This research is designed to understand the mechanistic connections among vegetation, the organic soil layer, and permafrost ground stability in Alaskan boreal ecosystems. Understanding these linkages is critical for projecting the impact of climate change on permafrost in ecosystems that are subject to abrupt anthropogenic and natural disturbances (fire) to the organic layer. We hypothesize that major threshold change is more likely to occur in ecosystems that are already at the margins - forests that, historically, are already stressed - and in fires that are at the extremes in terms of size or severity. We expect that severe fires occurring in forest stands that have not experienced deep burning as part of the recent fire cycle will consume a larger proportion of the organic soil layer and have the greatest potential for permafrost destabilization. We hypothesize that drought-stressed forest stands are more likely to shift to an alternate, deciduous, successional trajectory after fire and that moss percent cover and organic soil re-accumulation are negatively related to the percent cover of deciduous canopy tree species. This project is funded through the US Department of Defense (DoD). The Strategic Environmental Research and Development Program (SERDP).