Survival and Recovery Following Wildfire in the Southern Range of the Coast Redwood Forest

摘要

Fire plays a central role in determining structure, composition, and recruitment in many forest types. In coast redwood forests, the role of fire is not well understood and scant literature exists on post-fire response, particularly in the southern part of the range. In order to better understand patterns of survival and recruitment following fire for coast redwood (Sequoia sempervirens [lamb. ex D. Don] Endl.) and associated tree species, three sites in the Santa Cruz Mountains, California, USA, were sampled following wildfire. Randomly selected 10 m diameter plots were used to collect data on survivorship and post fire regeneration in order to analyze short-term responses including mortality, crown retention, basal sprouting, canopy regeneration, and seedling production. Results indicated that coast redwood had the lowest percent mortality (11.98 %) and highest mean canopy retention (43.10 %) of all species sampled, followed by Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) (25.54 %), tanoak (Notholithocarpus densiflorus [Hook. & Arn.] Manos) (23.27 %), combined oak species (Quercus sp.) (6.67 %), and Pacific madrone (Arbutus menziesii Pursh) (4.13 %). In addition, associated species experienced higher survival rates when proximate to coast redwoods. Coast redwood trees also exhibited the highest canopy regeneration (53 %), the highest average density of basal sprouts (3.54 × 104 ha), and the greatest average number of seedlings, ranging from zero to 2.09 × 105 seedlings ha−1. Overall, coast redwood appeared to have a balance of fire adaptive features, exceeding all associated species, which allow individual trees to withstand fire, while at the same time promoting recruitment following fire.