Analysis of Changes in Vegetation Condition in Grasslands National Park Using Remote Sensing

Abstract

This study uses a variety of change detection techniques in order to study changes in vegetation in Grasslands National Park, Saskatchewan, Canada. Techniques such as image differencing and principal component analysis were used to determine what types of changes in vegetation have occurred over the last thirty years. A normalized difference vegetation index (NDVI) was also used to highlight changes in vegetation productivity. Grasslands National Park is located in Southern Saskatchewan along the Canadian-US border. The Frenchman River runs through the study area. Three Landsat images were acquired. The spatial extent of the images is from about 47deg 50'N to 49deg50'N and 106deg30'W to 108deg20'W. The three images were first georeferenced to one another, and then clipped to include the area from 49degN to 49deg15'N and from 106deg30'45Wto 106deg45'56W. Change analysis techniques were then performed on the data. These included a Visual Analysis, a Post-Classification Analysis, NDVI Image Differencing and a Principal Component Analysis. Analyses were performed comparing the 1978 and 1987 images, the 1987 and 1999 images and the 1978 and 1999 images in order to get a better understanding of the nature of changes. The analyses showed a decrease in vegetation productivity around the Frenchman River and other small bodies of water from 1978 to 1987 and from 1987 to 1999. There is a lot of change in the agricultural areas. These areas saw both increases and decreases in productivity. It is possible that changes in vegetation productivity around water bodies is related to climate variations and the changes in agricultural areas are related to changes in land use. It will be necessary in a future study to acquire climatological data for the area, as well as information about the conversion from agricultural land to native prairie. It is also necessary to acquire images from other years to better understand the changes.