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Ecosystem Goods and Services Series: The Biophysical Basis
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(A collaborative series by David Zaks, Chad Monfreda, and Hassan Masum.)

You don't miss it 'till it's gone. That sums up the thinking behind ecosystem good and services, which is all about reconnecting an economic system that has forgotten its ecological roots.

That may mean putting a monetary value on ecosystem services. Indeed, a lot of people are trying to put a dollar figure on nature by asking questions like, "How much is a forest's carbon sequestration worth?". But even before broaching monetary valuation, we need to ask which services we care about, and how we should go about measuring them. In other words, the first thing we need to ask about is the biophysical basis of ecosystem services.

Fortunately, ecology is ready to help. Ecologists are still doing the esoteric studies they're good at, but they're increasingly using ecosystem services to frame and even direct their research. Ecosystem services as a legitimate research topic came of age in the 1990s with the kinds of pioneering research collected in places like Gretchen Daily's seminal book, Nature's Services.

More recently, the idea that we need to take better stock of the link between ecosystems and human well-being was the rationale for the biggest international ecological assessment ever. The Millennium Ecosystem Assessment (which is summarized nicely by GreenFacts) made a massive contribution to decision-makers, but, perhaps more importantly, created a common language to cut through complex problems. The MA divides ecosystem services into four types:

ma_egs.jpgProvisioning services are the products people obtain from ecosystems, such as food, fuel, fiber, fresh water, and genetic resources.

Regulating services are the benefits people obtain from the regulation of ecosystem processes, including air quality maintenance, climate regulation, erosion control, regulation of human diseases, and water purification.

Cultural services are the non-material benefits people obtain from ecosystems through spiritual enrichment, cognitive development, reflection, recreation, and aesthetic experiences.

Supporting services are those that are necessary for the production of all other ecosystem services, such as primary production, production of oxygen, and soil formation.

So what do these services mean on the ground? A good example comes from Australia, where salty soils are putting agriculture in jeopardy. The process is called salinization and happens when rising groundwater deposits salt in the soil. Left unchecked, salinization makes it impossible for plants to grow. Normally, trees stop this from happening by keeping the water table low--that is, they provide a supporting ecosystem service by maintaining the conditions that let plants grow. But when farmers began to clear trees for crops and pastures on a big scale in the 1980s (i.e. tried to maximize provisioning services), they inadvertently removed the supporting service that makes crops and pastures possible in the first place.

Bees and other pollinators provide another crucial, yet under-appreciated supporting service. It has been shown that decreases in natural habitat near agricultural fields lead to declines in local bee populations, and require that bees be brought in to do the once free service of pollination.

Of course, the MA's typology of provisioning, regulating, cultural, and supporting services isn't the only conceivable framework, but it is a useful one for an inherently multivalenced topic that pulls together science, policy, business, and the public. Whether it's tsunami-buffering mangroves, crop-pollinating insects, or the ecology of disease, ecosystems have a real impact on people's lives. But the story doesn't stop there. Human well-being feeds back into ecosystem services in the decisions people make about the places they live, the things they buy, and the species they protect.

In other words, it all becomes very complicated, very quickly.

We didn't need an international scientific assessment to tell us that, but in the very act of pooling knowledge on what we do know, the MA highlighted what we don't. The architects behind the MA recently spelled out its biggest gaps in the journal Science. They point out a host of challenges, some direct to ecology, others to the interface between ecology, economics, and policy. A common thread, however, is the need to get a better handle on the biophysical basis of ecosystem services. Major gaps, for example, exist in the theories that link biodiversity to ecosystem function, and local ecosystems and global environmental change. But the most basic gap is in the data to support such studies:

Despite advances in monitoring technology, the lack of uninterrupted time series of sufficient length to reflect social-ecological dynamics is a major problem. More disturbingly, the information available today is sometimes of poorer quality than historical information. For example, hydrological monitoring networks in many countries are deteriorating, and institutions to maintain long-term records of Earth observations from satellites are not in place.

Recent work, however, is delivering the basic, biophysical information we need to move forward.

Case studies are extremely useful in defining and monitoring services on a local scale, but in today's global village we also need the big-picture perspective of how our ecological landscape is changing. There have been several projects that have done so on a regional - continental scale. The Advanced Terrestrial Ecosystem Analysis and Modeling project (ATEAM), which we talked about here, assessed current and potential future services for Europe, while the State of the Nation's Ecosystems report authored by the Heinz Center has a U.S. focus. The Heinz report was first published in 2002, and will be updated in 2007 with new data and updated indicators, which they hope will more easily integrate into the policy process.

The lack of availability of data on the stocks and flows of ecosystem goods and services is hampering the growth of this nascent field. The Millennium Ecosystem Assessment pooled data from previous studies to get a baseline of ecosystem goods and services around the world, but a key ingredient for sustainable ecosystem management is dynamic data on the state of the system. One way to get a grasp on our planetary goods and services is by leveraging the constellation of satellites orbiting Earth. MODIS satellite imagery gives us a snapshot of the Earth every 2-3 days that shows the supporting service of primary production, a proxy for carbon sequestration.  Future satellites, like Carbon-3D, are being designed to mesh directly into the ecosystem goods and services framework.

While satellites are very good at detecting large scale changes, on-the-ground sensors can easily monitor ecosystem goods and services on a smaller scale. A global real-time distributed wireless network of sensors that monitors everything from water and air quality to agriculture and carbon stocks is the trajectory that monitoring activities are taking. Examples of this type of wireless sensor network have been used in a few ecological studies, but if rolled out on a larger basis could give us a glimpse of the ebbs and flows of our global ecosystem. The emerging ecological panopticon will give us yet another means of understanding our home planet.

Now that we have (or will have) the information necessary to manage and value ecosystem goods and services, what is the best approach to take? How should the benefits of ecosystems be distributed?  Stay tuned for future posts as we delve into these issues...

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What an excellent article! This really is a going to be a great series, I think.

Keep 'em coming!


Posted by: Andrew Yellof on 9 Dec 06



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