Spatiotemporal Dynamics of Oak Forest of Zagros in Responce to Drought Case Study: Oak Forest of Lorestan

The Zagros Woodland is one of the main components of Zagros ecosystem that has significant role in water and soil conservation. Drought, as one of the climatic hazards, can have dramatic effects on forest cover. Therefore, detecting the spatiotemporal dynamics of the forest in response to drought is very important. The main objective of this study was to detect the spatiotemporal relationship of forest cover of Lorestan province in response to annual drought. In this regard, the Enhanced Vegetation Index (EVI) values were extracted from Landsat 5 and 8 images for the period 2017-2017. The Standardized Precipitation Index (SPI) was calculated for the mentioned period using monthly rainfall statistics of 9 synoptic stations in the region. By using spatial correlation analysis, the relationship between annual forest area and drought index was investigated and finally, sensitivity function of spatial variation of forest cover was obtained by fitting a linear model. The results of field sampling showed that EVI threshold> 0.4 can be considered as the province's forest cover threshold. Correlation analysis between forest cover and drought indicated that the 18-year time series of forest cover had a significant correalation of 0.68 with SPI (0.95 confidence level). The results of development of sensitivity function to SPI index indicated that the forest cover had significant sensitivity to drought so that for each 0.1 unit change in the SPI index the forest cover area will change as 14880 ha in the same direction.