A Piece of Home Where the Cows Roam

“Welcome to Boston,” a voice over the airplane intercom announced. Already 7,955 miles away from home, I still had an hour-long car ride ahead of me. I fought through heavy eyes as the city skyscrapers blurred into towering trees. Finally, we turned onto a dirt road, and the 22 hours of travel to Petersham came to an end. Stepping out of the car into the cold night, it was clear I had left the warm summer breeze, sandy beaches, and vibrant blue ocean of Guam behind.

Soon after, we visited where I would be spending most of my working day – the Harvard Farm. As I took in the sea of green dancing in the cool breath of summer, I came to the realization that although the setting was different, one thing remained constant between home and Harvard Forest: the valuable balance of sustainable agriculture and conservation. This idea is the center of my summer project under the mentorship of Martha Hoopes.

The Harvard Farm is a unique place to see this interface of agriculture and conservation. An abandoned golf course, the farm land is slowly reverting to forest. The idea of a growing forest appears as a win for conservation, but reforestation threatens the home of several plants and animals that thrive in the unique habitat only grasslands provide. At the Harvard Farm, cow grazing is being used experimentally to maintain the grassland habitat. Although helpful for maintenance, long term effects on plant communities of constant disturbance from grazing are still not entirely understood. My project is the third year of a long-term study that aims to understand how cow grazing alters the dynamics of plant communities.

At the farm, my research partner, Alina, and I survey plant communities in permanent plots designated in three areas of different grazing intensities: traditional grazing, rotational grazing, and no grazing. We record what plants are present and estimate what percentage of the plot they cover. We are interested in the similarities and differences observed between areas and over time.

These similarities and differences may be a result of not only grazing but also the presence of certain plants in the plot. One interesting example is clover. The presence of clover appears harmless on the surface as it does not seem to directly disturb or compete with neighboring plants, but clover fixes nitrogen, meaning it can take nitrogen from the air and convert it to different nitrogen compounds more useful to plants. The altered soil may provide an ideal habitat for invasive species that compete with and disturb native species. Looking at how clover promotes the spread of invaders is the second component of my project.

To study the effects of clover, we survey plant communities in plots with and without clover in a similar manner as the survey of the permanent plots. In these plots, we are interested in the ratio of native to non-native plants and how the presence of clover affects that ratio. Differences in the ratios may tell us if clover does indeed harm plant communities indirectly. To complement what is seen in the field, we set up a greenhouse experiment with three soil treatments and four litter treatments, one of which is clover. Either yellow wood sorrel, a native wildflower, or sheep sorrel, an invasive flower, is grown in the treatment pots. How well each plant grows in the different treatments coupled with the field data should tell the story of cow grazing and plant community dynamics.

At the halfway point of the summer, what story the data will tell is still uncertain. One certainty, though, is that amidst the ecological research, weekend adventures, and the new set of friends, I found a piece of home where the cows roam.

 Jerilyn Calaor is a rising senior at the University of Guam studying Biology with a minor in Chemistry