Optimizing Forest Management Stabilizes Carbon Under Projected Climate and Wildfires

Abstract

Forests provide a broad set of ecosystem services, including climate regulation. Other ecosystem services can be ecosystem dependent and are in part regulated by local‐scale decision‐making. In the southwestern United States, ongoing climate change is exacerbating a legacy of fire‐exclusion that has altered forest structure and increased high‐severity wildfire risk. Management can mitigate this risk by reducing forest density and restoring frequent surface fires, but at the cost of reduced carbon stocks. We sought to quantify the role of management in building adaptive capacity to projected climate and wildfires and the carbon consequences in a forested watershed. We simulated carbon dynamics under projected climate and wildfires and two management scenarios: prioritized and optimized. The prioritized scenario involved thinning and prescribed burning in areas selected by stakeholders to mitigate high‐severity wildfire risk. The optimized scenario used the probability of high‐severity wildfires to locate thinning treatments and increased prescribed fire area burned relative to the prioritized scenario. Both scenarios reduced wildfire severity and significantly increased net photosynthesis relative to no‐management. However, the optimized scenario decreased management‐related losses by 2.4 Mg • C • ha−1 and wildfire emissions by 2.9 Mg • C • ha−1 relative to the prioritized scenario. By decreasing the area thinned and increasing the area burned relative to the prioritized scenario, the optimized scenario halved the time to realize a net carbon benefit relative to no‐management. Given the increasing climatic and disturbance pressures impacting southwestern forests, management will play a critical role in building adaptive capacity and ensuring the continued provision of ecosystem services.

Commentary: Large Trees Dominate Carbon Storage in Forests East of the Cascade Crest in the United States Pacific Northwest

“…Mildrexler et al contains no analysis of changes in carbon stocks over time, despite current and projected increases in climate change-driven drought and wildfire (Halofsky et al, 2020;Parks and Abatzoglou, 2020). Other studies of dry forest ecosystems that incorporate disturbance-mediated mortality conclude that management strategies informed by historical conditions stabilize carbon stocks given projected climate change (Liang et al, 2018;Hurteau et al, 2019;Krofcheck et al, 2019;McCauley et al, 2019).…”

“…In particular, the number of shade-tolerant fir ≥53 cm DBH increased substantially over the last century as a consequence of fire exclusion (Hagmann et al, 2013(Hagmann et al, , 2014Merschel et al, 2014;Johnston, 2017;Johnston et al, 2018). Mildrexler et al ignore research showing that dry forests have overshot their carbon-carrying capacity and that thinning treatments, although they reduce carbon stocks in the short term, will tend to stabilize carbon stocks over multi-decadal time scales in the face of a warming climate (e.g., Hurteau et al, 2019;Krofcheck et al, 2019). Mildrexler et al assert without evidence that large shade-tolerant fir are not overrepresented on the landscape and that forests of eastern Oregon have "low future climatic vulnerability."…”

Modeling Subtropical Forest Changes under Climate Change and Close-to-Nature Silviculture: Is There a Tipping Point in an Uncertain Future in Southern China?

“…They found that disturbance may drive the range expansion of broad-leaved species, and conifers were favored for pulp production. In addition, other previous studies focused on the effect of, for example, fire and harvesting [17,18], forest carbon management [19], and forest ecosystem services [20]. Forest landscape simulations are helpful for understanding the effect of climate and harvesting on forest AGB, and to formulate corresponding forest management strategies in advance.…”

Forest Thinning in Ponderosa Pines Increases Carbon Use Efficiency and Energy Flow From Primary Producers to Primary Consumers

“…Stand T-15 was thinned in 2015. We do not show stand T-17 in the image because the Google maps image was from prior to 2017 and does not show the thinning in T-17. in the short-term, but protect and stabilize long-term storage in live large trees (Krofcheck et al, 2019;Sorensen et al, 2011). There have been fewer studies of respiration and belowground components.…”

“…Modeling studies suggest that thinning and associated prescribed burning treatments in ponderosa pine forests reduce carbon storage DOUGHTY ET AL. in the short-term, but protect and stabilize long-term storage in live large trees (Krofcheck et al, 2019;Sorensen et al, 2011). There have been fewer studies of respiration and belowground components.…”