Vegetation restoration and dynamic evolution analysis of landslide activity in the Wenchuan Earthquake area

A great mountain seismic often triggers a large number of co-seismic landslides, causing direct damage to local vegetation cover and growth. As an important indicator of landslide activity intensity, the vegetation recovery is of great significance for the activity of post-earthquake geo-hazards. However, due to the limitation of observational data, the current research on vegetation restoration process in earthquake areas is mostly on a small scale. In addition, there is insufficient understanding of the vegetation evolution mechanism in a large area and the relationship between vegetation and the activity of geological disasters. Therefore, this paper uses multi-temporal and long-time series (2000−2020) high-precision remote sensing images to study the vegetation restoration process in the Wenchuan earthquake area. By calculating vegetation recovery rates in different periods, we explore the universal law of vegetation restoration in a large range, and analyze the relationship between vegetation restoration and the change of landslide activity intensity. The results show that by 2020, 71.34% of the landslide area in the earthquake area has been better restored. The proportions of highly active, moderately active, low active and basically stable landslides are 17.6%, 12.4%, 17.7% and 52.3%, respectively. The surface recovery trend of co-seismic landslide indicates that the vegetation in the Wenchuan earthquake area is expected to recover to the pre-earthquake average level about 17 years after the earthquake. However, the process of vegetation recovery and changes in landslide activity are often subject to the combined effects of multiple factors. Although the vegetation recovery of landslide surface reflects the decline of landslide activity after the earthquake to some extent, the effects of the earthquake on landslide activity will last longer than the recovery of surface vegetation to the pre-earthquake level. Referring to the results of previous studies, this paper suggests that the post-earthquake landslide activity will last 25 years or more.The conclusion can provide reference for the assessment and prevention of post earthquake geological disasters in Wenchuan earthquake area.