Germination responses to experimental burns of two dominant perennial grasses in NW Patagonia grasslands (Argentina)

FRANZESE JORGELINA; GHERMANDI LUCIANA

Congreso; VI Southern Connection Congress; 2010

Semi-arid grasslands of NW Patagonia are subject to frequent fires. They can impact on the regeneration of native plant species in different ways. The aim of this work was to study the effect of fire on seed germination of the dominant perennial tussock grasses: Stipa speciosa and Festuca pallescens. In field we sowed ten 50 cm diameter plots per species with 50 seeds each. In May 2009, we burned half of the plots per species (Burned treatment), whereas we left the remaining plots as controls (Unburned treatment). There was germination in all plots. The experimental burning inhibited Festuca germination (Burned = 26 % vs Unburned = 41 %), whereas it promoted Stipa germination (Burned = 32 % vs Unburned = 16 %). These results support other ones obtained in lab conditions.  The structures which wrap the seeds of Festuca seem to be thinner than the ones of Stipa. As a consequence, Festuca seeds could have had a poor protection of heat. The promotion of germination in Stipa could have been due to the presence of smoke during the burnings since this factor improved their germination in lab experiments. Then, fire occurrence seems to favor Stipa regeneration, and it could have important economic implications since it is an unpalable plant.