Fire-related cues improve germination and seedling vigor of the post-fire off-spring of Pinus radiata, a serotinous invader tree

RIPA R.; FRANZESE J.; PREMOLI A.; RAFFAELE E.

NEW FORESTS

SPRINGER

Lugar: Berlin; Año: 2022

0169-4286

Germination rate and seedling establishment control post-fire regeneration of trees andmay foster invasion of exotic species particularly of fire-adapted species as theserotinous Pinus radiata. We analyzed the influence of heat shock and the presenceof ash as substrate on seed germination and early vigor of seedlings of distinct cohortsof P. radiata that developed under the influence of fire or in the absence of it, i.e. postfireinvasion and unburned plantation, respectively. Seeds were collected from theReserva Forestal Lago Epuyén in Northern Patagonia, Argentina. The natural history ofthis region is characterized by the occurrence of extensive fires. Ten randomlyselected trees from unburned plantations and post-fire invasion that occurred in 1987of similar age were cut down and 10 serotinous cones by plant were collected withoutcolor or size bias. Seeds from both stand types were subjected to four treatments: ashsolution (5 g/L) and two thermal shocks (90 and 120 °C for 5 minutes), and a controlwithout thermal shock or ash presence. The number of germinated seeds was countedevery 5 days during 30 days. Germination percentages observed were high (between80% and 100%) for both seed sources and under all the fire-associated treatments.Post-fire invasion had longer radicles with ash and under the thermal shock at 90°C, aswell as a higher percentage of seedlings that developed cotyledons and with thehighest survival. Recurrent fires exert a significant effect on germination and earlygrowth of the exotic P. radiata which may foster invasion.