Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Master of Science (MS)

Department / School

Natural Resource Management

First Advisor

Alexander J. Smart

Abstract

Invasive introduced cool-season grasses such as Kentucky bluegrass (Poa pratensis L.) and smooth bromegrass (Bromus inermis Leyss.) have reduced native grasses in the northern tallgrass prairie. Fire and grazing have been identified as viable techniques for controlling introduced cool-season grasses in native tallgrass prairie. The objective of this study was to determine the effects of combinations of spring burning, intensive clipping, and low-level atmospheric nitrogen deposition on species foliar cover. Three experimental sites were established in eastern South Dakota (Brookings, Miller, and Volga). The experimental design was a split-split plot with 4 replications. The whole plot consisted of spring (late April to early May) burning or no burning, the subplot consisted of weekly clipping to$. 7cm in May, and the sub-subplot consisted of early June application of 0 or 15 kg N/ha. Treatments and data collection were initiated in 2009 with annual and biennial application frequency evaluated for 2010. Leaf area index was measured in early and mid-June and in late June/early July. Foliar cover estimates of major plant functional groups were conducted in late June/early July and late August/early September. Big bluestem reproductive tillers were counted in late August/early September 2010. V Individual and combined effects of late spring fire and May clipping significantly (P=0.05) reduced leaf area index throughout June and decreased introduced grass cover and increased native warm-season grass cover in late June/early July and late August/early September 2009 and 2010. In addition, in 2010 the annual frequency had similar effects and increased big bluestem reproductive tillers in late August/early September 20 I 0. Response to nitrogen application was mixed. Nitrogen appeared to offset reductions in introduced grass cover caused by fire and clipping at Brookings, Miller, and Volga, but it also enhanced native warm-season grass cover at Brookings in late June/early July in 2009 and 2010. Annual late spring burning and intensive weekly clipping in May were effective management strategies for reducing invasive cool-season grass in eastern South Dakota. The results support clipping or grazing as a viable alternative to prescribed fire for managing invasive cool-season grasses. Long-term evaluation is needed to identify what frequency interval and treatment combinations are most effective for controlling introduced grass species to permanently restore and conserve native tallgrass prairie in the northern Great Plains.

Library of Congress Subject Headings

Grasses -- Control -- South Dakota
Invasive plants -- Control -- South Dakota
Prairie ecology
Grassland restoration

Publisher

South Dakota State University

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Rights Statement

In Copyright