Thursday, January 24, 2013

The “Pristine” Tallgrass Prairie

When I first visited Konza Prairie Biological Station (KNZ) I imagined that I was looking out over the same tallgrass prairie that early pioneers traversed in their Conestoga wagons. Day after day, they travelled through waves of grass stretching to the horizons, with few trees and wide, open sky (Figure 1).

Figure 1: Waves of grass stretching to the horizons at Konza Prairie.
Of course, I knew that some parts of Konza were not pristine. The nature trails that I frequently hiked on Konza passed the Hokanson Homestead and provided excellent views of the limestone barn and house of the Dewey Ranch. Immigrants and wealthy land prospectors established and actively farmed or ranched the area since the 1870s. But the waving grass still convinced me that my site had been little altered by humans.

After some time working at Konza, I noticed that I could easily identify the experimental watersheds of the research site on an aerial photograph, even without extra lines (Figure 2). Fire and grazing treatments imposed as part of the experimental design at Konza altered vegetative structure and composition, not to mention my perception of the “pristine” nature of my research site.

Figure 2: An aerial photo showing the current watersheds and experimental fire and grazing treatments at Konza Prairie. The most noticeable watersheds without the lines on the map are the long-term unburned watersheds, which appear darker because woody species have invaded the grassland.
Soon after, while volunteering on a prescribed spring burn, a seasoned member of the fire crew noticed my inspection of a long scar in the earth on a nearby hillside. “That is the roadbed for the old highway,” he said. One of the main roads into nearby Manhattan, Kansas, used to run right through Konza Prairie. I began to wonder how pristine Konza actually was.

My own studies track the legacy of grazing in tallgrass prairie. Unlike the easy dichotomous distinction between grazed and ungrazed prairie, I have found persistent legacies of grazing five years after cattle last nibbled a blade of grass. Both above- and belowground, these recovering pastures continue to reflect the disturbances that shaped them. When we look at our landscapes, what legacies, from both human and natural processes, do we miss?

I was reminded of the legacies that so often pass me unnoticed while collecting soil cores from my experimental plots on Konza this past fall. Waiting in one core I found an arrowhead from the Native Americans that once hunted on this land (Figure 3). The archeologist that archived the arrowhead guessed that it was about 500 years old, dating from the time when the native people were switching from using spears to more use of bow and arrow. These humans depended on bison for their everyday well-being  and often intentionally burned sections of prairie to attract wildlife to the new growth (Kimmerer and Lake 2001). Humans changed this piece of land long before ranchers replaced bison with cattle or scientists decided that it should be a research site.

Figure 3: An arrowhead found in a soil core at Konza Prairie, reminding us that many human-induced changes are invisible without our research. Our work informs the decisions of land managers, governments, and everyday citizens. Wow!
Some LTER sites explicitly deal with the interaction between human and natural systems, but at Konza, and other remote sites, it can be easy to think that our system is “pristine.” Aside from the arrowheads, old homesteads, scars on the hillsides, and research, our activities as humans have dramatically changed how our world appears and functions.  Nutrient loading, climate change, and altered disturbance regimes are only a few of the ways that our “pristine” sites are touched by human activities. As LTER graduate students, we are challenged to poke and prod our systems to figure out what makes them tick, and what our legacy will be far into the future. Without our research, these human induced changes, like the arrowhead in my soil core, will remain invisible.

Benjamin L. VanderWeide
Konza Prairie Biological Station (KNZ)
Division of Biology, Kansas State University

Kimmerer, R.W. & F.K. Lake. 2001. The role of indigenous burning in land management. Journal of Forestry, 99(11): 36-41. 

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