With more frequent wildfires and variable precipitation events, understanding post-fire recovery mechanisms is vital to prevent plant invasions and habitat type-conversion. Early life-stage traits (regeneration traits) are integral to this recovery process as these traits may dictate successful establishment and survival under post-fire stressors, yet are largely understudied and may differ from adult traits. Post-fire regeneration traits and environmental filtering (ex. aspect type) can interact to structure the successional trajectory of communities, resulting in patchy recovery over a landscape, where some sites recover while others do not. Therefore, our research objectives were to identify key regeneration traits and evaluate how these traits link to woody post-fire establishment and recovery to aid restoration efforts immediately post fire in a southern Californian shrubland. Specifically, we asked how do regeneration traits 1) differ from adult traits, 2) differ across aspect types, and 3) link to community recovery across aspect types. To answer these questions, we collected leaf functional traits for regenerating species within the Holy fire burn scar in the Cleveland National Forest and for adults in nearby unburned areas across northeast and southwest aspects. We then surveyed community composition within these different community types during the first year post fire.
Results/Conclusions
We found regeneration and adult traits to differ, where regeneration traits were indicative of resource-acquisitive growth strategies, highlighting the need to study regeneration traits vital to the recovery process. Regeneration traits did not differ across aspect type, but resprouters had traits indicative of the stress-tolerant growth strategy (ex. low Specific Leaf Area, SLA) and seeder species had traits of the resource-acquisitive growth strategy (high SLA) during the first year of recovery. This contrasts previous studies of adult traits where resprouting species typically utilize resource-acquisitive drought avoiding strategies while seeder species are thought to be more stress and drought tolerant. Looking at community traits weighted by species abundance, northeast aspects favored resource-acquisitive community functional strategies while southwest aspects favored stress-tolerant functional strategies - showing a tradeoff in community function due to aspect type. These community traits did not influence shrub recovery across aspect types. Our results highlight the difference in functional strategy for post-fire regeneration strategies is partially dependent on ontogenetic stage as well as environmental filters, like aspect type. Our work can help provide restoration managers with better predictive power for the conditions in which regeneration traits and local topographic environmental filters need to be considered in the recovery process.