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Prescribed fire effects on early recruitment of Mediterranean pine species depend on fire exposure and seed provenance

Sagra, J., Moya, D., Plaza-Álvarez, P.A., Lucas-Borja, M.E., González-Romero, J., De las Heras, J., Alfaro-Sánchez, R., Ferrandis, P.
Forest ecology and management 2019 v.441 pp. 253-261
Pinus halepensis, Pinus nigra, Pinus pinaster, coniferous forests, fire prevention, forest management, fuel loading, fuels (fire ecology), geographical distribution, germination, habitats, natural regeneration, planning, prescribed burning, provenance, seeds, sowing, survival rate, wildfires
Prescribed fires are becoming more widely used forest management tool to reduce both fuel load for fire prevention and high-severity wildfires. However, alterations to site conditions and influence on the natural regeneration of these fires in Mediterranean pine forests are still poorly known. Our study investigates how using prescribed fires before or after natural pine seed release could influence changes in germination and individuals’ early survival by altering the composition and structure of these Mediterranean habitats. We ran a seed-sowing experiment to analyse the recruitment patterns of three Mediterranean pine species (Pinus halepensis, Pinus pinaster and Pinus nigra) in three sites where prescribed fires were carried out. In each site, we sowed one representative pine species according to natural habitats. Three treatments (control: sowing without intervention; pre-fire: sowing before prescribed fires; and post-fire: sowing after prescribed fires) were established. In the sown experiment, we tested two biogeographical seed provenances (wetter and drier regions) per species to observe different capabilities of adaptation. Germination and survival of individuals were monitored during one year. We observed that the provenances from drier areas had higher germination and survival rates than those from the wetter ones. The three species seemed to undergo a negative effect in the burned plots. Within the burned area, the pre-fire seeds presented higher germination and early survival rates than post-fire. These outcomes could be useful in fire management planning as a tool to influence forest regeneration.