Introduction

Regeneration in the Face of Climate Change

Forests provide essential ecosystem services, from timber production to biodiversity conservation, and hold deep cultural significance for Indigenous communities (Blouin, 2003; Marles et al., 2000). Wildfires are a natural part of these ecosystems and often promote renewal by recycling nutrients and creating space for regeneration (Johnstone et al., 2016). However, in contrast to historical disturbance regimes, modern fires are becoming larger, more frequent, and more severe, contributing to widespread forest loss across North America (Tyukavina et al., 2022). These severe fires are often followed by harsher conditions—hotter temperatures, greater exposure, and reduced soil moisture—that contribute to recruitment failure, or the inability of seedlings to establish (Ibáñez et al., 2017; Bouchon & Arseneault, 2004).

To address this challenge, we examine how residual standing structures, specifically snags, influence microsite variation and seedling performance within a burned subalpine forest in Alberta, Canada. Despite their prevalence in post-fire landscapes, there remains insufficient understanding of how snags affect local growing conditions. This knowledge gap is especially important in the context of salvage logging, where retaining or removing snags could have long-term consequences for recovery trajectories.

Although the hydrological role of live trees is well documented, it is less clear whether dead trees continue to intercept precipitation, redistribute rainfall as stemflow, or influence soil moisture patterns (Breshears et al., 2008). To explore this, our first objective is to quantify rainfall partitioning into stemflow and throughfall using open rain gauges and rainfall redistribution measurements, and to assess how these dynamics vary with stand density and snag structure. 

With the potential influence on microsite quality, the second objective of this research is to investigate spatial variation in soil moisture by comparing conditions in open areas, between snags, and at the base of snags. Snags may alter soil moisture by providing shade or redirecting precipitation, potentially creating more favorable microsites.

To explore whether these microsite conditions translate into biological effects, our third objective is to assess how seedling performance responds to variation in snag proximity and treatment type. Aspen seedlings were planted under snags, between snags, and in open areas, with additional manipulations to stemflow via diversion collars. These paired measurements of microclimate and growth allow us to evaluate the functional role of snags in post-fire regeneration.

Salvage logging, commonly used to recover economic value and reduce fuel loads, can substantially alter structural legacies. By linking hydrological processes to seedling performance, this study provides insight into whether and how snag retention may support recovery. Our goal is to inform whether leaving snags, either sparsely distributed or in dense clusters, can enhance soil moisture retention and seedling survival, supporting climate-resilient management of burned forests.