Postfire growth of two dominant tussock grasses in northwestern patagonian grasslands

GONZALEZ SOFÍA; GHERMANDI LUCIANA; PELÁEZ DANIEL

S.C. de Bariloche

Congreso; VI Southern Connection Congress; 2010

Postfire growth of two dominant tussock grasses in northwestern Patagonia grasslands Gonzalez, S., Ghermandi, L., Peláez, D. Fire affects plant survival and growth. Our aim was to evaluate the fire effect on growth of two native tussock grasses, Festuca pallescens (very palatable) and Stipa speciosa (unpalatable). In May 2008, plants of each species were exposed to low temperature (200-400ºC), high temperature (500-700ºC) and no fire (control) (n=9 per treatment and per species: 54 plants in total). We removed the biomass before all the treatments (included control), and we burned plants with a portable burner device. From September 2008 to March2009, we monitored the length of six tillers per plant of each treatment. We registered low mortality after fire, 2% in F. pallescens, and 0% in S. speciosa in both temperature treatments. F. pallescens resprout length was higher in control treatment than in temperature treatments while S. speciosa tiller growth was similar between fire and control treatments in October and November monitoring dates. Comparing between species, the S. speciosa tiller growth was higher than in F. pallescens (only in low temperature treatment). We concluded that fire is relevant in determining the resprout growth of both species during the first postfire growth season. A low intensity fire would benefit the S. speciosa growth compared to F. pallescens, affecting their population dynamics. Moreover, being S. speciosa unpalatable species rarely consumed by livestock, also the productivity of grasslands would be affected.