Monday, November 13, 2017

An International Network of Trees, published in Silva

Posted by Amanda Gallinat

"Nothing makes the earth seem so spacious as to have friends at a distance; they make the latitudes and longitudes" -Thoreau in a letter, May 22, 1832

For the last five years, the Primack Lab has been part of a collaborative effort to monitor leaf-out, leaf senescence, and fruiting times at a network of seven international botanical gardens. We recently published an overview of this collaborative work in the Arnold Arboretum's magazine, Silva

Richard Primack carefully monitors leaf senescence at the Arnold Arboretum

In the article, we describe how the living collections of botanical gardens have allowed us to monitor the phenology of an enormous range of species; with our colleagues, we have monitored >1600 species for leaf-out, 1360 species for leaf senescence, and several hundred species for fruiting. Our lab conducts our observations right here in Boston, MA, at the Arnold Arboretum.

Young leaves of Acer japonicum observed on April 24th at the Arnold Arboretum

The group's observations across botanical gardens and years have demonstrated that species leaf-out and fruit in a consistent order from year to year and place to place (and related species have similar timing), while the order in which species change color and drop their leaves is not consistent across space and time.

I record fruiting times for plants in the vast Viburnum collection at the Arnold Arboretum

Uncovering these and other patterns in the spring and autumn phenology of many species has given us new insight into the rich natural history present at the Arnold Arboretum (our home site) and other botanical gardens, and helps us understand how plant schedules will respond to climate change.

Wednesday, November 8, 2017

Humidity does not appear to trigger leaf out in woody plants

Posted by Lucy Zipf

Leaf-out phenology in woody trees and shrubs is considered to be strongly controlled by a combination of spring warming, winter chilling requirement, and photoperiod. In 2014 researchers suggested that humidity, rather than temperature itself, might be also be a main trigger of the spring leaf-out of woody plants – with plants leafing out earlier in higher humidity environments. We tested this hypothesis in our recent paper titled “Humidity does not appear to trigger leaf-out in woody plants.”


Gathering dormant twigs from the Hammond Woods in Newton, MA 

We gathered dormant twigs from 15 species of woody plants and exposed twigs from each species to four humidities ranging from 20% to 94% relative humidity. We then monitored the twigs daily for a month to see if twigs in higher humidity treatments leafed out before those exposed to lower humidities.


Twigs of the 15 study species in the highest humidity treatment halfway through the experiment 

The title of the paper gives away our main result: We did not find any consistent, measurable effect of high humidity advancing leaf-out. We also did not see patterns of progressively earlier leaf-out in successively higher humidities. Given our results, humidity does not appear to be a determinant of spring leaf-out in these New England plants.

Late Autumn Colors

Posted by Richard B. Primack

“Live in each season as it passes - breathe the air, drink the drink, taste the fruit & resign yourself to the influence of each.” -Thoreau, in his Journal, 1835

During the past 100 years as global temperatures have risen, the date of the first autumn frost has gotten a week or more later, as reported in an Associated Press story by Seth Borenstein, entitled "Science says: Jack Frost nipping at your nose ever later". Late autumn frosts combined with early springs result in a growing season that is now several weeks longer in much of the United States. This year’s warm October temperatures have delayed Boston’s autumn, with night-time temperatures above freezing through November 1. Across the northeastern United States, the mild weather has held back the the vibrant leaf colors associated with the autumn season, as described the Popular Science article, "Where the heck is autumn?" by Rachel Feltman. 

At the end of October, our Newton garden was still green and productive (photo by Margaret Primack)

As November begins, many trees and shrubs in the Boston area are still covered with green leaves, many ornamental plants are still flowering, and bees and butterflies are still flying. Closer to home in our garden in Newton, we are still harvesting tomatoes, lettuce and other salad greens, parsley, beans, and zucchinis as November starts. Most surprisingly, we are eating fresh figs every day from our fig trees. We are in eastern Massachusetts, but the weather and the season seem like somewhere hundreds of miles to the south.

We are still harvesting tomatoes from our garden in early November 

Friday, November 3, 2017

Last Days at Biological Conservation

Posted by Richard B. Primack


“Men do not fail commonly for want of knowledge, but for want of prudence to give wisdom the preference.” 
-Thoreau, A Week on the Concord and Merrimack

After nine years, I recently stepped down as Editor in Chief of Biological Conservation. I supervised a team of 9 Editors, handling over 14,000 submissions, and eventually publishing over 3,000 articles that advanced our knowledge and provided practical value for people protecting biodiversity in the field and developing policy. 

In this staged photograph, four co-authors are having a disagreement; in one Biological Conservation editorial, my co-authors and I describe problems co-authors can encounter, and provide some recommendations for happy co-author relationships

We published many Special Issues on topics of current interest. For example, articles in the special issue on environmental DNA showed that the presence of rare species and newly arrived invasive species in lake or river could be detected from a few molecules of DNA in small water sample. And our Citizen Science issue described how to work with networks of volunteers in conservation projects. 

We examined the editorial process of the journal, finding there was no bias in acceptance rates of papers submitted by female authors, though individual editors had different acceptance rates. We learned that Chinese and Indian scientists often worked on weekends, Japanese and Mexican scientists often worked at night, and European scientists tended to work typical office hours. We evaluated how reviewer recommendations affected acceptance rates, and determined that a “Reject” review was like the “kiss of death.” And finally, we described problems that co-authors sometimes encounter in working together, and provided constructive suggestions for co-authors. 

This confused editor tries to make a decision based on four very different reviews! In fact, our analysis showed that reviews tend to be consistent from reviewer to reviewer

As Editor in Chief, I always tried to recognize that authors needed to be treated as individuals, and in many cases I could assist them with particular issues. We helped many young scientists to publish their first paper in an international journal, and establish their careers. In the end, we were able to create a community of authors, reviewers, editors, and readers, who could cooperate to advance our knowledge in the field of conservation biology.

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?