterns controlled by single species Ammopiptanthus mongolicus and the multi-species shrub pattern controlled by Artemisia Ordosica and Nitraria tangutorum. The number of pattern scale is less, the average pattern intense is higher, and the total consistency index of the whole community is lower in Artemisia Ordosica communitie in hfdoiHR, contrasting with that in hfdoiww.(4) The relation of vegetation and sand height is showed by that of moving average of weighted quadrat score and sand height that not only emphasize that of the species combination and sand height but also that of the individual species and sand height. The Ammopiptanthus mongolicus community in hfdoiww shows some negative correlation, the Nitraria tangutorum Community in hfdoiww shows no correlation; and Most of the vegeta...