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The Effects of Cattle Grazing on Vegetation in a Shortgrass Prairie Ecosystem

Abstract:: Grazing by large herbivores has profound effects on both the structure and function of shortgrass prairie ecosystems. In this exercise a grazed section of prairie on a working cattle ranch is compared to a less grazed section on an adjacent wildlife refuge. The Daubenmire canopy-coverage method is used to measure percent cover by plant species and bare ground. Vegetation within the Daubenmire quadrat frame is clipped and weighed to assess biomass by species. In addition, relative soil compaction and cowpie frequency are measured to characterize grazing intensity. Calculations of plant biomass diversity are made using the Shannon-Wiener Diversity Index (H). Sampling methods and hypothesis testing are introduced.

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Estimating Plant Densities Using Transects

Abstract:: By evaluating plant densities along linear transects in the field, students are introduced to the quantification of observable vegetation densities. Such quantification, in turn, introduces the formal study of ecology. Students should evaluate different local habitats in order to make comparisons.

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Abstract:: The exercise describes releve field methods and discusses the multivariate analysis of releve data. The application of releve data to problems of habitat evaluation, forest inventory, and research projects in Minnesota was presented by experts from the Minnesota Natural Heritage Program, the Minnesota County Biological Survey, and the Univ. of Minnesota. All participants received a releve handbook that covered the history of the method, field instructions, data-entry forms, and an overview of a menu-driven computer system SAS Version 5 used to manage a releve database.

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Abstract:: This ABLE major workshop took participants to Bogg's Rock, a granitic flatrock community that is in the early serial stages of succession. The line-intercept method of sampling was employed to allow the rapid characterization of the community structure. After species composition was defined, a simple statistical procedure was used to test one of several factors that might be controlling species distribution.