Producción y germinación de bellotas del roble andino Quercus humboldtii (Fagaceae) afectado por incendios recurrentes

Introduction: Anthropogenic disturbances, including wildfires, threaten the diversity of tropical Andean ecosystems. Consequently, 60-90 % of Colombian pre-Hispanic oaks have disappeared. Andean oak forests are
dominated by Quercus humboldtii, the only South American species of Fagaceae which has high socioeconomic
and biodiversity interests. The reproductive response of this species will condition its regeneration capacity and
the persistence of oak forest. However, our knowledge about the effect of fire on this response is incipient.
Objective: To evaluate the production and germination of Q. humboldtii acorns in oak forests affected by recurring wildfires.
Methods: We monitored the production and germination of acorns from Q. humboldtii trees in fire and nonfire affected forests in the Eastern Andes of Colombia, Boyacá, Serranía de Iguaque, during 14 months. We also
evaluated fire incidence, tree size, precipitation, temperature, and other site characteristics.
Results: Acorn production began 34 months after the fire. In burned oaks, the production of incompletely
developed acorns (abortions) was almost nine times higher than viable acorns, and those with larger scar areas or
many scars were more likely to produce abortions. Conversely, oaks of larger size, especially at the crown, tended
to produce more acorns. The few viable acorns from fire-affected trees had smaller sizes and lower germination
rates compared to those documented for unburned trees in existing literature. The unburned trees did not produce mature acorns, but abortion production was ten times lower than in the burned trees. Therefore, it is feasible
that Q. humboldtii presents masting, and the unburned trees are in a low production cycle.
Conclusions: Fire, tree size, and masting drive acorn production in the Iguaque oak forests. These could affect
the recruitment of the species due to a possible limitation in the source.