Isabel Andrade Munoz,  

Sponsor or Client: 

Title:

Drivers of moss accumulation and regeneration in a post-wildfire boreal forest ecosystem

Abstract:

Climate warming is causing increases in fire frequency, severity, and size throughout the boreal forests of North America. This changing fire regime is likely to impact both overstory and understory vegetation successional trajectories. The overstory and understory are fundamentally intertwined through a complex series of biotic and abiotic interactions. Boreal forests are often characterized by black spruce-dominated stands with dense moss understories which can regulate domain stability (Johnstone et al. 2010). Direct and indirect effects of increasing wildfires on moss diversity could therefore fundamentally change the structure and function of boreal forest ecosystems. In this study, we investigate drivers of moss diversity in black spruce-dominated forest stands by measuring the impact of burn severity, shrub density, and litter coverage on moss growth. We hypothesize that burn severity will have a direct negative effect on moss growth as a result of propagule combustion and a direct positive effect on shrub density by exposing fertile mineral seedbeds. Furthermore, we hypothesize that shrub density will have a direct negative effect on moss growth by increasing shade coverage and an indirect negative effect on moss growth through litter deposition which is likely to suppress the moss layer. We quantified moss diversity and abundance across 10 sites throughout Interior Alaska and tested how each variable responded to fire severity, shrub density, and litter depth.