Landscape matters: Predicting the biogeochemical effects of permafrost thaw on aquatic networks with a state factor approach

Permafrost thaw has been widely observed to alter the biogeochemistry of recipient aquatic ecosystems. However, research from various regions has shown considerable variation in effect. In this paper, we propose a state factor approach to predict the release and transport of materials from permafrost through aquatic networks. Inspired by Hans Jenny's seminal description of soil-forming factors, and based on the growing body of research on the subject, we propose that a series of state factors-including relief, ice content, permafrost extent, and parent material-will constrain and direct the biogeochemical effect of thaw over time. We explore state-factor-driven variation in thaw response using a series of case studies from diverse regions of the permafrost-affected north, and also describe unique scaling considerations related to the mobile and integrative nature of aquatic networks. While our cross-system review found coherent responses to thaw for some biogeochemical constituents, such as nutrients, others, such as dissolved organics and particles, were much more variable in their response. We suggest that targeted, hypothesis-driven investigation of the effects of state factor variation will bolster our ability to predict the biogeochemical effects of thaw across diverse and rapidly changing northern landscapes.