Post-fire regeneration of oak-pine forest across a chronosequence in western Mexico: key species for forest restoration

Abstract

Background: High-severity fires are serious anthropogenic threats to forests, as they can cause forest degradation on unrecoverable scales. Therefore, understanding the patterns and drivers of post-fire regeneration is essential to designing restoration proposals. Hypotheses: After a high-severity fire, we expected greater species richness and abundance of individuals in flat sites than in hillside sites since seeds, nutrients, and organic matter accumulate in flat landforms. Compared to some Pinus species, Quercus species are more drought-tolerant after a forest fire and, therefore, they are expected to dominate post-fire chronosequences. Study site: The study was conducted in the "La Primavera" Flora and Fauna Protection Area. Methods: We sampled vegetation and microenvironmental variables from 2021 to 2022 at 18 sites located on flat and hillside areas, at 3, 9, and ≥ 20 years since the last high-severity forest fires (TSF). Results: The richness of woody and herbaceous species was higher at 3 TSF and 9 TSF. The topographic condition did not significantly drive the richness and abundance of woody species, but richness and abundance of herbaceous species were significantly greater in flat sites. The oak tree Quercus resinosa Liebm. was the dominant species throughout the chronosequence. Conclusions: Quercus resinosa represents a foundational species for recovering forest structure and composition. Flat sites may act as regeneration nuclei, but hillside sites require greater restoration efforts.