Ecological Effects of Heather Burning: II. Effects on Seed Germination and Vegetative Regeneration

Publisher Website
Google Scholar
Abstract
In Calluna-dominated heathlands managed by periodic burning, vegetation composition is influenced by the ability of species to regenerate rapidly after a fire. Experiments were carried out, using a number of heathland species, to investigate the effects on germination of exposing seeds to short periods of heat treatment and to determine the influence of fire temperature on vegetative regeneration. In two species, Genista anglica and Hypericum pulchrum, evidence was obtained of stimulation of germination following short periods (30 s-2 min) of pre-treatment at 100.degree. C. There was some indication that in Vaccinium vitis-idaea a vernalization requirement might be over-ridden by a very short period of heating at 100.degree. C. Apart from these instances, there was little evidence of ''fire-adaptation'' of this kind. Treaments at 200.degree. C, or for more than 2 min at 100.degree. C, either killed seeds or reduced germination in most of the species tested. All tested species (except Juniperus communis) regenerated vegetatively after burning at 600.degree. C, but in most cases a temperature of 800.degree. C resulted in less recovery. These findings emphasize the importance of controlling management fires so that canopy temperatures are held within the range 400-600.degree. C and ground surface temperaturesrise little above 100.degree. C. These conditions should be sustained for no more than 2 min as the fire passes through the vegetation.