Fire temperatures and postfire plant community dynamics in Ecuadorian grass páramo

Abstract:

Three aspects of the páramo vegetation's response to fires were investigated: the measurement of fire temperatures, general observations of changes in plant communities following fires, and monitoring the fate of individual plants after burning. Fire temperatures were strongly influenced by the physiognomy of the vegetation, dominated by tussocks of Calamagrostis spp. Temperatures were highest amongst the upper leaves of the tussock (sometimes >500°C). The middle levels of the tussock experienced temperatures in excess of 400°C, but in the dense leaf bases temperatures were often below 65°C. On the ground between tussocks, temperatures were variable, whereas 2 cm below ground temperatures failed to reach 65°C. Plant survival depended on the intensity of the fire and the plant's position within the tussock structure. Survival was often the result of high temperature avoidance (with buds shielded by other plant parts or buried beneath the soil surface). Post-fire Calamagrostis tiller mortality rates were high and tussock regrowth was slow. Some other species appear to maintain their populations by exploiting this recovery phase for seedling establishment on tussocks. Between tussocks, changes of occupancy at the level of the individual plants were greater after fire than in control vegetation. Most transitions were random. Those which departed from random often involved gaps and were related to post-fire mortality, regrowth from below-ground parts, colonisation or, in the case of a clonal mat-forming species, to spatial rearrangement of rosettes. Recovery was slower at higher altitude. Recovery was much slower in burned plots when the upper 2 cm of soil was removed (along with buried plant parts) compared with burned plots. Qualitative observations suggest that recovery may consist of a cyclical process, mediated by the serial dominance of several species that are physiognomically important. The frequency of fires determines the amount of fuel accumulated within grass tussocks and some plants may be unable to survive repeated burning. Chance survival of species in unburned patches of vegetation and random colonisation of gaps may be important determinants of subsequent community structure. © 1996 Kluwer Academic Publishers. Printed in Belgium.

Año de publicación:

1996

Keywords:

• Succession
• ECUADOR
• tropical alpine
• burning
• vegetation dynamics

Fuente:

scopus