Year: 2017
Type: article
Abstract: Amazon droughts directly increase forest flammability by reducing forest understory air and fuel moisture. Droughts also increase forest flammability indirectly by decreasing soil moisture, triggering leaf shedding, branch loss, and tree mortality—all of which contribute to increased fuel loads. These direct and indirect effects can cause widespread forest fires that reduce forest carbon stocks in the Amazon, with potentially important consequences for the global carbon cycle. These processes are expected to become more widespread, common, and intense as global climate changes, yet the mechanisms linking droughts, wildfires, and associated changes in carbon stocks remain poorly understood. Here, we expanded the capabilities of a dynamic forest carbon model to better represent (1) drought effects on carbon and fuel dynamics and (2) understory fire behavior and severity. We used the refined model to quantify changes in Pan-Amazon live carbon stocks as a function of the maximum climatological water deficit (MCWD) and fire intensity, under both historical and future climate conditions. We found that the 2005 and 2010 droughts increased potential fire intensity by 226 kW m −1 and 494 kW m −1 , respectively. These increases were due primarily to increased understory dryness (109 kW m −1 in 2005; 124 kW m −1 in 2010) and altered forest structure (117 kW m −1 in 2005; 370 kW m −1 in 2010) effects. Combined, these historic droughts drove total simulated reductions in live carbon stocks of 0.016 (2005) and 0.027 (2010) PgC across the Amazon Basin. Projected increases in future fire intensity increased simulated carbon losses by up to 90% per unit area burned, compared with modern climate. Increased air temperature was the primary driver of changes in simulated future fire intensity, while reduced precipitation was secondary, particularly in the eastern portion of the Basin. Our results show that fire-drought interactions strongly affect live carbon stocks and that future climate change, combined with the synergistic effects of drought on forest flammability, may strongly influence the stability of tropical forests in the future.
Source: Environmental Research Letters
Language: English
Topic: Fire effects on ecosystems
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: gold
Estimated APC paid: $3,045
Awards: Amazon forest response to droughts, fire, and land use: a multi-scale approach to forest dieback, THE RECENT EXPANSION OF PASTURES AND AGRICULTURAL MONOCULTURES HAS RESULTED IN 730,000 KM2 OF THE AMAZON BASIN BEING DEFORESTED. DESPITE RECENT DECLI, THE ANNUAL FLOOD OF THE AMAZON RIVER IS THE WORLD S LARGEST INUNDATION EVENT, FLOODING ABOUT 300,000 KM^2 FOR SIX OR MORE MONTHS EACH YEAR, WITH WATE, G6732530175, G7418193128
OpenAlex ID: W2603761176