| Quantitative relationship between cultivated land expansion and natural vegetation degradation in the lower reaches of the Tarim River |
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| DOI：10.7606/j.issn.1000-7601.2018.02.33 |
| Key Words: the lower reaches of Tarim River cultivated land expansion natural vegetation degradation groundwater depth ecological water conveyance |
| Author Name | Affiliation | | GUO Hong-wei | State Key Laboratory of Desert and Oasis Ecology, Xinjiang institute of Ecology and Geography, CAS, Urumqi, Xinjiang 830011, China
University of Chinese Academy of Sciences, Beijing 100049, China | | XU Hai-liang | State Key Laboratory of Desert and Oasis Ecology, Xinjiang institute of Ecology and Geography, CAS, Urumqi, Xinjiang 830011, China | | LING Hong-bo | State Key Laboratory of Desert and Oasis Ecology, Xinjiang institute of Ecology and Geography, CAS, Urumqi, Xinjiang 830011, China | | Parhatjan·Ahmait | Xinjiang Agricultural University, Urumqi, Xinjiang 830011, China |
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| Abstract: |
| In recent years, a large area of natural vegetation has been reclaimed as cultivated land because of the development of water and soil resources in the lower reaches of the Tarim River, and the original balance of the ecological system has been broken. However, the quantitative relationship between the cultivated land expansion and the natural vegetation degradation has not been clear. Based on 14 times ecological water conveyance data, groundwater depth changes after the ecological water conveyances data, remote sensing image data and social economic data, this paper analyzed the response characteristics of groundwater depth to ecological water conveyance and constructed a quantitative relation model between ecological water conveyance volume and groundwater depth. Then, the area proportion of cultivated land expansion and natural vegetation degradation was proposed, and the profit and loss after natural vegetation converted to cultivated land were calculated. The results showed that: (1) after 1×108 m3 ecological water was occupied by cultivated land expansion, groundwater depth on both sides of the river decreased by an average of 1.01 m. P. euphratica forest with a distance of 280～640 m from the river and an area of 50.40 km2 began to decline gradually from normal growth, and P. euphratica forest with a distance of 1 760～1 800 m from the river and an area of 5.60 km2 began to die; (2) the area ratio of cultivated land expansion and P. euphratica declining and decaying were 1∶3.6 and 1∶32.7, respectively; (3) although the output value per unit area of cultivated land (136.91×104 yuan·km-2) was higher than that of woodland and grassland (11.42×104 yuan·km-2), but the total output value of woodland and grassland (3.47×108 yuan) was higher than that of cultivated land (11.44×108 yuan). Consumed equal volume of water, the output value of woodland and grassland (2.85 yuan·m-3) was higher than that of cultivated land (2.11 yuan·m-3). From the viewpoint of sustainable development, the value of woodland and grassland was higher than that of cultivated land, and the ecosystem service function was greater than the productive function. Therefore, the disorder expansion of cultivated land should be strictly limited. This study provides a theoretical basis for the study area to limit the disorderly cultivated land expansion. |
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