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Scale-dependent effects of landscape context on post- fire forest regeneration in the Northern Rockies: Final Report to the Joint Fire Science Program

Author(s): Erica A. H. Smithwick, Jamie L. Peeler
Year Published: 2021
Description:

We live in a changing world where climate change, built-up fuels, and human ignitions are causing fires to increase in size, frequency, and severity. In this changing world, managers are charged with stewarding resilient landscapes under the National Cohesive Wildland Fire Management Strategy. Additionally, federal law requires managers to devote resources to burned sites that are not restocking naturally. To meet these goals, accounting for a burned site’s surrounding landscape context (defined here as area and arrangement of nearby seed sources) could be fundamental to anticipating its resiliency and whether it restocks naturally. However, little is known about how landscape context interacts with scale, regeneration traits, terrain, and local site conditions to govern post-fire tree recovery. To address these knowledge gaps, we used field data, geospatial data, and statistical models to unravel spatial dynamics playing out across heterogenous post-fire environments. We found that seed source area and arrangement must be measured at relevant spatial extents that reflect regeneration traits. For wind-dispersed species, regeneration was associated with more seed source area and more complex arrangements at 50 m and 100 m spatial extents, but terrain mediated the relationships. For serotinous and resprouting species, regeneration was associated with less seed source area and less complex arrangements at 25 m, which was consistent with high severity fires that promote recovery. Additionally, we found that surrounding seed source area was more important than local site conditions in shaping subalpine fir presence and stocking density. But different thresholds occurred. Specifically, subalpine fir presence required 10% seed source area, while stocking density required 40%. Conversely, local factors like soil nutrients were associated with lodgepole pine presence – underscoring the effects of different regeneration traits. Overall, our findings provide considerations and thresholds to guide managers in better incorporating landscape context in their decision-making.

Citation: Smithwick EAH and Peeler JL. 2021. Scale-dependent effects of landscape context on post- fire forest regeneration in the Northern Rockies: Final Report to the Joint Fire Science Program Project ID 19-1-01-44. 25 p.
Topic(s): Fire Effects, Post-fire Management, Post-fire Rehabilitation
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 23786
Record updated: Nov 2, 2021