Cattle affect early post-fire regeneration in a Nothofagus dombeyi-Austrocedrus chilensis forest in northern Patagonia, Argentina

MELISA BLACKHALL; ESTELA RAFFAELE; THOMAS T. VEBLEN

BIOLOGICAL CONSERVATION

Elsevier

Año: 2008 vol. 141 p. 2251 - 2261

0006-3207

In forest ecosystems where infrequent, severe fires have been an important process inshaping ecosystem structure, understanding the effects of introduced livestock on post-firerecovery of the vegetation is essential for effective forest resource management and preservation.In Nahuel Huapi National Park in northwestern Patagonia, we studied the effectsof livestock on the post-fire recovery of a Nothofagus dombeyi–Austrocedrus chilensis forestthat was burned in 1999.We experimentally excluded cattle by fencing plots and comparedthe vegetation characteristics of fenced and unfenced control plots over a 5-year period.Although cattle did not significantly reduce total plant cover or total species richness, theydid reduce maximum heights of woody species including the dominant tree species.Chusquea culeou, a tall understory bamboo, can impede establishment and height growthof the dominant tree species. Although C. culeou accounts for the largest percentage of cattlediet, its mean cover and mean maximum height were not strongly affected by cattle.The reduction in the height growth of seedlings of N. dombeyi and Austrocedrus in theunfenced areas implies that presence of cattle in the recently burned areas may contributeto a post-fire transition from tall forest to bamboo-dominated shrubland that is alreadywidespread in this landscape. Thus, these results provide support for the fencing ofrecently burned Nothofagus and Austrocedrus forests in the national parks for periods longenough to allow the dominant tree species to grow to heights at which they are no longerseverely inhibited by cattle browsing.