Detecting Woody Plant Cover in the Foothills Parkland and Montane Ecoregions of Southern Alberta

Grasslands globally are threatened by loss and degradation as shifting factors in climate and management put them at risk. These grassland ecosystems support local economies and are a center of biodiversity, which makes understanding the risks that affect them key to effectively protecting them. One major risk to grasslands is woody plant encroachment, and reliable management hinges on understanding its patterns. A major challenge of woody plant encroachment is detecting it at early stages (<20% cover). This study investigated the utility of a combination of environmental features and remotely sensed data for differentiating varying levels of woody plant encroachment in a montane Canadian grassland. The response of woody species to environmental factors including slope and available moisture varied by individual species. As in past studies, it was challenging to separate the early stages of encroachment using base spectral bands or NDVI, even with the use of higher-resolution satellite imagery. Bands in the yellow and red wavelength regions both showed promise for shrub detection, providing more between band separability and key modeling components. The spatial resolution and band combinations used here were able to model woody plant cover levels, helping to facilitate the implementation of effective management in combating woody plant encroachment.