The hill prairies of northeast Iowa: vegetation and dynamics

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1987
Authors
Ugarte, Eduardo
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Botany
Abstract

Patterns of plant community organization in 35 hill prairies from northeast Iowa were studied. The influence of grazing, woody species invasion and habitat factors on diversity and dominant species distribution was also investigated. The invasive process of the prairies by Juniperus virginiana was assessed by studying spatial distribution, age and size structure of four populations under different ecological conditions;The results indicate that hill prairies from northeast Iowa are part of a continuum that connects them to the tall grass prairie that once covered Iowa. They make up the driest part of the gradient and converge in structure with those hill prairies in Wisconsin, Illinois and Minnesota;Five community-types were distinguished and described. Andropogon gerardii, A. scoparius, Sporobolus heterolepis and Bouteloua curtipendula, the most important grasses, as well as smooth sumac Rhus glabra, behave differently under various conditions of topography, moisture availability and grazing intensity. Invasion of hill prairies by smooth sumac seems to be related with fire suppression. Smooth sumac is probably involved in a facilitation-like mechanism that promotes the establishment of eastern red cedar, Juniperus virginiana, when grazing is eliminated. Progressive or massive invasions of hill prairies by eastern red cedar can culminate in closed communities with total elimination of prairie species.

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Thu Jan 01 00:00:00 UTC 1987