Thursday, October 26, 2017

Wildflowers on the Charles River

Posted by Richard B. Primack

“There is just as much beauty visible in the landscape as we are prepared to appreciate.” 
-Thoreau in Autumnal Tints

The Charles River is a natural history treasure for the people of Boston. In July, my son Dan and I went kayaking and observed the most astonishing display of rose mallow plants flowering along the banks of the Charles in West Roxbury, Dedham, and Needham. There were thousands of gigantic plants, many of them with dozens of 6 to 10 foot tall stems, and covered with huge saucer sized pink blossoms. The most impressive display of flowers was on an island in the Motley Pond region of the river. 

Tall multi-stemmed rose mallow plants along the banks of the Charles

Flowers of rose mallow are astonishingly large

Large patches of dying purple loosestrife plants could also be seen along the river. This beautiful European ornamental plant has been an aggressive wetland invader over the past 4 decades, out-competing native species. In recent years, European beetles that specialize on purple loosestrife have been released as a biological control program. And by the looks of these highly damaged plants, the beetles have won the fight. 

Stands of purple loosestrife turning brown with damage

Beetles have damaged this purple loosestrife plant

Monday, October 23, 2017

Coring the Past

posted by Caitlin McDonough MacKenzie

“I live in the present.  I only remember the past – and anticipate the future.”
 Thoreau in his Correspondence.  1848.

Last month I returned to my dissertation research site at Acadia National Park. But instead of hiking the ridge of Sargent Mountain to record this year’s flowering and leafing times, I plumbed the depths of Sargent Mountain Pond for evidence of past plant life that once fringed the granite kettle hole. I’ve traded historical ecology for paleoecology, and in my new postdoc position in Jacquelyn Gill’s BEAST (Biodiversity & Environments Across Space and Time) lab, I will focus on pollen grains trapped in ancient lake sediments.

Coring Sargent Mountain Pond: Caitlin pushes the corer into the lake sediment below the raft while Jacquelyn ties off the cable connected to the corer's piston.

I timed this fieldwork to coincide with a Sierra Club project: all week a group of Sierra Club members volunteered in Acadia. On Tuesday, they joined me and the BEAST lab as we hauled coring equipment — including giant inflatable pontoons and two 4x8’ plywood deck pieces — up to Sargent Mountain Pond. We carried in giant inflatable pontoons for a raft and two 4x8’ plywood decks: a major feat on a challenging trail. We hiked it all in, assembled the raft and inflated a kayak, and then launched our floating field site on to the pond. From our raft, we extracted cores of sediment from the deepest basin of the pond — over 11 feet deep — using a piston corer. The piston corer allows us to push deep into the lake bottom and pull up 1 m of sediment in each drive. Over the course of three days we cored nearly 9 meters of sediment. These cores represent a journey through over 4 meters of organic material under Sargent Mountain Pond, into the grey sands of a glacial landscape. We cored 4 meters deep twice: two overlapping records will give us a continuous chronicle of pollen through the last 15,000 years.
Caitlin celebrates with her first core!

We cored Sargent Mountain Pond because it sits just below treeline in Acadia and subalpine plant communities grow at its edge. As the Laurentide ice sheet retreated, Sargent Mountain Pond emerged as the “first pond in Maine”; the rest of its limnological siblings were under still ice. Previous coring research at Sargent Mountain Pond has confirmed this and sediments in the basin are over 16,000 years old.

The pollen trapped in the pond’s sediments will help us to answer questions about the history of the subalpine plant communities around Sargent Mountain Pond. How dynamic is treeline on Acadia’s granite ridges? Have Mount Desert Island’s subalpine communities persisted here since the last ice age? How have these species responded to past climatic changes?

It was lovely to be back in Acadia for fieldwork and I’m looking forward to splitting open our cores to study the long ecological history of this site.

Sunday, October 1, 2017

Swimming (Illegally?) in Crystal Lake

Posted by Richard B. Primack

“Unjust laws exist: shall we be content to obey them, or shall we endeavor to amend them, and obey them until we have succeeded, or shall we transgress them at once?” 
-Thoreau in Resistance to Civil Government

It is a hot summer day, and dozens of young people and families with children are enjoying swimming and wading in the two coves of Crystal Lake in Newton Center. All this is taking place in areas with large, clearly posted “No Swimming” signs, and warnings that swimmers can be arrested for trespassing. What exactly is going on? In a recent issue of the Newton Tab, I address this topic.

For decades, Newton residents have enjoyed safe swimming in the lifeguard-supervised area of Crystal Lake. But over the last six years, adults and children have increasingly been swimming illegally in the nearby coves. The advantages of swimming in these areas are obvious: they are quiet, with a relative lack of crowds, they are available when the official swimming area is closed, there are no restrictions on food and drinks, and there's no need to pay for a permit.

Signs posted at Crystal Lake clearly state swimming is not allowed

In 2012, some Newton residents petitioned the city to allow swimming at your own risk in the coves; similar policies are in place at Walden Pond State Park in Concord. But the Newton government was unwilling to allow cove swimming and it remains illegal. Enforcement by police, however, is weak or nonexistent.

What are the main arguments against allowing swimming in the coves? First, swimming in the coves violates posted regulations, so it might contribute to disrespect for the law. Second, there are no lifeguards, and the city might be liable for injuries and drowning. And third, noise and parked cars disturb some local residents.

Thus far, the city and residents have been unable to develop a consensus solution to deal with cove swimming. Such a consensus would include policies that enhance swimming opportunities, swimming safety, residents’ rights, and the lake’s health. This is easier said than done, but it provides a goal to work toward. If Thoreau were around today, what would be his advice? Transgress unreasonable laws? Or head into the woods and avoid the crowds?