Negative Effects of Ecological Restoration on Slope Stability in Chinese Yellow River basin

Abstract

<p><strong>Abstract</strong>: With the implementation of the large-scale “Grain for Green” program, vegetation in the Chinese Loess Plateau (CLP) has been remarkably restored, which is believed to in turn have significantly mitigated soil erosion in the Yellow River basin (YRB). However, various local-scale evidences suggest that plants may also promote slope failures; whether the large-scale ecological restoration in the YRB has posed negative effects on slope stability, remains an open question. Here, we inspect the effects of ecological restoration on slope stability in the YRB by quantitatively correlating the distribution of landslides with the variation of vegetation cover. We pick out those landslides located in areas with increasing vegetation continuous fields (VCF), and group them into eight major spatial clusters. We find that, landslide clusters with higher increasing gradients of VCF generally have higher proportions of active landslides, revealing that ecological restoration has posed negative effects on slope stability in the YRB. We then clarify that, soil moisture is "U-shaped" correlated with the negative effect intense index (NEII) of ecological restoration on slope stability, and a specific threshold of soil moisture correlate a minimum NEII. Finally, we demonstrate that, the ecological restoration of more than 20 years in the YRB has caused widespread increasing but fluctuation of soil moisture and evaporative stress factor and induced negative effects on loess strength and slope stability in the CLP. We show that, in areas with limited water-source, excessive revegetation will damage soil strength and reduce soil resistance because its water-consumption will exceed its water-conservation. This contribution suggests that, ecological restoration should be restrained to a sensible extent for effective soil-water conservations and landslide hazard mitigations, especially in arid and semi-arid areas like the CLP.</p>