Carbon markets and related international schemes that allow payments to landholders for planting trees, sometimes called carbon farming, are intended to support sequestration of carbon from the atmosphere. But they will have harmful effects, such as degrading ecosystems and causing food supply problems, if other benefits and disbenefits from revegetating agricultural landscapes are not also taken into account in land-use decisions, according to an article published in the October issue of the journal BioScience.

Brenda B. Lin of the Australian Commonwealth Scientific and Industrial Research Organization and her colleagues assessed a variety of ways that people have attempted carbon farming. Simple maximization of profit can lead landholders accessing carbon markets to create monoculture plantations, which do not support biodiversity and provide few environmental benefits to local inhabitants. But alternatives such as planting strips of trees on farms, agroforestry—integrating trees into cropping systems—and revegetation of marginal or crop land can sequester carbon while also yielding a broad spectrum of environmental benefits.

These benefits may include, for example, reduced pollution outflow and erosion, and better wind protection, pest control, and pollination. What is more, schemes that have local participation and buy-in are more likely to be successful over the long term, because they can draw on local knowledge about trees likely to thrive and will remain popular. Lin and her colleagues urge organizers of carbon farming schemes to move beyond a carbon-only focus and consider cobenefits of revegetation, while involving local inhabitants, not just private landowners, in policy decisions.