Tropical forests provide countless goods and services that help sustain human life. Given the rapid conversion of forests to agricultural lands, scientists say it is critical that we prioritize conservation of forest ecosystems. While economists have attempted to quantify the economic value of tropical forests, these estimates may overlook the intricacies of the landscape. According to a recent study in Biological Conservation, economic analyses of forests tend to neglect areas containing high biodiversity.
To better understand why this is, researchers applied a meta-analysis—an analysis of an analysis—to forest evaluations throughout the tropics of Latin America, Asia, Oceania, and Africa. They looked at 30 previously published articles from The Economics of Biodiversity and Ecosystems (TEEB) dataset to determine if regions with high economic values for ecosystem services overlapped with areas of high biodiversity.
The team isolated variables that potentially influenced economic value in each case, such as climate, population density, and proximity to cities. They then created a model to predict total ecosystem services value using three categories of services—provisioning, regulating, and cultural. The model also generated a global map of economic values of tropical forests, with a mean of 1,312 international dollars per hectare of the given year.
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The meta-analytic model predicted total ecosystem service values by tropical forests throughout America (A), Africa (B), and Asia and Oceania (C). Red areas indicate higher value in international dollars per hectare year. Credit: Carrasco et al. Click image to enlarge. |
The maps created by lead author Dr. Roman Carrasco, an assistant professor at the National University of Singapore, and his colleagues display dissimilar biodiversity and economic values of ecosystem services, suggesting that policies developed exclusively from an economic perspective might fail to substantially conserve high biodiversity areas in tropical forests.
Not always paired: ecosystem services and biodiversity
Ecosystem services represent any of the goods and services that humans derive from nature, whether directly or indirectly. Carrasco, cited “climate regulation, flood protection, water filtration, carbon sequestration, provision of non-timber forest products (e.g. wild mangoes)” as common examples of these benefits.
While policymakers have presumed that ecosystem services will increase with higher biodiversity, or species richness within an ecosystem, scientists are finding that this could be an oversimplification.
“It would be…ideal for land-use planning [if] the places that are highly biodiverse also presented the highest economic value of ecosystem services,” Carrasco told mongabay.com. “We show, however, that this is not the case for ecosystem services in general and warn that we should not conflate biodiversity with ecosystem services values. We need to cater [to] each of them separately in our policies.”
How, then, can economic and other analyses better incorporate biodiversity’s value? Carrasco provided the example of bioprospecting to illustrate the potential economic valuation of biodiversity. Bioprospecting operates under the assumption that there is a likelihood that undiscovered cures for diseases—e.g. cancer and HIV—or other valuable resources, could exist within the same tropical forests threatened by deforestation. Therefore, the uncertain potential for future high value discoveries must be factored into any economic analysis.
A tree fern in the Kosnipata Valley of Peru. Photo by Rhett A. Butler / mongabay.com
Still, this method is not without its limitations.
“[T]his value only scratches the surface of the value of biodiversity, which I think goes beyond economic terms. It has an intrinsic value that I don’t think, at least with the current tools, we are in [the] condition to quantify,” said Carrasco.
It matters where the people are
An oft-overlooked dynamic in assessing economic value is the role played by human population density and its distribution across the landscape.
“[Population density] is the key [as to] why biodiversity and economic value of ecosystem services don’t go hand in hand,” explained Carrasco. “For most services except carbon sequestration or containment, the presence of people to benefit from the services is essential for their economic value to be realized.”
Supply and demand regulate the realized value of any ecosystem benefit, and this, in turn, is dependent on the ease of access to that resource or service. In this case, the authors measured accessibility as the time required to travel to a city.
Carrasco further clarified the set of interactions at play, stating, “…if a forest offers flood protection but nobody is living downstream to benefit from that service, the economic value is zero. If, on the other hand, a large city benefits from that service, then the value is very large.”
Within more remote forests, additional dynamics occur.
“The farther we go from large human settlements, the more pristine primary tropical forests we find; these forests are less disturbed and contain, thus, more biodiversity. This makes economic value and biodiversity…spatially incongruent, that is, they occur in different places,” Carrasco described.
In addition to leaving behind biodiversity, economic surveys of these areas often ignore the vast cultural applications of forests, even when only utilized by a comparatively small community of people. In fact, in these cases, forest goods and services might actually be more valuable to local recipients than their urban counterparts. The Poverty and Environment Network of the Centre for International Forestry Research indicates that up to one-fifth of household income comes from forests in tropical developing countries.
Tropical forests can offer greater economic and food security during periods of reduced agricultural productivity, for instance. Additionally, forest products supplement local diets, improving nutrition and community health.
Red bromeliads (Racinaea) in Manu, Peru. Photo by Rhett A. Butler / mongabay.com
Better applications for land management
As the first comprehensive meta-analysis of ecosystem services and biodiversity in tropical forests, the study provides valuable insight for future land management initiatives in the tropics.
Carrasco told mongabay.com that the findings “can support land-use planning for conservation and identify areas where the strongest trade-offs with deforestation occur. Without this information, forest conversion occurs uninformed, taking the value of forests for granted.”
By capturing more variability across the tropics, the study also offers crucial “spatially explicit information of the economic value of services by tropical forests” that was previously limited in both the scope and diversity of ecosystem services, Carrasco said. He hopes that in the future, others will produce more localized maps to account for cultural and environmental nuances within tropical forests.
Carrasco believes there is much room for improvement, especially in dissolving the divide between the fields of ecology and economics.
“Ecologists and economists use different technical terms, which may make communication difficult. They also study in principle different systems and with different tools,” he said. “I believe the understanding between the disciplines will grow in the future as a result of the strong pressure we are posing on the environment.”
Above all, Carrasco recommends a cautious and multi-criteria approach to land policy. He calls on policymakers to “…protect ecosystems for the intrinsic value of biodiversity, [as] the economic argument of the value of ecosystem services will probably not be sufficient.”
Citations:
- Carrasco, L. R., T. P. L., Nghiem, T. Sunderland, and L. P. Koh. 2014. Economic valuation of ecosystem services fails to capture biodiversity value of tropical forests. Biological Conservation 178, 163-170.
