congresos y reuniones científicas
Plant traits and plant successional pathways modulate landscape-level vulnerability to changes in fire ignition frequency: a simulation modeling approach
Punta Arenas
Congreso; VIII Southern Connection Congress; 2016
Ecosystems differ widely in their impacts to human-induced changes in fire regimes, yet the ecological mechanisms conferring resilience/vulnerability are still unclear. Plant functional attributes and successional patterns can help generalize patterns of landscape resilience to fire. We simulated fire spread and vegetation responses by randomly igniting artificial landscapes with increasing ignition frequencies. Landscapes were composed by: 1.a single community with long-lasting dominance obligate seed dispersed (R-) which with time since fire densifies and creates fuel ladders, 2. a single communities with post fire stages dominated by R- which during mature stages canopies inhibit understorey growth and/or produce moist microenvironments, 3. a single community dominated by resprouters (R+) throughout the post fire succession and, 4. early stage communities with codominace of R+ and R- (pyrophytic community) and mature stages where R- overgrows and competitively inhibits R+ (pyrophobic community). After simulations we quantified fire size distributions, proportion and spatial persistence of mature/young stages or pyrophitic/pyrophytic communities. We found that landscape types 1 and 3 with dominance of R- and R+, respectively and where flammability increases asymptotically with time since fire had linear responses in the proportion of mature/young patches to changes in ignition frequency, thus suggesting relative resilience to changes in ignitions. In contrast, landscapes types 2 and 4 where flammability declines during mature stages displayed alternative stable states (young/matures or pyrophytic/ pyrophobic states, respectively) and critical ignition frequency thresholds beyond which landscapes show abrupt fire regime and community shifts.