ARS | Publication request: FIELD-SCALE VARIATIONS IN PLANT AND GRASSHOPPER COMMUNITIES: A GIS BASED ASSESSMENT

Submitted to: Transactions in Geographic Information Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2002
Publication Date: June 1, 2002
Citation: Kemp, W.P., O'Neill, K.M., Cigliano, M.M., Torrusio, S. 2002. Field-scale variations in plant and grasshopper communities: a gis based assessment. Transactions in Geographic Information Systems.

Interpretive Summary: Geographic Information Systems are computer programs which permit us to study our world in map form. In this way, we are able to examine why and where insect populations are likely to become a problem. In this study, we examined the differences in grasshopper communities on a 1 square mile of grassland in southwest Montana. Our results showed that grasshopper communities were sensitive to the types of plants which were present in different parts of the grassland that we studied, both in terms of the species present and their abundance. Research of this type is important in helping us pinpoint where grasshopper problems are likely to begin, and permit to use these areas as early warning indicators of increasing populations. This work is central to our efforts to reduce the amounts of pesticides used in natural areas.

Technical Abstract: GIS technology allowed us to examine species-specific occurrence and abundance patterns of important grassland herbivore species through the use of appropriate statistical methods and the superior spatial representation commonly available in existing GIS packages. The study was conducted on an approximately 254 ha grassland area located 10 km south of Three Forks, Gallatin County, Montana, in the Agropyron spicatum province of the wester steppe region of the U.S.A. From an ecological perspective, grasshopper species distribution and abundance patterns observed on a local, non- uniform landscape (2.6 km2) were consistent with results found in other studies at the valley ( 1,400 km2), and state-level ( 237,000 km2) scales. Our observations at the local scale further demonstrate the importance of vegetation type and specific local stand physiognomies in structuring grasshopper populations. The application of results from studies conducted at various scales to the development of decision support tools for resourc managers is also discussed.