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The Effects of Prescribed Fire Seasonality on the Invasive Grass Bothriochloa ischaemum and Native Species

by Oline, Alice

Abstract

Invasive species are becoming increasingly problematic as human activities and climate change accelerate their spread to new areas. The invasive grass Bothriochloa ischaemum (King ranch bluestem) has taken over large portions of the savanna on the Edwards Plateau in central Texas. Given its pervasiveness, it greatly reduces the populations of native grasses and forbs, and land managers are looking for effective ways to control this species. Recurring fire is necessary to maintain savanna ecosystems; this study aims to determine the most effective timing of fire for controlling B. ischaemum and maintaining a diverse savanna ecosystem. An unreplicated randomized block design was used, in which plots were burned at different times of year during 2016, or left unburned as a control. Pre-fire moisture data, soil temperature data from the duration of the burn, and post-fire plant species data were taken from each plot. These data show that there is a non-significant correlation between August burns and higher fire intensity, and a slight negative correlation between fuel moisture content and higher fire intensity. There was a nonsignificant trend towards lower species richness in unburned plots. On average, a plot burned in August or October was less likely to have B. ishcaemum than a plot burned in February or April, or left unburned. Prescribed burns successfully increased the abundance of native perennials, especially when done in the late summer. These results are probably due to differences in plant phenology at the time of each fire. Native plants are adapted to summer fires, while B. ischaemum could be at a vulnerable phenological stage during the summer. These findings have important implications for the management and restoration of central Texas grasslands. We recommend that land managers use prescribed burns during late summer in order to control B. ischaemum and boost ecosystem health.

Note

The author has given permission for this work to be deposited in the Digital Archive of Colorado College.

Colorado College Honor Code upheld.

Includes bibliographical references.

Administrative Notes

The author has given permission for this work to be deposited in the Digital Archive of Colorado College.

Colorado College Honor Code upheld.

Copyright
Copyright restrictions apply.
Publisher
Colorado College Tutt Library
PID
coccc:29901
Digital Origin
born digital
Extent
32 pages : illustrations, map(s)
Thesis
Senior Thesis -- Colorado College
Thesis Advisor
Rebecca Barnes Lynne Gratz
Department/Program
Environmental Program
Degree Name
Bachelor of Arts
Degree Type
bachelor
Degree Grantor
Colorado College Tutt Library
Date Issued
2018-05