Role of fire on patagonian grasslands: Changes in aboveground vegetation and soil seed bank

Abstract

Grasslands are ecosystems dominated by herbaceous and woody vegetation, whose structure is determined by fire, grazing, and drought. Although these structuring factors determine the natural dynamics of grasslands, their plant biodiversity can be affected when these disturbances occur in an extreme or unbalanced way. The Argentinean northwestern Patagonia grasslands are fire-prone ecosystems, and fire events have relevant implications on the vegetation recovery. In this chapter we will focus on the postfire dynamics of aboveground vegetation and seed bank. The results indicate that grasslands are resilient to fire, evidencing a fast vegetation recovery. Fire promotes recruitment opportunities to native shrubs and fugitive species. Some of these species come from the seed bank increasing the aboveground vegetation biodiversity. Fires also contribute to spread exotic species that have already invaded Patagonian grasslands. Therefore fire has multiple effects on grassland dynamics, but more long-term studies are necessary in order to propose management guidelines for the sustainable use of these ecosystems in ways compatible with biodiversity conservation. In addition, with global climate change, an increase of El Niño Southern Oscillation (ENSO) frequency and amplitude is expected. Considering that the wildfires regime is affected by ENSO, it is important to find the relationships between this phenomenon, fire and vegetation patterns. Several relevant questions arise in relation to the future of grasslands as important suppliers of goods and services, and as irreplaceable biodiversity source.