Tallgrass Prairie Preserve


Andon Zebal (SCA ’08) recently sent me this blog entry recounting his SCA experience.  Andon grew up in Mexico and hopes to return there to work on sustainable forestry and reforestation. This summer, he will embark on a “Reforestation Backpacking Trip,” attempting to see as many  projects as possible as he travels through Mexico and Central America. You can follow his adventures (including his SCA experience last summer) at his blog, Restoring the Americas.

Justin, John and I visited the Tallgrass Prairie Preserve in northern Oklahoma. The preserve is the largest protected prairie remnant in the world. I assumed it was a national or at least a state park, but it turns out the whole thing is run by the Nature Conservancy! We met with Bob Hamilton (in between Justin and me in the picture below), basically the ecosystem manager of the preserve. He has been working with the preserve since before it started in 1989, so the Prairie is basically his baby.

As soon as we got in, we experienced what happens when two incredibly talkative ecosystem managers (Bob and John) get together… just about 2 hours of introductory conversation! Fortunately it was actually quite interesting, with Bob describing to us the process of setting up and starting up the reserve and managing the huge Bison herd on the site. One of the main things that prairie ecosystems need in order to sustain themselves is disturbance, and Bob explained to us that in this area, disturbance has historically come from a combination of grazing animals like Bison and human induced fires. I was surprised to learn that he doesn’t consider lightning to be a significant source of fire. Bob has surveyed the area after lightning storms, and found that what little fires they do start usually die out after burning a small circle around the strike site. If it wasn’t for humans, Bob claims, the entire prairie would be a part of the eastern deciduous forest! Talk about slamming down the barrier between humans and “nature.”

To replicate this disturbance pattern, Bob uses a combination of Bison and massive prescribed burns. He started with a small Bison herd of ~500 and used the existing fences that were there when the property was bought to slowly give the herd room to grow. Basically, whenever the herd gets too big for the enclosure it’s in, a fence is removed and the herd is allowed to use the next enclosure. The herd now has free roaming rights around most of the preserve and numbers more than 2000 head of Bison. The most amazing part of that number is that every year, most of the herd is rounded up for monitoring, medical attention, and science! I say most of the herd because apparently there are some very stubborn old bulls that refuse to be rounded up. In the beginning, the preserve used four-wheelers and cowboys (real cowboys!) to round the shaggy beasts up, but now they make the bison come to them. They use “Bison Treats” and a siren to attract the native cattle to the trucks, and round them up from there.

The other disturbance method is prescribed burns, and the Tallgrass Prairie takes these to a new level. We heard Bob describe a 400 acre burn as “pretty small.” With just a couple of water trucks and some torches, these guys burn about a third of the 39,000 acre preserve each year! What I found really interesting was the interaction between the fire and the Bison. Each year, the bison find the recently burned areas and prefer them as feeding areas. After an area hasn’t been burned for about three years, the bison lose interest in it entirely. The burn patches are chosen with a random center, and then a reasonable seeming polygon is drawn around it. I didn’t see a single square on the burn map!

The preserve places a high value on creating habitat diversity by varying the timing and size of burns, and it seems to be working. By not doing any one uniform thing to the landscape, they prevent the boring, agricultural look of other rangelands, which are usually burned all at once or even worse, herbicided all at once. In the surrounding cattle ranches, the management style is to knock out anything that isn’t a grass, because “If it ain’t a grass, it’s a weed.” On the way in, we saw crop dusting planes doing just that, spraying a broadleaf herbicide from the air. It reminded me of agent orange and the damage it has done to Vietnam and Colombia’s forests.

The Nature Conservancy has been trying to change all this, and is doing some experiments on alternative methods such as patch burning rather than full burns and spot spraying rather than aerial spraying. Both of these have been found to greatly increase biodiversity while providing the same amount of weight gain for the cattle. The Nature Conservancy, long criticized for their sole use of parks as a conservation method, seem to have finally gotten past their “park” mentality and are now thinking about the entire landscape as a unit of conservation. In Osage county, where the preserve is located, most of the land is held by a few large landowners, including the Nature Conservancy, the Mormon Church, and Ted Turner. As Bob said it, “You have to own at least 20,000 acres or more to wear the big hat around here.” This means the preserve only has to talk a few people into changing their land use practices, but it also means that if they can’t talk one person into it, they lose a significant portion of the landscape. So far, though, it seems that they are making quite a bit of headway, getting their neighbors engaged in conservation.

Anyway, enough science, it’s time for pictures!

Justin overlooks the herd. From this point, the prairie stretched uninterrupted to all horizons.

A Bison cow and her calf nursing. Nature is so beautiful.

Well, most of the time.