Basic Studies On Desertification Process And Vegetation Restoration Of Otindag Sandy Land--A Case Of Zhenglan Banner

Vegetation restoration is key for protecting desertification and weakening sandstorm harm. A series of this thesis contents are discussed in Otindag Sandy Land, such as desertification process, vegetation succession, adaptability, stability, dynamics of soil moisture and water consumption character of natural community, mechanism & channel of vegetation restoration. The results are showed as follow:(1) On the soil-plant-air continuity system, the relation of water-using mechanism & dynamics and sustaining development of plant community is clear. Reasons are shown that the artificial disturbance including over-reclamation, over-grazing and over-cutting for desertification and vegetation degeneration, whereas protecting natural vegetation and establishing artificial vegetation are main methods to make desert shrink and to promote vegetation restoration. The plants' progressive succession is beneficial for improving sandy land vegetation environment. Soil seed bank and the mechanism of seed germination are basic for the natural vegetation restoration in the research area.(2) The differences of the root systems distribution range and morphological anatomy structure and physiological index of the sandy dominant plants make differences of water-using mechanics and the adaptable mechanism in arid environment.(3) The temporal and spatial distribution pattern of soil moisture is different in plant communities of the research area. From up to down , the spatial distribution of soil water content can be divided into low value layer, severe fluctuation layer and relative stable layer . According to seasonal change of soil moisture, it can be divided into stable period (May-June), consumptive period (June-September) and slow restorable period (September-October). The distribution of dry and wet season of the soil is different with dry and wet season of weather. Soil water movement is mainly influenced by vegetation and precipitation.(4) Daily and seasonal variations of dominant plant species transpiration rate are distinct in the research area, and the transpiration rate is lineally relevant to environmental factors. The evapotranspirations of plant species are different in sandy plant communities of the research area. The position of water deficiency layer in all the communities' soil isinfluenced by position of the water moisture severe fluctuation layer and dense root systems layer. The seasonal dynamics of the water deficiency are closely relative to the plants' phonological season of the vegetation. They are divided into serious, medium and light water deficiency types, and the seasonal change of every layer is evident. Adaptable strategy of the communities for the soil water deficiency is differing with species.(5) Using the vegetations' succession and the mechanism of germination on the sand dune, it is determined for the suitable region & communities of sandy vegetation natural restoration. Through the relation of the soil water resource capacity and the stability of communities, the water stable mechanism of community is clear in the thesis. Depending on the response to mechanism of the spatial distribution pattern of high and low consumption for soil water, the artificial vegetation pattern should be established by near natural restoration way . The artificial vegetation pattern means that shrub & herb are main components and arbor scatters in them, named artificial grassland (savanna). Theoretically suitable density on natural sandy plant is depended on distribution range of the root systems.