On Monday Oct. 6, Mark Green, a professor of hydrology, the study of water, at Plymouth State University came to Keene State College to discuss the resilience of New Hampshire watersheds and their recovery from historic disturbances. He began by discussing a 500-year challenge, the objective to improve watersheds in the Northeast and dove deep into the importance of New Hampshire residents’ understanding of such.
After finishing his Ph.D, Green explained, he was asked to join a project linking humans and water in the Northeast.
“I saw this position to delve into the human history and tie it to hydrology and it just seemed so incredibly novel that I couldn’t pass it up,” Green said.
It was a large effort, according to Green, as a national science foundation joined with the consorting of universities for the advancement of hydrologic science.
Green began his lecture by introducing maps from the 1600s that showed the expansion of communities along the Northeast.
Supported by a graph, Green said the population began to flourish in the year of 1795 and the river corridors became heavily populated as they were the transportation methods at that time.
The broadest concern about the idea of improving watersheds, according to Green, was what the people were doing to the landscape. Green informed the audience that as the population increased, deforestation became more abundant.
Green said it is important for scientists to understand how water is moving through the landscape but it is hard to look at past data, as the way of keeping records was not as efficient as it is now.
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Green continued to tell the audience that his first meeting with the scientists involved with this project was at Tufts University in October of 2007.
He shared that he was compelled to dig deeper into the project since he was not from the Northeast and was anxious to learn more about its watersheds.
“The team of people that were doing the work, it was so compelling, I thought, ‘Alright, let’s get out of our comfort zone and move to New England,’” Green added.
Green said his motivation was from the hypothesis that European settlement and the change to the forests that occurred had temporary changes in hydrology that were so short-lived, that they may be difficult to detect.
He dappled into his abroad studies at the University of Tokyo where he told the audience he worked with scientists for a year to try and formulate a correct definition for the type of resilience they were studying.
To get a better understanding of the subject, Green assured the audience that resilience is the ability to absorb disturbance (an event that disrupts an ecosystem structure) and maintain quickly to regain hydrologic function.
He continued about the importance of the hydrologic function and the factors that can change the vegetation, such as transpiration losses that will cause changes in soil water.
According to Green, the most important factor to a hydrologist is how much water is leaving the watershed by river-flow.
As a research hydrologist at Hubbard Brook Experimental Forrest since 2009, Green focused on his study of six watersheds south facing on the north end of a valley in the Northeast. He focused on three types of experiments: forest harvesting, measuring precipitation and climate variability.
Green said he studied many questions of forest harvesting. One being: what happens to water quality after a forest is harvested?
For this experiment, Green informed the audience that scientists cut down trees in a forest but did not remove them from the ground.
After leaving a material on the ground for three years, this ongoing experiment showed that the material had degraded.
Another question, Green said, was much more practical. In a different watershed, the scientists came up with a way to take biomass out of watersheds without inducing a spike in water run-off or nitrogen loss from the system.
In 1970, scientists took strips of the watershed to be harvested and Green said the hydrologic response was that the watershed that had been harvested had an additional 370 ML of water that flowed out of it, compared to the one that hadn’t been harvested.
The next focus of the lecture was erosion. Green said he wondered if the flooding would have happened if the forest were intact.
By managing forests, it changes water flow reports, but this one-year study showed that there was no evidence that forest management was causing major changes.
The study also showed that erosion was less of an issue of deforestation.
In Green’s conclusion, he assured that he and fellow scientists have plenty of evidence from Hubbard Brook as well as modeling exercises and measurement records that suggest the resilience hypothesis stands.
He projected his ideas and said that climate is a driver of annual run-off rather than land use, because America is undergoing more climate change which, according to Green, is causing history in the hydrologic records.
Green said scientists still do not understand why this system is resilient as they need more mechanisms and to understand just how generalizable the results are. He said he is questioning the system as the temperature and precipitation increase, what implications will make the system better?
Green concluded by saying their main focus is maintaining resilience and not taking the system for granted.
Green enlightened the audience with the knowledge that most of this research had been done with graduate students.
“I was really interested in engaging students in this,” Green said. He added that some students worked inside doing research and others worked by communicating with a non-scientific audience.
Kaleigh Cyr, a senior at KSC, attended Green’s lecture for an extra-credit assignment.
Although she did not know what to expect, Cyr said she was drawn to the topic as she is from the White Mountains [the focal point of experiments], so the subject was very local to her.
“I’m really into history, so that aspect of the talk really made it more interesting,” Cyr said.
Green was introduced by colleague Denise Burchsted, a graduate teaching lectures of environmental science at Plymouth State University.
Burchsted informed us of his past education of biology in Minnesota and earning his master’s degree at the University of Nevada.
Burchsted also went on to inform the audience of Green’s opportunity presented by the University of New Hampshire to study watersheds in the state of New Hampshire.
Burchsted explained that both she and Green “share a strong interest in understanding the history of [our] landscape, especially the river network.” She continued to say the duo love to “use the past to interpret the present,” as their studies not only focus on watersheds today, but how they came to be.
Joy Ackerman, a professor at Antioch University New England graduate school, also attended the lecture as a colleague of Burchsted’s. “One of my graduate students is working with her and her undergraduate students so we try to support each other’s talks.”
Ackerman continued, “These lectures are a nice way to keep up on what research is going on in this area and instead of reading papers you can come talk to the people who are doing the research.”
Green said he hopes he can give lectures in the future not only at colleges or universities, but possibly historical societies or local libraries to get more people engaged in the subject.
He said he is excited that somebody that is into the history of hydrology might learn more about the science by “simply looking at it from a historical aspect.”
MacKenzie Clarke can be contacted at mclarke@keene-equinox.com
