Simulation of Crown Fire Effects on Canopy Seed Bank in Lodgepole Pine

Abstract

Analysis of video footage taken of crown fires during the 1988 fire season in Yellowstone National Park indicated that the most frequent length of time required to completely burn tree crowns was 15-20 seconds. Lodge-pole pine (Pinus contorta Laws.) seeds were tested for ability to germinate after exposing both serotinous and nonserotinous cones for 10 to 60 seconds in a flame front designed to simulate a crown fire. Heating enhanced germination of seeds from serotinous cones but not those from nonserotinous cones. Maximum germination rates for serotinous cone seeds ranged from 37 to 64 percent and occurred after 10-20 seconds exposure of cones to flames. Germination after 60 seconds exposure averaged 0.3 to 14 percent. Maximum germination of seeds from nonserotinous cones (about 80%) occurred with no exposure and after 10 seconds in the flames.

Assessment of crown fire initiation and spread models in Mediterranean conifer forests by using data from field and laboratory experiments

“…Moreover, both in the field and bench experiments, thermocouples records supplied values for flaming residence time in different conditions of heat transfer and assuming a common ignition threshold (573 ºK). The measured time were quite similar among them, consistent with data referred by Despain et al (1996), obtained from video records in the Yellowstone fire (1988) and those measured in the above referred crown fire experiments.…”

Effect of high temperatures on cone opening and on the release and viability of Pinus pinaster and P. radiata seeds in NW Spain

“…The former also requires exposure times of above 10 minutes at 100 ºC and above 1 minute at 332 O. Reyes and M. Casal The level of cone protection against heat varies from one species to another. Beaufait [4] found that P. banksiana protected its seeds until cone ignition and Despain et al [9] found that in P. contorta, 88% of seeds remained viable after being exposed to 480 ºC for 30 seconds. Furthermore, Judd [14] suggests that insulation capacity depends on cone size and whether or not the fruit or cone contains internal divisions that increase its insulation capacity.…”

“…Surface fires do not usually affect the opening of pinecones since the crowns are not sufficiently heated. However, in crown fires flames can sometimes reach temperatures close to 1000 ºC in a short space of time [9], which leads to cone combustion. The role of fire in the opening of cones and seed dispersal has been studied in some Pinus species [4, 9, 10, 16-18, 24, 27, 32].…”

Disturbance interactions can impact resilience mechanisms of forests

“…4). High severity fire alone does not typically consume serotinous cones in tree crowns (Despain et al 1996) and the lack of deep soil charring (for example, ,14 mm in the highest burn class surveyed post-1988 Yellowstone fires, Turner et al 1999) indicates low duration burns (Neary 1999). The weaker increase in modeled maximum temperature (Fig.…”

“…In a typical subalpine crown fire, fire is sustained in an individual tree canopy for 20-30 seconds (Despain et al 1996), enough to trigger seed release from the serotinous cones. An increase in fire residence time or absolute temperature can consume cones and seeds, and has been an observed cause for lack of regeneration under burned slash piles (Lotan and Perry 1983 and references therein).…”