Climate change could reduce US forest stocks by a fifth this century – ScienceDaily

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A study by a researcher at North Carolina State University found that under more severe climate warming scenarios, the stock of trees used for timber in the continental US could decline by up to 23% by 2100. The largest stock losses will occur in two of the leading timber regions In the United States, both in the South.

The researchers say their findings show modest effects on the price of forest products through the end of the century, but point to larger impacts in terms of carbon storage in US forests. Two-thirds of the United States’ forests are classified as woodlands.

said lead author of the study Justin Becker, associate professor in the Department of Forestry and Resources Environment at North Carolina State University. “This is a dramatic change in the permanent forest.”

In the study published in Forest policy and economics, the researchers used computer modeling to project how 94 individual tree species would grow in the continental United States under six warming scenarios to the year 2100. They also looked at the impact of two different economic scenarios on the growth in demand for forest products. The researchers compared their findings on forest inventories, harvests, prices, and carbon sequestration with scenarios without climate change. The researchers said their methods could provide a more accurate picture of the future forest sector under high-impact climate change scenarios than other models.

“Many of the previous studies show a very optimistic picture of forests under climate change because they see a significant increase in forest growth from the extra carbon dioxide in the atmosphere,” Baker said. “The effect of carbon dioxide on photosynthesis in some of these models tends to outweigh the losses you see from precipitation and temperature-induced changes in forest productivity and tree death. We have a model specific to individual tree species, and this allows us to better understand how climate factors influence on growth and mortality rates.

Researchers have found that in certain areas trees grow more slowly in higher temperatures, and die faster. Combined with increasing harvest levels and increasing development pressures, this has resulted in a decline in the total tree stock. They expected the largest losses to be in the Southeast and South Central regions, two of the three most wood-producing regions in the United States. baseline scenarios. Because of the decline in pine products, the researchers predicted that softwood prices could increase by up to 32% by 2050.

“We found very high levels of sensitivity to changes in global warming and precipitation for southern-producing pine species, especially when climate change is combined with higher demand for forest products,” Baker said.

However, the researchers expected gains in tree supply in the Rocky Mountains and Pacific Southwest regions, driven by high rates of death of some trees that lead to larger crops initially, followed by the growth of more heat-tolerant species.

“These are areas that are losing a lot of stock right now because of pests and fire disturbance,” Baker said. “What you’re seeing is a higher level of replacement with climate-adapted species like junipers, which are more tolerant of future growing conditions.”

Incorporating impacts from all regions, the researchers projected total tree stock losses in the US from 3 to 23% compared to baseline. They projected losses in carbon sequestration in most scenarios, and estimated the value of lost carbon stored in US forests at up to $5.5 billion annually.

They found that the economic impact of climate change on the overall value of the US forest products industry could range from a loss of up to $2.6 billion annually — representing 2.5% of the industry’s value — to an increase in value of more than $200 million a year.

“We’ve seen that markets can be more resilient than the forests themselves,” Baker said. “Your market impacts may seem modest in terms of their impact on consumers and producers, but these impacts are small compared to the carbon sequestration value that forests provide on an annual basis.”

Researchers say more studies are needed to shed light on the future of forests in the United States.

“We don’t know much about how deaths associated with disturbance or loss will affect tree productivity across landscapes as temperatures rise,” Baker said. “We’ve done our best to address two pieces of the puzzle with changes in temperature and precipitation, and the interactions between climate and market demand, but there is a lot of work to be done to get a good handle on climate change and forests.”

The study, “Projecting US Forest Service, Market, and Carbon Sequestration Responses to a High-Impact Climate Scenario” is published online in Forest policy and economics. Co-authors included George van Houteven, Jennifer Phelan, Gregory Latta, Christopher M. Clarke, Kemen Austin, Olakunle Sodia, Sarah B. Orell, John Buckley, Lauren E. Gentile, and Jeremy Martinich. The study was funded by the US Environmental Protection Agency under Contract No. 68HERH19D0030. The views and opinions expressed in this paper are those of the authors alone and do not necessarily imply or reflect the views of the EPA, and no official endorsement should be inferred.

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