Student Spotlight

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Graduate Student Jenny Shrum Studies Sugar Maple Sap Flow in Northeast

Graduate student Jenny Shrum is as excited as ever to start her new project on maple trees this spring. She is interested in the role of sugar maples in the Northeast and is examining how climate change may shape this role. The first part of her study explores the plausibility of using traits expressed at the edge of a species’ range to help cope with climate change. In the case of sugar maples, she is interested in finding out if trees from other regions might actually be better suited to the conditions Maine will be experiencing in fifty years. If so, foresters and syrup producers may be able to plan sugar maple seeds from those regions here. Many people think that tree species exist here because they are best adapted to this environment, but that’s not always the case. “We might be able to utilize specific characteristics adapted by a certain subpopulation to help a forest or sugar bush to thrive despite climate change.”  The second part of her study will try to draw correlations between sap flow and weather conditions to better understand how the sugaring season is likely to be affected as the severity, length, and timing of winter changes in the decades to come.

Shrum is a Ph.D. candidate in the Graduate Program in Ecology and Environmental Sciences and is working under SBE professor Brian McGill. Her dissertation will include planting different populations of sugar maple seeds from across the range in a common garden and comparing the rate of germination and seedling growth success. With a little luck, she hopes to find a successful tree that perhaps can be tapped for syrup in later years. Unfortunately Shrum won’t be able to tap the trees before her Ph.D. program is over. “It takes 20 years before you can tap a tree,” she said. However there may be people able to continue the study.

Shrum has found several citizens that have been tapping trees for many years, and they may be able to give insight into maple syrup production in the past and future. “One man said he doesn’t see sugar maples reproducing like he used to, and now he has to plant them himself,” she said. “Another man has been collecting soil temperature in his yard at two feet deep for the last 20 years. I can use this data to correlate temperature and snow cover to sap flow.” After talking to citizens it is clear to Shrum that maple trees provide a certain role in New England culture and are very important to the people of Maine.

Before coming to UMaine, Shrum was working on numerous wildlife ecology projects over a span of fifteen years, but she is enjoying working with maple trees even more. “I wanted to study something that had ecological, economic and social importance. This is something that families have been doing for years and I hope this research will be meaningful and help someone along the way,” she said. Best of luck to Jenny Shrum as she continues her research. Shrum is producing a short video about her research that will be available on the SBE website by mid summer.

Courtney Wigdahl

Courtney Wigdahl began studying limnology with Jasmine Saros as an undergrad at the University of Wisconsin – La Crosse. Now, a Ph.D. student in Ecology and Environmental Science and still working with Saros, Wigdahl combines her background in biology and ecology with the resources of the Climate Change Institute. Wigdahl studies salinity variation in salt lakes in the Great Plains via lake sediment records, focusing on a special type of algae called diatoms. That diatoms are especially sensitive to changes in water quality and other climate variables makes them a prime indicator used by paleolimnologists in reconstructing climate records. But reconstruction alone often poses more new questions than it answers, and Wigdahl plans to investigate the contradictions evident in diatom-reconstructed salinity records.

This summer Wigdahl will travel to North Dakota to collect lake cores, which will be supplemented by experiments in Saros’ lab in Orono. Eventually, Wigdahl will use the ecological interactions among zooplankton, vegetation, and algae to assist in interpreting diatom-inferred salinity, and ultimately her findings will contribute to climate change data for the region.

The existing instrumental climate record for the Great Plains, the ‘bread basket’ of the country, extends only to the past fifty to one hundred years. Drought patterns in this region, including the devastation of the Dust Bowl in the 1930s, have profound economical implications for region and the country.

Wighalh’s affiliation with both the School of Biology and Ecology and the Climate Change Institute enables her emerging work that blends paleolimnology with modern ecology. In this approach, Wigdahl benefits from field and experimental data, and can test hypotheses of one dataset against the other. The combination of both offers a more complete ecological picture. In addition to her work in Great Plains precipitation patterns, Wigdahl will travel to Chile next year with colleagues in the Climate Change Institute to assist in South American lake core analysis.

Wigdahl began at the University of Maine in 2007. After the completion of her dissertation, Wigdahl plans to continue salt lake research and hopes to start engaging undergrads in fieldwork and research.

Chris Tonra

Chris Tonra has been a lover of wild birds since the age of 12 growing up on Long Island, NY. This fascination with birds led Chris to pursue a career in ornithology, eventually receiving a Masters of Science in Wildlife Ecology from Humboldt State University in California. During his time in California, Chris became interested in how birds interact with their habitats and how these habitats may limit the fitness of individuals. This ultimately brought Chris to the doctoral program in Biological Sciences at UMaine and the Lab of Avian Biology, led by Dr. Rebecca Holberton.

Migratory birds interact with multiple habitats throughout their life cycle, sometimes spanning thousands of miles between tropical wintering grounds and temperate breeding grounds. Along with Dr. Holberton and his co-advisor, Dr. Peter Marra of the Smithsonian Institution’s Migratory Bird Center, Chris has been conducting a study examining the mechanisms by which conditions in tropical wintering habitats of migratory songbirds carry-over to limit reproductive success in the temperate zone, primarily focusing on the American Redstart. Chris has been conducting fieldwork both on the wintering grounds in Jamaica, West Indies and on the breeding grounds at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. His project has utilized both experimental and observational studies of captive and wild birds to determine how male songbirds balance the enormous feat of migrating thousands of miles in spring with the equally demanding task of undergoing a dramatic physiological transition from a non-breeding to a breeding state. This work utilizes various tools to examine songbird physiology by both measuring natural levels of breeding hormones and experimentally manipulating hormone levels. Chris is also using stable-isotope analysis of various bird tissues. This tool uses predictable geographic patterns in different forms of the elements carbon and hydrogen to gain information about where birds have been and even where they are going.

Thus far Chris’ work has demonstrated that the timing and magnitude of testosterone release in males prior to arrival at breeding areas is an important driving factor in the phenology of migration. This is an important finding as the timing of arrival at the breeding grounds is a key driver of individual fitness in migratory birds. He has also demonstrated that the condition that birds are in prior to departing tropical wintering grounds is not only correlated with winter habitat quality, but also with breeding hormone levels prior to spring departure. It appears that, much like athletes’ use of androgens, such as testosterone, enhances their performance at their sport, male birds may utilize these same chemicals to enhance their performance in migration.

Chris has received a National Science Foundation Dissertation Improvement Grant and a fellowship from the Smithsonian to support the final year of his doctoral work at the National Zoo in Washington, D.C. During his time there, Chris will continue to examine these questions and expand upon them by including data collected from other species of birds during migration. This work is part of an ongoing effort by a number of ecologists to better understand how and where migratory bird populations are limited, such that those managing these populations can focus on “full life-cycle stewardship” to more effectively ensure population persistence. Upon completion of his doctoral work, Chris plans to continue working on carry-over effects in migratory animals by expanding these ideas to other taxonomic groups, such as migratory mammals and amphibians.

Allison Byrd

Allie Byrd was fascinated by the natural world at a young age and her interest in wildlife lead her to pursue a B.S. degree in Wildlife Biology at the University of Rhode Island. Upon graduation, Allie worked on research projects with numerous species ranging from black bears to brook trout, but a field job in Australia got her hooked on bird research. Subsequent avian positions allowed Allie to research various species across the globe. After gaining experience in the field, Allie decided she would like to implement a study of her own and began her Master’s work with Dr. Brian Olsen at the University of Maine.

The primary goals of Allie’s research are to understand the vulnerability of New England’s common loon (Gavia immer) to climatic change and to use this information to suggest current and future management actions. Over the next century, expected changes to freshwater ecosystems include increased amount and variability of precipitation, increased lake level fluctuation, earlier spring run-off, and extended drought periods. Effective and appropriately prioritized conservation actions in an era of changing climate require accurate, predictive models of the demographic mechanisms behind range contraction and expansion.

Allie’s project will combine demographic analysis, physiological measures, and behavioral observations across a range of climatic conditions to predict how future alterations to lake characteristics may impact loon distributions. The results of this study will contribute to the demographic model of the common loon which will predict the conditions under which Maine is likely to lose this iconic species. This information is critical for their conservation and continues the University of Maine’s long tradition of managing the state’s natural resources.

Allie began her M.S. at the University of Maine in 2009. After the completion of her thesis, Allie plans to continue avian research and hopes to effect change through work with a non-profit agency.