Get reliable rangeland science

Rangelands in the intermountain west provide multiple ecosystem services including sustainable forage for livestock and habitat for sage grouse. One common way to assess changes in the quality of these services is by monitoring changes in the canopy cover of herbaceous species. While many sampling methods now exist, some methods may be more appropriate than others depending on the cover classes measured and composition of the landscape. The purpose of this project is to assess which of two techniques will be more efficient and effective for evaluating herbaceous cover in a sagebrush dominated communities. We evaluated canopy cover of herbaceous species across 50 transects using two different methods, a modified Daubenmire technique and photography-based grid-point intercept (GPI). While Daubenmire estimates are taken in the field, GPI simply requires photos taken along the transect and analysis of these photos is performed via computer, by manually identifying species intersected by a one hundred pixel-grid on each image. Our results suggest that Daubenmire and GPI canopy cover estimates are different, indicating that the methods may not be compatible. The Daubenmire method allowed us to assess herbaceous cover beneath the shrub canopy, while GPI does not allow observers to easily quantify cover in the understory because the photos are taken above shrub canopies, which obstruct a portion of herbaceous cover. Our findings will enable us to evaluate which method is appropriate for sampling herbaceous canopy cover in sagebrush dominated ecosystems.