Effects of Vegetation Treatments on Soil Invertebrate Populations in the Great Basin Rangelands

Document Type

Student Presentation

Presentation Date



School of Public Service


Environmental Studies

Faculty Sponsor

Beau Hansen


Controlling invasive species in Great Basin rangelands is critically important in order to preserve sagebrush (Artemisia tridentata) habitat. In particular, the spread of cheatgrass (Bromus tectorum) in the Great Basin has altered patterns of fire disturbance and has led to a decline in habitat essential to many native Western species. A number of studies have looked into the efficacy of different herbicide and bacteria treatments in regard to controlling cheatgrass: however, it remains poorly understood how these treatments are impacting soil invertebrate species within treated areas. The objective of this research project was to determine the effect of various herbicide treatments on soil invertebrate communities. This is a new facet of an existing study started in October of 2016; the Idaho Sage Grouse Action Team’s soil bacteria project (ISA-BAC) being conducted through the United States Geological Survey. The test plot used for this study is approximately 25 miles south of Boise on BLM land, consisting of 24 plots that are 25’x 25’ft each.

The plant community in the test area consists largely of crested wheatgrass (Agropyron cristatum) and cheatgrass (Bromus tectorum). Eight different treatments were investigated; each repeated 3 times. At each plot, soil core samples were collected before and after treatment, and placed in a Berlese-Tullgren funnel system to isolate soil invertebrates. Once isolated, invertebrates were viewed under a microscope for classification. Results are still being tabulated. However, the herbicides imazapic and rimsulfuron are expected to have a positive impact on soil invertebrates based on previous studies. Similar positive effects are expected following the introduction of the Pseudomonas florescens D7 soil bacterium. The next steps of this project are to replicate it in the spring and at the other two ISA-BAC study sites.

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