ECO-HISTORY OF ATLANTA’S URBAN FOREST WITH KATHRYN KOLB

interviewed

by Aaron Searcy

Aaron Searcy Could you tell us a little bit about EcoAddendum and your role there?

Kathryn Kolb I’m the executive director of EcoAddendum, and I’ve been designing and running our current program since 2013. It’s a small organization, and basically what we do is lead educational walks and outings in natural areas, both local and regional. We look at tree species and native plants and show how to read a forest’s history and ecology, just by looking at its species and growth forms. Our purpose is to show people the high value urban forest here, which makes Atlanta very unusual and perhaps unique among major cities in this country.

I’m also leading stewardship programs, which is working with a community or a municipality around a particular park or green space. It’s a year-long class, and what I do is essentially train an inner circle of community green-space leaders so they become experts in restoring that particular green space.

And then the other thing that I’ve started to do in the last few years is GIS mapping of parks and green spaces—doing inventories and writing management plans so greenspace managers and volunteers have a good blueprint of what is in a particular park or green space, including species inventories, and a management plan of how to restore it.

A: You mentioned that Atlanta is relatively unique when it comes to its urban forests. How did Atlanta come to be called the city in a forest?

Kolb The story of Atlanta’s forest is rather interesting. This country was settled by Europeans coming from the eastern seaboard and moving west. A lot of our major cities in the eastern United States date back to the early 1600s, but the area that is now metro Atlanta was part of lands transferred at the Treaty of Indian Springs from the Muscogee Creek Nation in 1821. Metro Atlanta was mainly the territory of the Muscogee Creek, but the border was the Chattahoochee River, which runs as a diagonal across the top of Atlanta. Northern suburbs and exurbs would have been in Cherokee territory, but the main part of metro Atlanta would have been Muscogee.

Our area, our landscape, was mostly old-growth forest in 1821. There were some settlements, but these were not widespread before the treaty. And the land lotteries took some time, so people didn’t really start cutting the trees and settle en masse so to speak until the 1830s or even the 1840s. That is really late in the game—nearly two hundred years after Harvard University was founded. At that point, it’s only a couple of decades until the Civil War. And of course, this area and the rest of the South was economically depressed after the war, so Atlanta was not really a destination until later in the twentieth century, after air conditioning came online in the 1960s. And at that point, people were no longer traveling by horse and cart—but by cars and highways. So when Atlanta does experience its first major building boom, it’s in a sprawl growth pattern.

The silver lining of that sprawl pattern for our forests is those steep slopes, narrow stream corridors and rocky outcrops were not desired for farming, and they weren’t desired for building. So as Atlanta experienced this big building boom, these little pockets of really high-value forest that go right back to Muscogee Creek days remained in many residential neighborhoods. People have oldgrowth forest remnants in their backyards all over metro Atlanta.

Underpinning all this, we have an amazing network of watersheds here.

I mean every neighborhood has a series of creeks. We have three major watersheds in metro Atlanta, which is located on the Eastern Subcontinental Divide. Two of them go to the Gulf of Mexico, and one goes to the Atlantic Ocean. So we have tons of creeks and streams, and those narrow stream corridors were not desired for building or farming either.

The other thing that’s interesting about metro Atlanta is it’s a city of hills. So Atlanta didn’t really have that same kind of big farm, plantation agricultural base that other parts of Georgia and the South had. A lot of the farms were smaller holdings, with lots of dairy farms. So our landscape wasn’t as impacted. With less row-crop farming, soils were less disturbed.

A: It really was a confluence of history and topography that made Atlanta the city in a forest. Can you describe what these ancient forest ecologies look like in Atlanta today and how you identify them?

Kolb One of the ways you can tell all those older forests is by tree diversity, which depends on the ecological niche.

Our mature forest is a hardwood forest often dominated by a variety of species of oaks. You’ll also have a lot of tulip popular, and hickories are also a big part of the older forest ecosystem here. Hickories grow very, very slowly. Oaks and hickories are most often on the dryer ridgetop sites.

In the flood plains, you’ll have more sweetgums, box elders, sycamores, and river birch. On moist slopes, you’ll start to find slow-growing black gum. You will also find some midstory trees such as sourwood, the native deciduous magnolias, and large beeches. Beeches also grow very slowly. You typically see them more in moist environments along creeks, but when you see big beech trees in a landscape, you know that you’re looking at old growth.

Everyone talks about how Atlanta has so many pines, but in our ecosystem, these are not the apex species. Pines come in after there’s a disturbance. So if you walk in a forested area and you see a whole lot of pine, what that tells you is that would probably have been a pasture or field in the 1930s. In any case, the landscape today is a patchwork quilt of more and less disturbed native forest.

The smoking gun of how we identify old-growth remnants is the plant communities under the trees. Certain kinds of plants—typically those high-value spring ephemerals that everybody loves, trillium and bloodroot and things like that—whose seeds don’t travel. So if you’re looking at plants with seeds that don’t travel far from the mother plant, you know that those plants have been in those same soils for hundreds or maybe thousands of years.

I know it sounds kind of common to say it now, but all these things are interconnected in many ways that we don’t yet understand. There are relationships between certain types of plants, which have relationships with certain types of fungus that are having relationships with certain types of trees. And then of course myriads of other microorganisms are involved. So the forest itself—that rich, high-value, old-growth forest—is a community which depends on soils that are largely intact.

A: These remnants of old-growth forest may seem like something of a novelty, but could you describe some of the ecological services the forest is actually providing for the people of Atlanta?

Kolb Truly the forest is doing everything. Trees reduce stormwater runoff in about six different ways. A mature forest loses only about 2 percent of stormwater runoff in a storm event. If you have a park that a few trees widely spaced apart, and the grass is not a meadow but cut short, the way they often are, that’s actually losing 70 percent of stormwater to runoff—70 percent is closer to cement than forest. What’s happening in metro Atlanta, and the reason we’re getting so much more flooding, is that Atlanta is converting forests and pervious areas to impervious areas at a very, very rapid rate. When you tear down that smaller house and build that bigger house, you’re grading the landscape, you’re turning what was wooded area into lawn, and you’re also just adding a lot of impervious material, whether it’s in the driveway or the rooftop. It’s unsustainable in terms of the environment. flood vulnerability in atlanta The Centers for Disease Control and Prevention (CDC) has developed a Social Vulnerability Index using demographic factors such as socioeconomic status, household composition and disability, minority status, and others. Higher vulnerability refers to conditions of exacerbated environmental stresses on human health and wellbeing.

The forests are also very important to human health. Even if you never set foot in the forest but live within a half mile of a forest or green space, trees are producing chemicals that are called phytoncides, and some of those actually boost the immune system. If you live near a forest or green space, the health benefits can be the equivalent of $20,000 a year in income.

So when we talk about community, the other thing about metro Atlanta is that some of the best forested areas are in communities that are primarily communities of color. When we talk about environmental justice in other cities and Atlanta, there are many areas where people of color are often living in areas such as near railroad tracks and landfills where environmental conditions are poor— but interestingly there are many communities primarily of African American folks that have very highvalue forest in metro Atlanta.

If you talk about taking those forests away as development increases, you’re actually taking away a health benefit that is already being provided right now. Some of these communities do have people that are of modest means, so if you take the urban forest away, then you’re burdening people with extra healthcare costs, including increasing costs for public safety. When it’s hot in the summer, people are angry, so you may get extra encounters with the police. There are many, many ways in which being around healthy, natural spaces improves quality of life and human health.

The forest that has the highest ecological value—that has the oldest trees, best soil, the most plants, the best ecology—is also the one that’s serving the best benefits for green infrastructure and human health.

A: That runs a little bit counter to what I've heard some folks argue that old growth forests aren't quite as productive or valuable as younger forests. But it sounds like you're talking about productivity in a different sense. You're thinking about value and services that aren't being factored into the equation.

Kolb Actually, if you talk about ecology, the science is there. Older forests sequester more carbon. That idea that the older forests are kind of tired and aren’t doing as much is an absolute myth. That is a weird, human-centered thing going on.

Every time I’m at a meeting and we have development community representatives, I can’t tell you how many times I hear ‘That tree’s old. It’s about dead. It’s eighty years old.’ If it’s as old as an old person, we need to do away with it. But trees don’t grow on that scale. There are water oaks, which are common in metro Atlanta, that are starting to have health problems at about 120, maybe 150, and they’re maxing out at about 200. But black gums are living 700 years or more. White oaks, five hundred years or more. Post oaks, five hundred years or more. Most of the overstory trees in our ecosystem, their natural lifespan is three hundred to six or seven hundred years. And no one is allowing them to live that long.

The whole forestry education system has been really geared towards the timber industry. People go to forestry school and learn how to estimate board feet. The reason that people are saying that a forest is maxing out at a certain age is because it’s not putting on more board feet fast enough. But that is actually not true. The fathers of modern forestry and the US Forest Service in North Carolina took meticulous records in the late nineteenth and early twentieth centuries, and they were measuring giant amounts of board feet that we don’t have today because the trees haven’t had time to grow that long. We’ll need to wait for five hundred, six hundred, or a thousand years before we’ll see trees that look like the old-growth trees we cut. And we cut almost everything. The entire Southeast was pretty much cut between 1870 and 1920. ecological corridors in and around the south river watershed Ecological value in this case is based on occurence of interior forest cores, floodplain forest, wetlands, and mature soil composition.

A: It's a similar story here in the Smokies. There's a lot of wonderful forest here, but in a sense, it's also a postapocalyptic landscape. Almost all of the Smokies have been logged, but it makes me wonder. Atlanta is pretty far south, but do you consider Atlanta part of the greater Appalachian system?

Kolb That’s a fascinating question. What I have found is that Atlanta seems to be a break point. In north Atlanta neighborhoods, on steep rocky slopes, you will find a lot of species that are common in north Georgia and up in Sandy Springs along the Chattahoochee corridor, but by the time you get down to the southern end of the city, where it drops down into the flatter, lower Piedmont, those species aren’t found. Atlanta is arguably at the end of the Appalachian system as you’re heading down into the Piedmont in Georgia.