MS Thesis Defense | Kayla Morrison

Evaluating fire frequency on Microstegium vimineum seed bank dynamics and nutrient cycling in the Central Hardwoods

Across eastern North America, reintroducing low-intensity surface fires to restore historical open forests is complicated by invasive non-native grasses that alter biogeochemical cycling and trigger positive fire-invasion feedbacks. My thesis evaluated how fire frequency and experimental burning affect the population dynamics of the invasive grass Microstegium vimineum, alongside soil carbon and nitrogen stocks in southern Illinois. Across a fire frequency gradient, M. vimineum population growth rates declined with frequent burning due to negative effects on seed bank dynamics. Furthermore, repeated fires left a distinct chemical signature in the mineral soil with pyrogenic carbon accumulating over time. This work provides insight into the influence of fire frequency in controlling invasive grasses and the cumulative effect it has on total carbon and nitrogen stocks.