| Landslides caused by mountain earthquakes often cause serious damages to the natural ecosystem in mountainous areas.Most countries along the ' Belt and Road' are located in the Pacific rim seismic belt and the Eurasian seismic belt,two major seismic zones in the world.Earthquake risks are very high,and the earthquake disasters in history are serious,which seriously threatens the safety of human life and property.It is of great significance to study the process of vegetation restoration in earthquake-triggered landslides for the evaluation of ecosystem restoration and ecological environment protection after strong earthquake disturbances.In this paper,the 7.6-magnitude Kashmir earthquake in 2005 was taken as an example to monitor the dynamic changes of vegetation in the region over a decade after the earthquake to understand the state of vegetation recovery in the region after the earthquake and provide support for the ecological recovery and reconstruction in the disaster area.Using the MOD13Q1 NDVI data at 16-day interval from February 2000 to December 2016 and the high-quality multi-temporal terrestrial satellite(Landsat)data available in the seismic region,the vegetation index changes before and after the earthquake in the seismic region calculated by the image difference method were used to extract the landslide distribution in the seismic region.Using the method of time series analysis,the trend components of NDVI time series of vegetation on the landslide triggered by the Kashmir earthquake were extracted,and the dynamic change rules of vegetation in the region over ten years after the earthquake were analyzed.Our results show that:(1)A total of 913 landslides occurred in the earthquake area(2,757 km2),with a total area of about 15.99 km2,covering 0.58%of the total area of the earthquake area,including more than 70%of the landslides with an area less than 1 hm2.Through the analysis of the spatial distribution characteristics of landslides,it is found that most of the landslides in the earthquake area are located in the area below 2200 meters above sea level,and more than 80%of the landslides are located in 800?1600 meters.Earthquake zone of landslide are mainly distributed in 10° to 40° slope within the scope of the whole,the slope is less than 30 0 area,landslide area ratio increases with the increase of slope,the slope is greater than 30° area,landslide area ratio decrease with the increase of slope;More than 60 percent of the landslide area is in the southeast,south and southwest.(2)Vegetation in these hard-hit areas was in a state of slow recovery after the earthquake,and the overall vegetation index showed a gradual upward trend from 2005 to 2016.At the end of 2016,only 39.45%of the landslide NDVI on the 113 pixels in the earthquake zone has recovered to the pre-earthquake level,and the vegetation index on some landslides has not yet recovered to the pre-earthquake state.According to the prediction by fitting linear equation,the post-earthquake recovery of 43.49%landslide needs 12-20 years,the post-earthquake recovery of 9.54%landslide needs 21-30 years,the post-earthquake recovery of 6.24%landslide needs 31-41 years,and the pre-earthquake recovery of 1.28%landslide needs more than 40 years.(3)The vegetation on the landslide recovers fastest in the range of 1000?1200m,and the area recovered from the landslide is positively correlated with the elevation in the range below 1400m.In the slope range of 20?30°,the vegetation of the landslide recovers fastest,followed by the slope range.In the slope range of 10?40°,the restored landslide pixels are positively correlated with the slope.Landslide pixels are distributed in the southwest and south directions,followed by the southeast and west directions,and the south and southwest directions recover the fastest. |
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