Fire and Invasions
Non-native plant invasions can change natural fire regimes by increasing fuel loads and continuity of fuels, which may alter fire behavior such as intensity, rate of spread, and extent. Fires can then promote additional plant invasions by exposing bare soil and releasing nutrients, resulting in a positive feedback between plant invaders and fire (Figure 1). This three year project funded by the Joint Fire Science Program (www.firescience.gov) is focused on evaluating the interaction between fire and the invasive annual grass Microstegium vimineum in eastern deciduous forests.
Microstegium is rapidly invading eastern forests, resulting in a widespread and dense layer of fine fuels following plant senescence. This layer of fuel provides an unnaturally continuous and flammable fuel bed potentially causing unusually intense fires. Increased fire frequency and severity in invaded areas may cause increased damage to native vegetation and result in unpredictable prescribed fire behavior and further invasions. We are studying the differences in fire behavior in invaded and native-dominated areas by examining large-scale prescribed burns at Big Oaks National Wildlife Refuge. In addition, to answer specific questions on timing of burns and increased invasions due to fire, we established experimental research plots with 10 different treatments manipulating the timing of fires and management options (Figure 2). We are evaluating vegetation impacts, soil characteristics, and invasion dynamics in addition to evaluating fire behavior in the treatment plots. This research will provide valuable information to land managers regarding the effects of Microstegium invasions on fire behavior, methods to prevent further invasions following prescribed fires, and how the timing of fires affects the spread of Microstegium.
Our goal is to answer the following specific questions:
- How do Microstegium invasions affect fire intensity and severity?
- How do prescribed fires and the timing of fires affect invasion dynamics?
- Do invasions alter the effects of fire on native species and habitats?
- What are the pre and post-fire management options for controlling Microstegium invasions?