“Reconstructing Landscape Change in New England from Lake Sediments: Interaction of Humans, Vegetation, Climate Change, and Extreme Weather”
The Harvard Forest provides undergraduate students with an incredible interdisciplinary experience that emphasizes community, responsibility, and personal accountability while supporting students through their educational experience. Reflecting on the experience, Turtle McCloskey said, “Every aspect of the program, from the weekly R workshops, to helping cook dinner for the entire cohort of REU students, was incredibly beneficial and helped me grow as a student, a scientist, and a person.”
Written by Turtle McCloskey; Fall 2019
I was fortunate enough to spend this past summer working as a research intern at the Harvard Forest in Massachusetts. I was working on a large-scale research project titled Reconstructing landscape change in New England from lake sediments: interaction of humans, vegetation, climate change, and extreme weather.
Our research team collected sediment cores from a variety of post-glacial lakes in the New England region and utilized a variety of analysis methods to try and quantify landscape responses to anthropogenic disturbances and climate change. Under this broad umbrella I needed to design a small-scale, focused research project that I could complete in 11 weeks. I decided to center my research around a dialogue addressing the ways we can observe the lasting impacts of settler colonialism in New England. In my analysis of sediment cores, I examined how disturbances to the land caused by Euro-American settlement and the associated forced displacement of Indigenous Peoples could be observed through sediment core chronology. I studied the sediment cores for my project utilizing a variety of analysis methods, and then analyzed and visually represented my data using R. I also used ArcGIS to create maps of the area from which my cores were taken and performed advanced analysis of the watershed and surrounding landscape using ArcGIS. In addition to the specific tasks associated with my own project, I also helped my research partner Tania with her project, helped collect sediment cores from various lakes in New England for the larger project, and analyzed various sediment cores to support the larger project. I also helped with various daily tasks to help with the larger project.
Through this research experience I learned a plethora of valuable skills. I gained extensive knowledge of the geology, hydrology, ecology, and history of the New England landscape. For instance, there are almost no old-growth forests in the region. While much of the landscape is heavily forested, most of the trees are less than 100 years old, due to large scale land clearing practices throughout the 18th and 19th centuries and then a strong reforestation effort in the 20th century. Short stone walls can be found throughout much of the forest landscape. I learned that these stone walls are there because when settlers started clearing land for agriculture and livestock grazing in the 18th and 19th centuries, the soil was filled with rocks that had to be removed, so farmers would move all the rocks to the edge of their fields and then use the rocks to build stone walls to demarcate their property. These stone walls are so prevalent that there is an online data layer in ArcGIS mapping stone walls in New England. I actually ended up using these stone walls in my GIS analysis of land use changes in the region, because even if the stone walls are not already mapped, they can be seen in using the hill shade feature of ArcGIS, which provides information about the land use history of a given area.
I learned specific data collection methods related to sediment core analysis, such has how to perform Loss on Ignition analysis (LOI), pollen grain analysis, and Carbon-Nitrogen ratio analysis. LOI serves as a proxy for the total organic carbon in sediment and involves sampling at 1cm intervals across the length of a core, baking the samples, and then putting the samples in a furnace until all of the organic matter is burned off and only the inorganic matter is left. Pollen grain analysis allows you to see what types of plants were around at different points in time. Carbon-Nitrogen ratio analysis can be used to show changes in types of organic matter (terrestrial or aquatic) at different points in time.
Sediment cores can provide a historic record of all kinds of changes, but in order to interpret results with respect to time, age-depth modeling is needed. After using radio-carbon dating to establish ages of macro-fossils sampled at different depths in my cores, I learned to make an age-depth model using the clam package in R. With this model, I could interpret changes in the sediment at various depths across a time interval. I learned to write scripts in R (an open-source data analysis software program) in order to represent my data in beautiful figures. This was incredibly difficult for me at first, and there was quite a learning curve, but eventually I grew very skilled and was able to produce beautiful graphs and figures.
I learned to analyze changes in land use using historical aerial photographs and Geographic Information Systems Software, and how to create bathymetric maps using sonar coordinates from a fish finder and ArcGIS. Both of these tasks were challenging, because while I had taken Maps, Cartography, and Geospatial Technology, I entered the program only knowing the basics of ArcGIS. My mentors were happy to help me if I had questions, but I mostly had to out how to do these tasks in ArcGIS on my own. Through this process I became incredibly skilled at using ArcGIS and I now feel confident in my GIS abilities.
In addition to these many valuable skills specific to my research, the Harvard Forest REU program also provided a variety of professional development workshops and weekly seminars from various professionals in the environmental science field. The workshops helped me learn how to write research proposals to the National Science Foundation standard, how to give an effective poster presentation, how to apply to graduate school, how to effectively communicate in science, and more. The weekly seminars not only helped me gain insight into the various career opportunities and fields of research available to me, but they also allowed me to make connections with scientists from across the country. These seminars occur weekly in the evening after dinner, but the guest speakers always had dinner with the REU students. This allowed me to sit with various guest speakers during the meal, which helped me make personal connections with guest speakers and ask questions about various aspects of their professional journey. Unrelated to my educational and professional development, I also became certified to drive a 12-passenger van (with two canoes on top), and learned how to change the oil in a car.
I feel incredibly blessed to have been a part of this phenomenal undergraduate research program. The Harvard Forest provides undergraduate students with an incredible interdisciplinary experience that emphasizes community, responsibility, and personal accountability while supporting students through their educational experience. Every aspect of the program, from the weekly R workshops, to helping cook dinner for the entire cohort of REU students, was incredibly beneficial and helped me grow as a student, a scientist, and a person.