Key factors influencing post-fire vegetation recovery in Pinus halepensis forests: divergent effects for canopy and shrub species

Abstract

Aims

Rapid revegetation of burnt forest is essential for recovering ecosystem functioning, especially in the context of climate change–driven shifts in fire regime. This study aimed to provide a comprehensive understanding of how abiotic factors (topography, fire behaviour) and biotic factors (pre-fire forest characteristics, plant reproductive strategies, land-use trajectories) influence the recovery of Pinus halepensis forests, identifying regeneration vulnerabilities that could inform management practices. Location

A P. halepensis forest burnt in 2019 (4000 ha) in NE Iberian Peninsula. Methods

We established 72 sampling sites within the burnt forest, covering gradients of pre-fire canopy cover (PCC), topography, fire severity and land-use history. At each site, we recorded the abundance of P. halepensis seedlings within a 100-m2 plot. We also conducted a floristic inventory of all associated woody species along two parallel 20-m transects to assess woody species cover, richness and distribution. Woody species were classified based on their post-fire reproductive strategies (obligate seeding, facultative resprouting and resprouting) to explore the relationship between functional characteristics and plant distribution along the studied gradients. Results

Northern exposures enhanced the abundance of P. halepensis, whereas coexisting woody species cover was higher on southern ones, probably due to the contribution of obligate seeders, as fire-responsive reproductive traits vary along the north–south gradient. PCC boosted pine regeneration and species richness, while high fire severity reduced both cover and richness of woody species, likely due to damage to reproductive structures. Conclusions

We show that the drivers of post-fire regeneration influence in different and even divergent ways the vegetation components considered (canopy and shrub layer), as in the case of aspect. From a management perspective, post-fire forest interventions should be tailored to restoration objectives and to the post-fire vegetation communities that better respond to them.

This study was funded by the projects VULNIFOR (PID2022-142108OB-I00) and LLEGATS (CNS2023-145351) from the Spanish Ministry of Science and Innovation. The research was conducted under the frame of the ADAPTAFOR research group (2021-SGR- 01530), funded by the Catalan Agency for Management of University and Research Grants. M.P. received funding from the European Union's H2020 research and innovation programme under Marie Sklodowska- Curie grant agreement No. 801586. A.A. is a Serra-Húnter fellow from the Generalitat de Catalunya.