Faculty advisor University of California, Riverside Riverside, California, United States
Background/Question/Methods
Early life stage traits, known as regeneration traits, are integral to the post-fire recovery process as they may dictate successful establishment and survival under post-fire stressors, yet are largely understudied and may differ from adult traits for perennial species. These regeneration traits can interact with post-fire regeneration strategies (eg. resprouting, seeding) and environmental conditions (eg. aspect type) to structure differences in the successional trajectory of communities. Understanding the mechanisms of post-fire recovery is key to preventing habitat type conversions such as from altered disturbance regimes. Therefore, our research objective was to evaluate how regeneration traits and strategies link to post-fire establishment and recovery in woody perennial species. We asked, how do 1) functional traits differ across life stage and aspect, 2) regeneration traits and strategies mediate survival, and 3) regeneration traits and strategies link to recovery over time? To answer these questions, we collected leaf functional traits across northeast and southwest aspects for regenerating species within the Holy fire burn scar in southern California’s Cleveland National Forest and for adults in nearby unburned areas. We surveyed survival of tagged individuals and community composition within these different community types during the first two years post fire.
Results/Conclusions
We found regeneration traits were resource-acquisitive while adult traits were stress-tolerant, highlighting the need to study regeneration traits during recovery. Regeneration traits did not differ across aspect type but rather by regeneration strategy, where resprouters were more stress-tolerant (low Specific Leaf Area, SLA) and seeders were resource-acquisitive (high SLA) during the first year of recovery. Regeneration strategy rather than regeneration traits mediated survival, where resprouters had 100% survival rates regardless of trait value, but seeder survival varied independently from regeneration traits. We found the contribution to post-fire recovery from resprouters and seeders differed over time, where resprouters contributed more in year one but by year two seeders and resprouters had similar cover, suggesting regeneration strategy mediates initial recovery but not long term recovery. For community traits weighted by species abundance, northeast aspects favored resource-acquisitive strategies while southwest aspects favored stress-tolerant strategies - showing a tradeoff in community function across aspect type. Overall, regeneration strategy can play a larger role than regeneration traits in the first year of establishment, but over time the importance of regeneration strategy and traits may change. Our work highlights the need for long-term studies to disentangle how and when regeneration traits mediate recovery after a disturbance.
