US-IALE 2018

AUTHORS: Jamie L Peeler*; Erica Smithwick – The Pennsylvania State University

ABSTRACT: Forests in the western United States are projected to experience more frequent and larger fires in coming decades due to increased temperatures, earlier spring snowmelt, and longer fire seasons associated with global warming. Due to this anticipated increase in fire activity, recent research has identified factors that influence post-fire forest resilience: distance to unburned area, soils, and post-fire climate. However, few studies have explored how the arrangement and interactions of these factors contribute to forest resilience, especially at the landscape level. Spatial resilience is an important framework for understanding the spatial links that support forest resilience in an increasingly fire-prone world. In particular, spatial resilience leverages a useful theoretical lens for tackling the challenge: network theory. Here we propose a framework for using network theory to predict how mixed conifer forests will reorganize following fire in the Greater Yellowstone Ecosystem. Links to re-establish nodes are determined by interactions between dispersal and local site conditions, as re-establishment is dependent on material legacies (e.g. seeds and resprouts) reaching nodes with suitable post-fire climate, soils, and topography. However, networks may differ based on post-fire regeneration traits: resprouting, having an aerial seedbank that releases seeds when cued by fire (serotiny), and re-seeding via wind or animal. In post-fire landscapes, such insight is critical because fire may interact with dissimilar networks differently, causing some to become brittle more rapidly. This causes nodes to become less connected or less suitable for certain material legacies, while other material legacies maintain their connectivity. If mismatches in connectivity reach a threshold, then a node may re-establish differently. Accordingly, we ask: Do the structures of seeding, sprouting, and serotinous networks differ and how does fire alter these networks? Can connectivity metrics be used to predict how forests will reorganize post-fire?