Long-term changes of <Emphasis Type="Italic">Tamarix</Emphasis>-vegetation in the oasis-desert ecotone and its driving factors: implication for dryland management |
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Authors: | Quanlin Ma Jihe Wang Xinrong Li Shujuan Zhu Hujun Liu Kejie Zhan |
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Institution: | (1) Key Laboratory of Combating Desertification of Gansu Province, Gansu Desert Control Research Institute, 733000 Wuwei, Gansu Province, China;(2) Shapotou Desert Research and Experiment Station, Cold and Arid Regions Experimental and Engineer Research Institute, Chinese Academy of Sciences, No. 260, West Donggang Road, 730000 Lanzhou, Gansu Province, China |
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Abstract: | The Oasis-desert ecotone plays an important role in ensuring oasis ecological security. This study was to determine the main
factors on the changes of desert vegetation in the oasis-desert ecotone, and to understand the mechanisms of the long-term
changes. During past 50 years, the dominant plant species of Tamarix-vegetation in the Minqin oasis-desert ecotone changed from mesophytes to xerophytes and finally to super-xerophytes. The vegetative
distribution area (belt width of Tamarix-vegetation between desert and oasis) markedly decreased from 1,000 m past to 30 m current. The coverage of Tamarix bushes reduced from 25 to 7%. The importance value (IV) of the bushes fell from 0.957 to 0.752, and Simpson index decreased from 0.702 in 1959–0.589 in 1992, and then increased
to 0.712 in 2002. These changes in vegetation were closely related with the rapid decrease of groundwater table and the reduction
of soil moisture due to unsustainable use of water resources for expanded agriculture development. These findings suggested
that the change of Tamarix-vegetation in the oasis-desert ecotone was a process of vegetation degradation and concurrent desertification. The maintaining
of stable groundwater and Tamarix-vegetation is a vital prerequisite for dryland management, especially, conserving ecological health of oasis-desert systems. |
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