What’s a forest worth?

mountain biker © Andreea Dobrescu Dreamstime.comWhen I think of an alpine forest, I think of the towering cedar trees that blanket the Cascade mountains near my native Seattle, with trunks so broad you can’t reach your arms around them. I think of the shadowy quiet that envelops me as I wander through a mountain forest in my new home in Austria. I think of the scent of pine needles and the bounce of my feet on a trail softened by forest litter. The value of a mature forest to people like me who love the outdoors—its recreational value—is impossible to put into numbers.

We can, however, calculate the effects of different styles of forest management on more quantifiable criteria. We can determine how much carbon dioxide is taken up from the atmosphere and stored by long-growing forests. And we can estimate how much bioenergy we can sustainably produce by managing forests for biomass harvesting.

This is exactly what IIASA scientists have done for their first efforts in the recharge.green project. IIASA’s role in the project is to use our modeling expertise to explore the various possibilities for renewable energy expansion in the Alps. We are also looking at the tradeoffs and benefits of the different possible scenarios and ecosystem services (ESS). As a first step, researchers Florian Kraxner, Sylvain Leduc , Sabine Fuss (now with MCC Berlin), Nicklas Forsell, and Georg Kindermann used the IIASA BeWhere and Global Forest (G4M) models look at the tradeoffs between bioenergy production or carbon storage in alpine forests.

These graphs show the first results for recharge.green from IIASA’s BeWhere and G4M models, optimizing the location of bioenergy plants to maximize either carbon sequestration (top) or bioenergy production (bottom). The gradiant of green colors shows the amount of carbon storage over the landscape, while the red boxes (and according gradient in red) show the harvesting intensity in different harvesting areas.

These graphs show the first results for recharge.green from IIASA’s BeWhere and G4M models, optimizing the location of bioenergy plants to maximize either carbon sequestration (top) or bioenergy production (bottom). The gradiant of green colors shows the amount of carbon storage over the landscape, while the red boxes (and according gradient in red) show the harvesting intensity in different harvesting areas.

“Managing forests optimally for bioenergy requires more intensive management,” says Kraxner. That means shorter rotations where trees are cut more often. Such a forest is made up of smaller trees that may look more like “close-to-nature plantations” than an old-growth forest. In contrast, managing forests for carbon storage means letting the trees grow older, also good for biodiversity and environmental preservation.

In their analysis, Kraxner and the team compared two management strategies: restricting bioenergy production to a small land area, and managing it intensively, or spreading bioenergy over a large land area but managing less intensively over the whole area. They found that the same amount of bioenergy could be produced by managing a small amount of land area intensively for bioenergy production. This more intensive management on a small area of land would free up a larger land area for preservation and protection or other special dedication to ecosystem services.

“Both methods are sustainable,” says Kraxner, “but the optics are different. Intensification can be a good solution to provide renewable energy and at the same time preserve biodiversity and the more intangible values of mature forests.”

What do you think? What should our priorities be in managing Alpine forests?

    Katherine Leitzell

    About Katherine Leitzell

    Katherine Leitzell is a science writer at the International Institute for Applied Systems Analysis (IIASA), in Laxenburg Austria. IIASA researchers are working on the economic-ecological modelling for the recharge.green project.

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