Are forest management plans for carbon storage compatible with those for timber harvest and wildlife habitat?

By: Laurie Houston

Forest
Old growth forest Mt. Hood Oregon. Researchers at OSU and the U.S. Forest Service Pacific Northwest Research Station have developed a method for assessing tradeoffs among management scenarios with varying emphasis on carbon storage, timber production and habitat for focal wildlife species. Photo Credit: US Forest Service

Since 1960, the U.S. Forest Service has managed national forests for multiple uses including timber production, water supply, recreation, and fish and wildlife.  Added now to that portfolio of management objectives is carbon storage to help mitigate climate change. However managing for multiple uses is extremely complex, because management that favors one use may not always simultaneously favor other uses. Forest management effects on carbon storage generally are known: older trees store more carbon than younger trees; harvesting trees decreases the volume of carbon stored on the landscape; the amount of carbon being stored increases more rapidly in young forest than in older ones. However, how management intended to increase stored carbon might influence other ecosystem services has been somewhat uncertain. So how do you design forest management plans that address carbon storage while also continuing to provide other desired goods and services?

My colleagues at the Pacific Northwest Research Station and Oregon State University (Kline et al. 2017) have examined these challenges. They identified the possible outcomes (e.g., carbon, timber, habitat) of different management regimes for a western Cascades forest landscape, to determine which management objectives might be in conflict with one another and which might be complementary. The intent was to (1) characterize the general production relationships for combinations of carbon storage, timber, and habitat, and (2) identify management variables that most influence the compatibility of these outcomes.

The scientists used simulation models to estimate landscape-level stored carbon, timber harvest, and habitat for seven focal wildlife species across an array of management regimes. The range of possible management regimes examined provided a near comprehensive view of carbon storage, timber, and habitat possibilities available across this region. Their results show the potential trade-offs associated with managing these forests to store carbon and how these trade-offs are influenced by management variables and ecological conditions. By systematically examining a broad range of management regimes—from no harvest to intensive timber utilization and from short to very long rotations—the researchers were able to identify management policies that ranged from complementary to competitive.

Male bluebird on stick
Male western bluebird. (USFS photo)
Fly catcher bird on log
Olive-sided fly catcher- alan schmie‪rer
Owl
Northern spotted owl bureau of land management

Maximizing carbon storage by reducing timber harvests and maintaining mature forest conditions can be complementary to creating habitat for Northern Spotted Owl and Olive-sided   Flycatcher. Bluebirds prefer young forests making management for bluebirds competitive with management for carbon and Spotted Owls. Photo Credits: Flycatcher- Alan Schmierer, Spotted Owl – Bureau of Land Management, Western Bluebird – US Forest Service

The study revealed that carbon-habitat relationships vary depending on disturbance (or harvest) interval and that management focused on storing carbon could result in complementary, competitive, or neutral tradeoffs among the seven wildlife species examined. These species included Western Bluebird, Pileated Woodpecker, Olive-sided Flycatcher, Mule Deer, Pacific Martin, Red Tree Vole, and Northern Spotted Owl, and represent a variety of possible forest ecosystems within the western Cascades forests. The study found that maximizing carbon storage by reducing timber harvests and maintaining mature forest conditions, can be complementary to creating habitat for Northern Spotted Owl and Olive-sided Flycatcher, both of which favor close-canopy conditions and some older forest. However, these management regimes cannot be established across the whole region because they conflict with the goal of providing habitat for other key species such as the Western Bluebird which favors more open forest conditions created by more frequent disturbance.

The relationships between production possibilities of carbon, timber, and habitat identified in this study allow for a landscape-level approach for informing management decisions. This approach allows for variation in management strategies across the landscape that can reflect specific species needs. The tradeoff management framework developed in this research, will allow land managers a better understanding of the multiple ecosystem services a management plan may provide. This framework also helps to define long-term potentials for managing forests to produce carbon, timber, and habitat across multiple ownerships. Such information allows stakeholders to test prevailing assumptions about the degree to which various ecosystem services can be produced in combination with each other. 

So can managing for carbon storage be compatible with wildlife habitat and timber harvest? The short answer is yes. However, it requires using a variety of management approaches, including a mix of short and long rotations, to address a variety of competing habitat requirements. So there may not be one “sweet spot” that balances all three sets of objectives. But there are an array of alternatives with different trade-offs. Managing western Cascades forests to store carbon can be roughly complementary with habitat for Northern Spotted Owl, Olive-sided Flycatcher, and Red Tree Vole, but potentially is competitive with timber production and habitat for Pacific Marten, Pileated Woodpecker, and Western Bluebird. That’s because species like the Northern Spotted Owls prefer multistoried mature forests, which also tend to store more carbon. Western Bluebirds, on the other hand, prefer vegetation conditions typical in young forests. Because of these differences in habitat preferences, managing for carbon storage, timber harvest and wildlife habitat will take a landscape approach that identifies niche areas that can increase the area of complementary management practices across the whole landscape.

Key Findings

  • Managing western Cascades forests to store carbon can be roughly complementary with habitat for Northern Spotted Owl, Olive-sided Flycatcher, and Red Tree Vole, but potentially is competitive with timber production and habitat for Pacific Marten, Pileated Woodpecker, and Western Bluebird.
  • Northern spotted owls prefer multistoried mature forests, which also tend to store more carbon, making management to store carbon complimentary with management to favor owls.
  • Western Bluebirds prefer vegetation conditions typical in young forests, whereas Northern Spotted Owls prefer multistoried mature forests. Because of these differences in habitat preferences, the two species are considered “competitive” in production. Forest managers generally cannot produce more habitat for one species without reducing habitat for the other species.

Further Reading:

Kline, J.D.; Harmon, M.E.; Spies, T.A., et al. 2016. Evaluating carbon storage, timber harvest, and habitat possibilities for a western Cascades (USA) forest landscape. Ecological Applications 26(7):2044–2059.

Watts, A. 2017. Can We Store Carbon and Have Our Timber and Habitat Too? Science Findings Issue 202. USDA Forest Service, Pacific Northwest Research Station. 6 p.

See also this article by the author: Complex old-growth forests may protect some bird species in a warming climate (Phys Org)
In a paper published today in Diversity and Distributions, a professional journal, researchers in the College of Forestry at Oregon State University reported that the more sensitive a bird species is to rising temperatures during the breeding season, the more likely it is to be affected by being near old-growth forest.