Non linear ecological processes, fires, environmental heterogeneity and shrubs invasion in NW Patagonia, Argentina

GHERMANDI, L.; FRANZESE J.; GONZALEZ S.; DE TORRES CURTH M.

Viena, Austria

Congreso; European Geoscience Union, General Assembly 2008; 2008

The emergent nature behaviour is not only the sum of interactions among ecosystem parts but it depends on the organization of these interactions.Fire behaviour, climate and vegetation patterns produce non linear fire propagation across landscape. Fire can increase the abundance of determined species modifying the fire regime and increasing the invasion of the same species (Eg.: Fabiana imbricata and Senecio bracteolatus shrubs in NW Patagonia). Environmental heterogeneity like outcrop presence favours landscape patchiness with different fire frequency and it generates the occupation of fire refuges by species that can survive there (Eg: Autrocedrus chilensis tree). We monitored shrubs cover and recruitment during 8 postfire years in NW Patagonia grasslands. We described shrub population dynamics with matrix models projecting the population in hypothetical scenarios of different fire and ENSO (El Niño Southern Oscillation) frequencies.Fire promote shrubs invasion in NW Patagonia. Global climate chance suggests the increase of frequency and amplitude of ENSO phenomena, which in NW Patagonia signify more coupled fires and rainy springs, and consequently more shrub windows of recruitment. The matrix models indicate that this scenario promote shrubs invasion.Future analysis of satellite imagines and aerial photographs will provide information about long term changes in vegetation and fire regime. Our results increase the knowledge of ecosystem properties and processes providing useful information to improve the grasslands sustainable use.