A forest vulnerability index based on drought and high temperatures

摘要: ABSTRACT Increasing forest stress and tree mortality has been directly linked to combinations of drought high temperatures. The climatic changes expected during the next decades – large increases in mean temperature, increased heat waves, significant long-term regional drying western USA will likely increase chronic mortality. aim this research is develop apply a new vulnerability index (FVI) associated with temperatures across Pacific Northwest region (PNW; Oregon Washington) MODIS Aqua era (since 2003). Our technique incorporates alterations canopy water energy exchange processes caused by spatially continuous land surface temperature (LST) evapotranspiration (ET), Parameter-elevation Relationships on Independent Slopes Model (PRISM) precipitation (P) data. With P ET, we calculate monthly balance variable for each individual pixel normalized type group (FTG), then difference corresponding LST (FSI). We extract pixel-specific (800-m resolution) statistically temporal trends FSI from 2003 2012 month (April October). FVI slope years, such that there month. Statistically positive slopes indicate interannual leading (positive FVI) given Positive values were concentrated months August September, peak occurring at different times FTGs. Overall, rates highest drier FTGs as Ponderosa Pine, Juniper, Lodgepole Pine. Western Larch Fir/Spruce/Mountain Hemlock groups occupy moister sites but also had relatively proportion values. Douglas-fir second largest total area due its areal extent study area. Based an analysis using imagery viewed Google Earth, confirm areas are greater amounts way conceptualize monitor based first-order principles potential be generalized other geographical areas.