Spatial and temporal trends in vegetation index in the Bonanza Creek Experimental Forest

Abstract

Climate has warmed substantially in boreal Alaska since the mid-1970s. The direct effects of rising temperatures on sub-Arctic ecosystems are already being observed in the form of drought stress, increased fire frequency and severity, and increased frequency and severity of herbivorous insect outbreaks. These effects of climate change are having a direct impact on the vegetation of the boreal forest and leading to a decreased remotely sensed normalized difference vegetation index (NDVI), which is an effective proxy for landscape-scale plant productivity and photosynthesis. Therefore, NDVI is a useful tool to examine landscape-scale changes in vegetation over time, especially in the context of known climate change. The overarching goal of my research was to assess the change in vegetation index at multiple scales over a period of 23 years at Bonanza Creek Experimental Forest. I used a combination of remote sensing and field sampling to examine trends in NDVI across landscape units, topographic classes, and plant communities. My project consists of two main parts: 1) Create a floristically-based landcover classification through field sampling and incorporating the field data into a map using satellite imagery and 2) Examine trends in the vegetation index using 11 Landsat TM and ETM+ images from 1986-2009. By using Landsat imagery and doing a landcover classification of my study area I was able define trends in NDVI to specific landscape units, topographic classes, and plant communities in the study area.