A walk in the woods renews and recharges. Renews my sense of place and recharges my efforts to continue my work in sustainability. A trip to the Harvard Forest offered a walk in the woods I had never experienced.
Located in northern central Massachusetts, the Harvard Forest covers 4,000 acres. It was established in 1907 and is a department of the Faculty of Arts and Sciences (FAS) of Harvard University. Research facilities and the Fisher Museum are used by scientists, students, and collaborators at the Forest to explore topics ranging from conservation and environmental change to land-use history and the ways in which physical, biological and human systems interact to change our earth.
As part of Harvard’s Climate Action Week this past June, attendees were offered the 75 minute ride to the Forest for a day of hiking and learning. I was one of those attendees who made the trip.
Of the 32 miles of trails, our tour hiked three of them. The scientists who worked in the Forest doubled as our tour guides. They helped us view the forest as a living, breathing organism that serves as a laboratory for experiments to study the current and future effects of climate change.
We stopped to see marked trees that were part of an ongoing experiment where each tree’s diameter was measured every few years to determine growth rates of various tree species over time. Over 100,000 trees are part of the experiment.
Another parcel of land just off the main trail revealed an artificially heated plot of land to mimic how tress and ground fauna in the northeast might react to warmer ground temperatures.
Our final trail stop was a fire tower lookout. The tower stretches 92 feet and extends above the canopy of the forest. The platform at the top offers’ spectacular views and unique research opportunities.
Five different towers are sprinkled throughout the Harvard Forest. The towers offer a wide array of research opportunities such as measuring carbon dioxide and other atmospheric trace gases (e.g. methane and other hydrocarbons, nitrogen oxides, and ozone), above canopy research, wind, temperature, relative humidity, and light measurements.
For me, the experience of hiking has always been about what is lush, green and living. As we walked and talked with our scientist guides, they brought attention to what was dying. The hemlock trees are dying.
The Eastern hemlock is a foundation species in the eastern United States and plays a critical role in the local biota. The hemlock deeply shades the soil, creating a unique microclimate for some species. The elegant and monstrous tree can grow to 100 feet tall and live as long as 800 years. Eastern hemlocks grow on 19 million acres in the eastern United States and are the dominant tree species on 2.3 million acres. The hemlocks dot the forest landscape from the Southern Appalachians to Maine and west to Minnesota. Why they are dying revealed the interconnectedness, unseen effects and complexity of climate change.
The invasive woolly adelgid, a non-native phloem-feeding insect, is killing hemlocks. Brought to America from Asia in 1950’s, the insects insert their feeding tube into the cells of the hemlock needles and feed on carbohydrates, eventually starving the hemlocks of their energy supply.
The woolly adelgid is sensitive to cold winter temperatures. Low temperatures in the range of minus 10 degrees F will kill most of the insects. The combination of climate change causing milder winters and the invasive insects’ ability to adapt to colder temperatures over time has proven to be a death nail for the hemlock. The insects march northward is only stopped by consistent cold temperatures in the winter months.
What does dying hemlocks mean for climate change?
Hemlocks are being replaced by hardwood forests that are resistant to the pest. The replacement trees have less shade which changes the environment for plants, animals and insects reliant on the protective hemlock. Mature hardwoods that will replace the hemlocks are predicted to capture as much carbon as the hemlock but that is at least 40 to 50 years from now when the hardwoods fully mature.
The hemlock is dying much quicker than the hardwoods will grow. When trees die, the carbon capture role of trees is reversed. The carbon dioxide stored in the wood is slowly released into the atmosphere. As the dying hemlocks release carbon, the new trees that will naturally replace the hemlocks are not grown enough to absorb the dead hemlock’s carbon release nor the former living hemlock’s absorption rate.
Thus, we are adding more carbon to the natural environment. A Harvard study showed that woolly adelgid could take an 8 percent bite out of northeastern forests’ carbon sequestering capabilities in the years to come.
The carbon absorption reduction is caused by a cocktail of an invasive species mixed with a foundational tree species of the eastern United Sates forest with a heavy shot of climate change.
This is just one invasive pest affecting one tree type in one part of the world.
My mind races to the bigger picture. This story cannot be unique. How is climate change affecting other tress foundational to their native lands like the Ceiba Trees in the rainforests of the Amazon, Scots Pine in Germany, the Katsura Tree in China or the Bottle Tree in Australia.
I don’t know and as our trip to the Harvard Forest came to an end, neither did the scientists.
“We don’t know” was a common answer to bigger picture questions posed by our tour group. Scientists continue to study the forest to find answers. They finished by stating “There is a lot of interacting factors. The Forest helps us better understand the combination of those factors.”
As we boarded the bus to travel back to the university, I was encouraged and motivated. Encouraged by the ongoing scientific work being done at places like the Harvard Forest. Motivated to continue my sustainability work in witnessing the layered and often unseen effects of climate change.
Encouraged and motivated.
Renewed and recharged.
A walk in the woods.