Fire emissions and carbon uptake in lenga beech forests of Patagonia, Argentina.

BERTOLÍN, M. L. ; URRETAVIZCAYA, M. F.; DEFOSSÉ, G. E.

Fire Ecology

Association for Fire Ecology

Año: 2015 vol. 11 p. 32 - 54

1933-9747

Forest wildfires are recognized as sources of CO2 and other greenhouse  gases (GHG) that, altering the dynamics between terrestrial and atmospheric carbon (C) exchange, influence global climate. In central Andean Patagonia, Argentina, severe wildfires affect temperatelenga beech (Nothofagus pumilio) forests, thereby increasing atmospheric CO2 emissions and changing natural succession paths. In this study, we determined fire emissions and Cuptake in three lenga beech forests stands burned in 1976 (Lago Guacho site), 1983 (La Torta site), and 2008 (La Colisión site). Forest structure and aboveground biomass and litter compartments in burned and adjacent unburned stands were quantified for each fire. Carbon stocks and GHG (CO2, CO, CH4, NO2, NOx and Ce) released by the fires, CO2 removals, and mean annual C uptake were determined by following the International Panel of Climate Change guidelines. Total (aboveground plus root) C stock before fires was 301.8 Mg C ha-1 for La Colisión, 258.13 Mg C ha-1 for La Torta, and 270.7 Mg C ha-1 for Lago Guacho,while C losses due to the fires were 104.6 Mg C ha-1, 90.7 Mg C ha-1, and 94.7 Mg C ha-1 for the three sites,  respectively. Differences in pre-fire forest structures and biomass  explained the values observed in CO2 and other GHG emissions after the fires. Currently,the C balance is negative for the three sites. Without any active restoration and using actual growth rates for each site, the estimated C recovery time is 105.5 yr for La Colisión, 94.2 yr for La Torta, and 150.2 yr for Lago Guacho. By using variable rates of C uptake (which decrease as early succession proceeds), this recovery time will take 182 yr for La Colisión, 154 for La Torta, and 162 yr for Lago Guacho.  Post-fire environmental and site conditionsappeared to have a greater influence in forest recovery than primary fire effects. Active restoration activities may be necessary to increase C recovery rates and help to re-establish former lenga beech forest landscapes.