Silver Sagebrush Community Associations in Southeastern Alberta, Canada

Abstract

Greater sage-grouse (Centrocercus urophasianus) habitat in southeastern Alberta is limited by the distribution of silver sagebrush (Artemisia cana Pursh). We conducted a landscape assessment of silver sagebrush throughout the current range of sage-grouse in southeastern Alberta. Black-and-white aerial photography acquired in the fall of 2001 was used to map silver sagebrush. Contact print stereo pairs were interpreted using a stereoscope and initially classified into 1 of 13 site classes based on soil type and landscape feature (e.g., recent agriculture). Each site polygon was further broken down into smaller polygons based on the percentage of silver sagebrush occupancy, density distribution, and height. A total of 4 626 site polygons were identified and classed into 1 of 13 site classes. To ensure all assumptions of statistical tests were met, the data set was reduced to 9 site classes. The mean percentage of silver sagebrush occupancy was significantly different between the 9 site classes (F = 285.00, df = 8, P < 0.001). The lotic site class had the highest mean percentage of occupancy, followed by overflow and old cultivated site classes. The frequencies of density distribution were not equal for all site classes (Pearson’s chi-square = 5 727.09, df = 72, P < 0.001). Lotic had greater than expected occurrences in distribution classes 8 through 12 whereas overflow had greater than expected occurrences in distribution classes 8 and 10. The frequencies of height class were not equal for all site classes (Pearson’s chi-square = 4 382.15, df = 24, P < 0.001). Lotic and overflow sites had greater than expected occurrences in the mixed and tall height classes, whereas blowouts, loamy and saline lowlands had greater occurrences in the small height class. Understanding the occupancy, density distribution, and height of silver sagebrush across the landscape will assist in understanding the resource selection patterns and management of sage-grouse in Alberta, Canada.