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Ecosystems of the western United States are experiencing vegetation type conversions (VTC) in response to land-use change, climate warming, and their interactive effects with wildland fire. VTC is one of the most pressing management issues in the southwestern US, yet current strategies to intervene and address change often use trial-and-error approaches devised after the fact. This presentation discusses findings on VTC challenges, management responses, and outcomes from the collective experience of managers, scientists, and practitioners across the southwestern US.

Ecological reorganization across the region is not only extensive – it is complex, predominantly driven by high-severity wildfire. By a large margin, affected semi-arid forests convert to shrubland, while chaparral and sagebrush areas nearly always convert to non-native grasses. Management interventions in VTC areas most often attempt to reverse changes, although these efforts cover only a small portion of high-severity burn areas undergoing VTC. Efforts to facilitate VTC are rare but hold the potential to cover large spatial areas.

The presenter’s findings underscore that type conversion is a common outcome of high-severity wildland fire in the southwestern US. As the drivers increase with climate change, VTC appears increasingly likely in many ecological contexts, and may require management paradigms to transition as well.

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Following a wildfire, successful tree regeneration is mediated by multiple factors, from the microsite to landscape scale. This presentation demonstrates the importance of microsite conditions such as soil moisture and temperature in predicting conifer tree establishment. The speakers examined the footprint and behavior of a large 2018 wildfire in southern Colorado to understand how fire severity and post-fire logging influenced stand structure, fuels, vegetation, and soil microsite conditions. Their findings show that salvage-logged plots demonstrated lower daily average temperature and minimum soil moisture and higher fuel loading across most fuel size classes relative to unlogged plots, which also corresponded with a loss of dead standing wood and little to no canopy cover. Early post-fire conifer regeneration was low across all plots, but lower soil moisture and higher soil temperature negatively impacted the density of regeneration. Careful consideration of soil impacts and the associated changes to forest conditions should be taken when conducting post-fire logging to prevent detrimental effects on microsite conditions and forest recovery.