Doctoral Dissertation Research: Does Change in Fine-Scale Soil Properties After Fire Stimulate Exotic Species Colonization?

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Fire is a natural part of most forest ecosystems in the western United States. Forest managers utilize fuel reduction projects to lessen fire severity, often without considering potential negative ecological consequences of non-native plant species introductions. The establishment and spread of non-native species following fire may significantly alter the ability of native plant communities to recover. Factors such as fire severity, resource distribution, and soil alterations all play a role in where and how non-native plant species may establish in burned areas. This doctoral dissertation research project addresses the invasion potential across the forest/grassland ecotone following low severity fire by studying microsite changes from pre- to post-burn conditions. The two research questions of the proposed study are: 1) Are there significant differences in the biotic (vegetation attributes) and abiotic (soil moisture, temperature, nutrients) microsite conditions across the ponderosa pine/grassland ecotone of the Colorado Front Range following low severity fire, which would make the site more invasible? 2) In the post-fire landscape, following low severity fire, how are non-native plant species colonization patterns affected by the microsite patterns? Data collected from several research sites along this forest/grassland ecotone over the course of several seasons prior to prescribed burning provide information on variation in soil moisture and temperature and vegetation structure during times of near normal conditions. Following prescribed burning, the changes in microsite patterns may vary across the ecotone and impact the availability of sites for native and non-native species colonization. Many of the studies of fire effects to date address this question at coarser scales. This research applies a more fine scale approach to determine the mechanisms involved in the spread of non-natives into the forested landscape from a grassland matrix. This research will contribute to the understanding of the importance of microsite conditions and their effects on the potential for non-native plant species to move across ecotones after low severity fire. The use of this information will contribute not only to the overall understanding of the degree to which a recently burned area is susceptible to invasion by non-native species at the fine scale, but will also contribute to the integration of these fine scale mechanisms into landscape level responses to disturbance. This research will provide fundamental information that is necessary to support present and future forest management decisions in the western United States, in regards to prescribed fires and non-native species control. As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.