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Arid Land Geography ›› 2021, Vol. 44 ›› Issue (3): 629-636.doi: 10.12118/j.issn.1000–6060.2021.03.04

• Ecology and Environment of Tarim River Basin • Previous Articles     Next Articles

Ecosystem restoration of Populus euphratica forest under the ecological water conveyance in the lower reaches of Tarim River

ZHU Chenggang1(),Aikeremu Abula2,LI Weihong1,ZHOU Honghua1()   

  1. 1. State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China
    2. Xinjiang Tarim River Basin Authority, Korla 841000, Xinjiang, China
  • Received:2021-02-07 Revised:2021-03-08 Online:2021-05-25 Published:2021-06-01
  • Contact: Honghua ZHOU E-mail:zhuchg@ms.xjb.ac.cn;zhouhh@ms.xjb.ac.cn

Abstract:

The desert riparian forest distributed in the Tarim River Basin, with Populus euphratica Oliv. as the dominant species, is an important desert forest ecosystem in Central Asia. It provides multiple ecological services for the region, including resource supply, climate regulation, sand protection, soil and water conservation, and biodiversity protection, and an important P. euphratica gene pool. However, because of the large-scale development of water and soil resources in the upper reaches of the Tarim River Basin, the spatial distribution of water resources in its upper and lower reaches is gradually imbalanced, resulting in a 400-km river cutoff in the lower reaches of the Tarim River. As a result, P. euphratica forest ecosystems in the lower reaches of the basin were seriously degraded, desertification intensified, biodiversity was significantly reduced, and the ecological environment deteriorated day by day. In 2000, the Chinese government began to implement an ecological restoration project in the Tarim River and enforce ecological water conveyance to the lower reaches to save the dying P. euphratica forest. On the basis of the literature review, in this paper, the restoration of P. euphratica forest ecosystems under ecological water conveyance in the last 20 years in the lower reaches of the Tarim River was discussed and analyzed. Ecological water conveyance significantly raised the groundwater level, reduced the groundwater salinity and soil drought index, and effectively improved the habitat of P. euphratica forest ecosystems in the lower reaches of the Tarim River. The rejuvenation of P. euphratica was obvious: its crown width increased by 511.20% at 50 m away from the river, and its crown was full within 500 m away from the river; the average ratio of dead branches was less than 0.15. Because of water conveyance, on average, the radial growth of P. euphratica trunk increased by 62.80%, and the vegetation area of the desert riparian forest with P. euphratica as the constructive species increased from 492 km 2 in 2000 to 1423 km2 in 2020. Low-, medium-, and high-coverage vegetation areas increased by 20.80%, 448.00%, and 190.00%, respectively, in the lower reaches of the Tarim River. The ecological environment and vegetation community in the lower reaches of the Tarim River were sensitive to and fluctuated with changes in water conveyance. The existing ecological water conveyance mode barely ensured the effective regeneration of the P. euphratica forest in the lower reaches because of its lack of surface hydrological processes, and the P. euphratica population still maintained the “inverted pyramid” degradation age class structure after 20 years of ecologic water conveyance. There were significant sex ratio bias and sexual spatial segregation in the P. euphratica community in the lower reaches of the Tarim River, which was still in the primary stage of restoration and succession, and the degradation trend of the downstream P. euphratica community had not been completely reversed. On the basis of the review, in this paper, the problems in the ecological restoration of the lower reaches of the Tarim River were discussed, and suggestions for “optimizing the water conveyance scheme, expanding the water receiving area, and taking more active restoration measures” were put forward.

Key words: Tarim River, ecological water conveyance, Populus euphratica, ecological restoration