Effects of the Tarim River's middle stream water transport dike on the fractional cover of desert riparian vegetation

摘要

In recent years, attention has been paid to the restoration and conservation of desert riparian vegetation along the middle stream of the Tarim River. Quantifying the effects of the water transport dike on the ecological habitat of this riparian vegetation is fundamental to providing additional theoretical support to both researchers and policy makers. In this study, we conduct an analysis on the changes in the fractional vegetation cover gradient on both sides of the water transport dike in the middle stream of the Tarim River. This study also investigates the spatial-temporal changes in the fractional vegetation cover along the middle stream of the Tarim River, and the spatial variation in the rate of change from 2000 to 2013. Furthermore, this paper analyses the characteristics of the fractional vegetation cover under the influence of two types of ecological brakes. The findings reveal (1) a trend of declining fractional vegetation cover on both sides of the middle stream from 2000 to 2013, with the rates along the northern the southern banks being -0.2278 yr(-1) and -0.0294 yr(-1), respectively, (2) and overall, decreasing trend in the fractional vegetation cover with distance from the river channel along at two sections in the years 2000 and 2013. No obvious differences were observed inside the water transport dike. However, the effect of the water transport dike began from 1 km to 2.5 km, the range from 2.5 km to 13 km was mainly influenced by the dike on the northern bank of the Yingbazha-Osman, while the effect of the water transport dike on the southern bank of the Yingbazha-Osman, began from 1.5 km and gradually increased until 4.5 km. The area from 4.5 km-10 km was primarily affected by the water transport dike and reached a highly steady state at 10 km, which persisted until 30 km. The fractional vegetation cover in the years 2000 and 2013 were similar for Osman-Korla, especially on the southern bank, but fluctuations appeared on the northern bank. (3) fractional vegetation cover change rate showed different characteristics outside the water transport dike; different types of ecological brakes also imposed different effects on both sides of the river channel. (C) 2016 Elsevier B.V. All rights reserved.