Rangeland Ecology & Management

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The use of digital photos to assess visual cover for wildlife in rangelands
Author
Carlyle, Cameron N
Fraser, Lauchlan H
Haddow, Cindy M
Bings, Becky A
Harrower, William
Publisher
Journal of Environmental Management
Publication Year
2010
Body

Grassland vegetation can provide visual cover for terrestrial vertebrates. The most commonly used method to assess visual cover is the Robel pole. We test the use of digital photography as a more accurate and repeatable method. We assessed the digital photography method on four forage grassland species (Pseudoroegneria spicata, Festuca campestris, Poa pratensis, Achnatherum richardsonii). Digital photos of 2-dimensional cutout silhouettes of three bird species sharp-tailed grouse, western meadowlark and savannah sparrow were used to model the impact of clipping (i.e., grazing) on visual cover. In addition, photos of artificial voles were used to model litter on cover available to small mammals. Nine sites were sampled and data were analyzed by the dominant grass species in each study plot. Regression analysis showed that digital photos (r2 160;= 160;0.62) were a better predictor than the Robel pole (r2 160;= 160;0.26) for assessment of cover. Clipping heights showed that clipping at less than 15 160;cm left the silhouettes 50% exposed. Digital photo analysis revealed that visual cover was affected by the type of grass species, with F. campestris 160; 62; 160;P. pratensis 160; 62; 160;A. richardsonii 160; 62; 160;P. spicata. Biomass and litter were both positively related to cover for small mammals.

Language
English
Resource Type
Text
Document Type
Journal Issue/Article
Journal Volume
91
Journal Number
6
Journal Pages
1366-1370
Journal Name
Journal of Environmental Management
Keywords
bunchgrass
Digital image analysis
grazing
litter
range management
Robel pole
wildlife management
remote sensing
British Columbia
Canada