Document Type

Dissertation - University Access Only

Award Date

2004

Degree Name

Doctor of Philosophy (PhD)

Department / School

Biology and Microbiology

First Advisor

W. Carter Johnson

Abstract

Wetlands in the Prairie Pothole Region are ecologically and economically significant. However, the number of natural freshwater wetlands continues to decline in the U.S. More intensive agricultural land-use and climate change in the future may prove to adversely affect prairie wetland quality and accelerate their current decline. The purpose ofthis study was to explore the effects of agricultural land-use on the hydrology and vegetation of prairie wetlands. The hypothesis was made that alternative agricultural land-use cover types will affect wetland water budgets in different ways. Then, the main question asked was: Is it possible to mitigate predicted climate change effects by varying agricultural land-use practices? To address this and other questions a new version of the single basin hydrologic model WETSIM was needed.

WETSIM 3.2 was developed based on previous well published versions of the model. The model was parameterized and calibrated using field and literature data. WETSIM 3.2 incorporated alternative agricultural land-use cover types through adjustments to runoff and upland evapotranspiration. Model simulations were run for unused grassland (native grass, smooth brome grass), managed grassland (grazed, prescribed bum), cultivated crops (row crop, small grain), and alfalfa hayland with averaged cutting effects. Changes in climate were also tested in model simulations in combination with different land-uses. Climate scenarios included a 2 °C and 4 °C increase, and a 10% and 20% increase or decrease in precipitation, and combinations of these.

Results showed that land-use affects wetland water budgets and linked hydro[1]ecological processes. This occurred primarily due to changes in runoff and upland evapotranspiration. Grasslands that received continuous grazing that removed 50% of the LAI and those that were prescribed burned (i.e. managed grasslands), provided the greatest potential to compensate for a warmer and/or drier future climate, compared to unused grassland and cultivated crops.

Wetlands that experienced improved water levels due to land-use also experienced more favorable vegetation dynamics, including more open water habitat and more time in hemi-marsh conditions.

Library of Congress Subject Headings

Wetlands -- Prairie Pothole Region.
Land use, Rural -- Environmental aspects -- Prairie Pothole Region -- Simulation methods.
Climatic changes -- Prairie Pothole Region -- Simulation methods.

Publisher

South Dakota State University

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Rights Statement

In Copyright