High-severity wildfire effects on carbon stocks and emissions in fuels treated and untreated forest

Abstract

Forests contain the world's largest terrestrial carbonstocks, but in seasonally dry environments stock stability can be compromised if burned by wildfire, emitting carbon back to the atmosphere. Treatments to reduce wildfireseverity can reduce emissions, but with an immediate cost of reducing carbonstocks. In this study we examine the tradeoffs in carbonstock reduction and wildfireemissions in 19 fuels-treated and -untreatedforests burned in twelve wildfires. The fuels treatment, a commonly used thinning ‘from below’ and removal of activity fuels, removed an average of 50.3 Mg C ha^-1 or 34% of live tree carbonstocks. Wildfireemissions averaged 29.7 and 67.8 Mg C ha^-1 in fuelstreated and untreatedforests, respectively. The total carbon (fuels treatment plus wildfireemission) removed from treated sites was 119% of the carbon emitted from the untreated/burned sites. However, with only 3% tree survival following wildfire, untreatedforests averaged only 7.8 Mg C ha^-1 in live trees with an average quadratic mean tree diameter of 21 cm. In contrast, treatedforest averaged 100.5 Mg C ha^-1 with a live tree quadratic mean diameter of 44 cm. In untreatedforests 70% of the remaining total ecosystem carbon shifted to decomposing stocks after the wildfire, compared to 19% in the fuels-treatedforest. In wildfire burned forest, fuels treatments have a higher immediate carbon ‘cost’, but in the long-term may benefit from lower decomposition emissions and highercarbon storage.

Citation

North, Malcolm P.; Hurteau, Matthew D. 2011. High-severity wildfire effects on carbon stocks and emissions in fuels treated and untreated forest. Forest Ecology and Management. 261: 1115-1120.