PLANTING TREES
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What do We Know About Tropical Forest Restoration and Where do We Go Next?
Holl, KD. 2017. “Research directions in tropical forest restoration.” Annals of the Missouri Botanical Garden 102:237-250. https://doi.org/10.3417/2016036.
In the past decade, numerous global, national, and regional targets have been set to restore millions of hectares of tropical forest to achieve multiple goals, including carbon sequestration, biodiversity conservation, improvements in the quality and supply of water, and support of human livelihoods. But, the question remains as to how we are going to scale up forest restoration given limited resources and the primarily small scale studies that have been done to date.
In this paper, I summarize what we know about tropical forest restoration and where we need to go next to implement successful large-scale tropical forest restoration projects, drawing on a range of examples, primarily from Latin America. Research over the past two decades has shown that a host of abiotic and biotic factors, such as lack of seed dispersal, high seed predation, and eroded and compacted soils can slow tropical forest recovery. The specific barriers to and rate of restoration, however, vary greatly from site to site. Hence, restoration strategies must be tailored to the natural resilience of the ecosystem and the ecological and socioeconomic goals of the project.
Several steps are critical to meet the ambitious forest landscape restoration plans that are being proposed. First, we need to increase the spatial scale of both restoration projects and studies. This will require developing creative and cost-effective restoration methods that often integrate restoration with ongoing human land uses across the landscape. Second, forest restoration doesn’t happen overnight, so we need to plan and monitor forest restoration over multiple decades rather than for just one or a few years. Third, it is critical to engage a diverse group of stakeholders in all stages of project planning, implementation, and monitoring, as well as associated restoration research. That way, stakeholders are more engaged in the outcome and research projects lead to direct management actions. Finally, it is essential to improve the sharing of information between restoration practitioners and scientists regionally and globally so that restoration efforts are informed by the latest scientific knowledge and the successes and failures of other projects.
A 7-year old 300-ha forest restoration project in the Atlantic forest of Brazil, as an example of the scale we need to be working at to scale up tropical forest restoration efforts. (photo by Karen Holl)
The PARTNERS connection
The topic of this symposium was inspired in part by discussions at the first PARTNERS meeting in Storrs, CT. Many sessions at that meeting focused on the reality of large-scale restoration and the ambiguity about how that restoration would be enacted. It later occurred to us that it was ironic how the moment when restoration ecologists are called upon to scale up ecosystem restoration is also the moment when the central premise of ecological restoration is under intense scrutiny. As we planned for Missouri Botanical Garden’s annual symposium, this paradox stood out as a rich topic for discussion. Six PARTNERS members presented at the symposium. The symposium itself is described in a blog post on Natural History of Ecological Restoration.