Seven Thousand Miles of Science
When you do fieldwork far from where you are based during the year, particularly experimental field work, you find out just how much stuff can fit in a mini van. I go to school at the University of Wisconsin Madison but I do my research in Yellowstone National Park, Wyoming. This summer I jammed as much equipment as possible, two field techs, and my cat into a car and rolled out across Dakota prairies toward an adventure of bears, mountains, thunderstorms, and Big Skies of Yellowstone. Neither of my two field techs, both of whom are undergrads at UW, had been to Yellowstone and their level of excitement was palpable. Matt passed the 1500 miles of driving time from WI to WY by blasting us with loud, rambunctious indy rock music and asking a series of random but incisive questions, “If you were to have any super power what would it be?” he’d ask. “If you had to choose only French fries or onion rings to eat for the rest of your life, what would you pick?” Aisha, my other tech was quieter. She preferred to listen more than speak. Often you could see the wheels cranking behind those eyes processing inputs at frightening rates. Then the questions would spill out in a river more focused on trying to understand how you live your life, what motivates you, why you are who you are. Then there was my cat. After two days, she had enough of being jammed into a mini-van with three humans. Just as she started a cacophony of meows, the mountains exploded into view. Hello Rocky Mountains. Hello Yellowstone.
Yellowstone National Park is a phenomenal landscape of mountains, clear blue water, long miles of dense conifer forest, and of course the iconic wildlife and thermal features. Yellowstone is also a shining gem of the western United States, one of the few natural tracts of wilderness left in a sea of anthropogenic development, land use, and recreation. It largely escaped human impact because it is incredibly rugged and historically isolated. In fact, one place in Yellowstone is the farthest point from any road in the continental United States. However, profound beauty and isolation may not protect Yellowstone from consequences of climate change. Infrequent severe wildfires are natural and integral to much of Yellowstone’s forests, and have been for millennia, though projections suggest that warming and drying conditions may cause large increases in fire activity that could exceed the historical and even paleo-ecological range of variability. While forests of Yellowstone are well adapted to the historical natural disturbance regime, it is likely that expected changes in climate and fire could initiate radical changes in the forests. However, what those changes may look like and what specific mechanisms might drive those changes remain poorly understood.
My research focuses on understanding how changing climate and fire regimes are likely to alter forest structure, tree species assemblages and important ecosystem functions, like nitrogen cycling. Clearly we had a whole lot of work to do this summer. First on the agenda was a project led by Aisha to understand how microbial community composition (a key variable in soil nitrogen cycling) varies across stands of different densities and across gradients of climate. Microbes are the underappreciated foundation of many ecosystem functions. They are the ones in soils that decompose organic material and convert it into plant available nitrogen forms. They also respire carbon back to the atmosphere as CO2. So microbes rule the day and the types of microbes that are in a forest is important. Climate can really influence both what type of microbes are in forest soils and how active microbes are when they are present. But trees strongly compete with microbes for nitrogen and thus can also alter the soil microbial community. From a mechanistic perspective, we really don’t understand how important climate versus tree density is in shaping microbial community composition in young postfire forests. But we will when Aisha completes her research. So for two weeks we collected hundreds of soil samples across gradients of climate and tree density in Yellowstone. Needless to say, soil collection is dirty, hard work and the lab work for such studies can be even more challenging. But we did much to keep spirits high.
Microbes aren’t the whole story, though, so for the next several days we collected soil cores that I had transplanted last summer and left to incubate for the year. This was a pilot project testing the concept for a complex in situ transplant experiment to see how the mineralization of nitrogen might be influenced by future climate and stand density. Both of these projects will help to improve our understanding of young 21st century forests in the northern Rocky Mountains.
Yet, as climate dries and droughts occur more often, there is the possibility that forests may not regenerate after fire at all (or at least at the same densities as before they burned). The final project we worked on is a field experiment and significant chunk of my dissertation exploring the climate mechanisms that might constrain postfire germination and establishment of important conifers in Yellowstone. This entails harvesting huge quantities of soil and transporting it in very heavy packs to our experimental sites. The field techs’ eyes always get a little large when we load up our first packs. But by the second day they are leaving the old timer (me) in the dust.
It’s funny. We think of science as so heady, deep, and it is. But as a field ecologist there is what we do at our desks and then there is what we actually do in the field. I study complex forest responses to climate-disturbance drivers during profound times of change. In the field, I move lots and lots of soils around. The point is that being a good scientist requires a range of skills from being strikingly creative to deeply practical.
I guess the point I’ve learned over the last few years is that good field ecology requires a hell of a lot of hard work, 7000 miles worth. But if done correctly and rigorously, we can answer pressing and important questions about the natural world that we live in and depend on.
Photos: W.D. Hansen & M. Norman
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