FIA Data Inform Studies on Land Use Conversions, Markets, and More

Strong forest markets protect forests by reducing conversion of forests to other land uses, according to a recent study. The study uses data from the Forest Inventory and Analysis program.

forest land
The amount of forested land was stable across the survey cycle – 97 percent of forested land remained forested. Photo by Linda Haugen, USDA Forest Service, Bugwood.org.

“Across the Southeast and the rest of the U.S., FIA provides detailed observations of every aspect of the forest resource,” says John Coulston, a USDA Forest Service supervisory research forester.

Coulston and retired SRS research forester David Wear devised a study on forest land use responses to wood product markets. The study was published in the journal Forest Policy and Economics. Taek Joo Kim, an ORISE post-doctoral researcher, conducted the study.

With FIA data, the team could incorporate detailed measures of forest attributes, including 10-15 years of recent land use and land use conversions, market data, and management options.

“Our study differs from previous land use models in how timber quasi-rents are calculated,” says Coulston. “We based timber quasi-rents on the current merchandized value of timber versus the expected discounted value.”

The scientists calculated timber quasi-rents at FIA plots across the southeastern U.S. The calculations were the basis for comparing forest management and land use choices to other landowner options.

Of the 25 possible land use transitions Coulston and his colleagues identified, forest was the most stable across the cycle. The most common transitions occurred between crop and pasture land use.

“Ninety-seven percent of forest remained forest,” says Coulston. “Forest remained the largest land use in the Southeast.”

The study area spanned the southeastern U.S., including eastern Texas and Oklahoma. Throughout the region, large metropolitan areas are growing quickly, while many rural areas are experiencing depopulation.

The area of developed land increased over the study period, as did the area of forested land. In some parts of the Southeast, sawmills are distant, or markets are non-existent. But other markets, such as wood pellet mills, are growing.

High timber quasi-rents reduce conversions of forests to other land uses.

“The future of forest product markets in the southeastern U.S. is likely to have important influences on the area of forest land use,” says Coulston.

Higher demand for woody biomass as a bioenergy feedstock would prevent forest land conversion to other uses and could even lead to a 12 million acre increase in timberland in the Southeast, as a separate study shows.

Eighty-two percent of southern plantation forests are located in the Coastal Plain, as the Southern Forest Futures Project documented. USFS photo, Bugwood.org.

Between 2012 and 2017, southern wood pellet exports grew by approximately 180 percent, as SRS scientists Consuelo Brandeis and Karen Abt show in a study published in the Journal of Forestry.

Using mill-level data collected by FIA, the scientists show that the volume of roundwood (small logs) used for pellet production has increased and represents almost two percent of all southern timber products output.

Forest biomass is closely linked with forest carbon, a subject of great interest to policymakers interested in mitigating climate change by sequestering carbon in forests. To project the amount of carbon stored in forests, scientists use modified forest sector models.

FIA data are the empirical basis for most US forest carbon projection models as Coulston and Wear note in a recent paper published in the Journal of Forest Economics.

However, most contemporary forest carbon projections models fail to leverage the full power of the annual FIA inventory and observed forest transitions because the analytical basis for these models was developed in the 1970s when forest inventory data were scarce and inconsistent.

Today, FIA data are consistent, through space and time, across the nation. Also, the equations, methods, and some data are publicly available. For example, Thomas Brandeis and his colleagues document the FIA approach for estimating site class and site index. They discuss these two methods of estimating site quality in a recent Research Note.

FIA’s repeated measurements of forest dynamics can be used to validate and inform a wide range of models. “Current forest inventories are a strong empirical foundation for Forest Inventory Projection Models and many others,” says Coulston.

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For more information, email John Coulston at john.coulston@usda.gov, Conseulo Brandeis at consuelo.brandeis@usda.gov, or Thomas Brandeis at thomas.j.brandeis@usda.gov.

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