“What’s that good for?” my dad asked, pointing to a tree as we walked a Hawaiian trail in the mid-1980s, when and where I was in graduate school.
I had no idea what it was “good” for, but I was also puzzled by the question. Why does any living thing need a practical use by humans to justify its existence? If there is none, is it worthless?
Twenty-plus years later, “ecosystem services” is the core of a course I teach.
I certainly wasn’t exposed to a hotbed of pro-environmental thought growing up on a farm in central Minnesota. The area was recently represented by conservative congresswoman Michelle Bachmann. In the 1960s the federal government condemned much of our farmland, along with that of many neighbors, to create the Sherburne National Wildlife Refuge. There’s still resentment towards heavy-handed conservation in the area, in part because the land was taken by suit-wearing folks living in the very heart of cities – the exact opposite of a natural environment. Their own backyards were nothing more than manicured lawns.
Most rural folks care deeply about natural resources for fishing, hunting, and farming. That’s what rural land is “good” for. But what we get from the natural world goes way beyond food, and it was my participation on Durham’s Open Space and Trails Commission that began my thinking about “open space.”
Forests, pastures, and fields in rural areas, and anything ranging from small gardens to large parks in urban environments counts toward urban open space. Some developers push to label large concrete plazas as “open space,” but that’s like calling Twinkies “food.” But even single trees can make an appreciable dent in the hard urban landscape: think about the ongoing loss of Durham’s grand old oaks, or the huge one that lived and died in front of E.K. Powe Elementary School.
What good is open space, or green infrastructure?
In cities we spend money on stormwater and sewer pipes, electrical lines, roads, sidewalks, schools, and sewage treatment plants because they serve important and clear purposes. Defining “urban ecosystem services” helps value green infrastructure. Say Durham suddenly had a million dollars drop in its budgetary lap, how could proponents of trees argue amongt all of these other important and competing needs for a slice of that windfall?
Ecosystems across the vast expanse of Earth provide a long list of services including food and oxygen, pollination, temperature control, clean air and water, and nutrient removal. In urban environments the list of ecosystem services includes reducing city temperatures, lowering air-conditioning costs and improving air quality by slowing the chemical reactions that produce bad air.
Durham’s poorer urban areas have less green infrastructure, likely partly responsible for worse health outcomes. For example, a recent study from Toronto concludes that adding 10 more trees to a city block, just a four percent increase in street tree density, provided a self-reported health perception benefit that’s equivalent to an income increase of $10,000. Even the provisioning of solitude from urban trees must be considered a service, with studies showing reductions in domestic violence and crime with more open space. Humans do better with trees.
We lose green infrastructure as the city develops. When private property owners redevelop a parcel, every square foot of building space represents profit to be gained, and every square foot left as open space represents unfulfilled profit. One saving grace, though, is that green infrastructure includes artificial ecosystems such as green roofs, constructed wetlands, and even the grass-lined ditches that filter pollution from the stormwater that flows from our roads and roofs. In our area, this stormwater becomes our drinking water.
Incredibly important to preserve are the tree-rich stream buffers that stabilize streams, remove nitrogen, and prevent stream erosion. Very strong science shows these buffers should be no less than 100 feet in width for a variety of reasons, yet our legislature is reducing them to 30 feet to open up yet more land for development. As with most environmental problems, the profit gained from exploitation is a private benefit while the public bears the consequences of the lost ecosystem services.
And that brings back the “what’s that good for” question of valuing nature only through its utility to humans. We know that our urban carbon emissions caused changes that hurt polar bears and mountain-top species, and our urban stormwater affects downstream endangered clams, frogs, and fish. By not addressing environmental problems, haven’t we implicitly valued human desires above the persistence of each and every species on Earth?
Will Wilson teaches ecology at Duke University. You can reach him at firstname.lastname@example.org.