Temperature at the bottom of Walden Pond

Posted by Richard B. Primack

On August 22, 1860, Henry David Thoreau measured the temperature at the bottom of Walden Pond, one hundred feet below the surface. In his journal, he describes lowering a bottle of water on a line and leaving it there for thirty minutes. Hauling the bottle up, he used a thermometer to measure a water temperature of 53 degrees, which was 22 degrees lower than the surface. This range of temperatures surprised him:

What various temperatures, then, the fishes of this pond can enjoy! They require no other refrigeration than their deeps afford. They can in a few minutes sink to winter or rise to summer. How much this varied temperature must have to do with the distribution of the fishes in it. The few trout must oftenest go down below in summer.

On August 23 of this year I repeated Thoreau’s measurement. My son Jasper, our friend Ariel, and I paddled a canoe out to the deepest spot in the middle of Walden, using Thoreau’s 1846 map as a guide. The air temperature in the Boston metropolitan area has risen by about 4 to 5 degrees since Thoreau’s time, and the ice on Walden is now melting two weeks earlier in the early spring. Would the temperature on the bottom of Walden still be 53 degrees, or is it now warmer due to climate change?

At the middle of Walden, we lowered three bottles into the water on a weighted line:  a hot one at 109 degrees, a cold one at 55 degrees, and one filled with lake water at 78 degrees. Would they all be the same temperature after 30 minutes on the bottom? The weighted line took the bottles down to a depth of exactly 100 feet.

Lowering bottles into Walden Pond on a weighted line. Photo by Ariel Chua. 

After 30 minutes, we hauled up the bottles. The lake water bottle and the cold water bottle each measured 50 degrees, a bit colder than Thoreau’s measurement of 53 degrees. The hot water bottle measured 52 degrees; was it hotter because it started hotter?  A re-measurement of the lake water bottle showed 54 degrees; it had gained 4 degrees in 4 minutes from the surrounding 76-degree air.  In our case, we were using a fast electronic thermometer that took only seconds for a reading, whereas Thoreau was using a slow mercury thermometer that would have taken several minutes. So our first slightly colder temperature reading was probably just due to our ability to measure the temperature more quickly than Thoreau had before the water had warmed up by a few degrees.

After 153 years, the bottom of Walden Pond is still a cold place for fishes, and has changed little since the time of Thoreau. The great depth of Walden Pond has apparently insulated the bottom from the changes above, at least for now. 

Do scientists work too hard?

Posted by Richard Primack

It would be glorious to see mankind at leisure for once. It is nothing but
work, work, work. I think that there is nothing, not even crime, more
opposed to poetry, to philosophy, ay, to life itself, than this incessant
business.    -Henry David Thoreau

Thoreau thought that people worked too hard, and did not have enough time to devote to the really important things in life. To find out how hard scientists are working now, my colleagues Ahimsa Campos-Arceiz, Lian Pin Koh and I analyzed the day and time of submission for 10,000 manuscript submissions and almost 15,000 reviews sent to the scientific journal Biological Conservation. 

 Ahimsa Campos-Arceiz, one of the authors of the study, reviewing a manuscript while traveling to a field site in Malaysia.

Our results showed that these scientists do a substantial amount of their work late at night (16% of the manuscripts) and on weekends (11% of the manuscripts and 12% of the reviews); and that this work outside of normal hours has been increasing at about 5-6% per year. Japanese and Mexican scientists stood out for working late at night and Chinese and Indian scientists worked far more than average on weekends.  In contrast, Belgian and Norwegian scientists did not work much on weekends, and Finnish scientists did not work at night. American and British scientists had average work habits, working moderate amounts on weekends and evenings. 

Overall this study shows that conservation biologists and potentially other scientists and academics do a considerable amount of their work outside of what we generally consider regular working hours.  This can negatively affect the scientists’ life-work balance, impacting relationships with family and friends, physical exercise, or just resting time. However, is it possible that conservation biologists just enjoy what they are doing and for them it is not all work. After all, Thoreau must have spent lots of his evenings and weekends writing what amounts to 2 million words in his journals!

For more details, the article is available at Elsevier:  http://www.sciencedirect.com/science/article/pii/S000632071300219X

The death of Walden's mayflower

Posted by Richard Primack

Richard examines a patch of trailing arbutus cascading down a forested slope in Concord. This site does not have public access.

The single trailing arbutus plant that grew for many years next to the trail around Walden Pond recently died. Trailing arbutus is known botanically as Epigaea repens, or more familiarly as mayflower, and is the Massachusetts state flower. It is recognized by fragrant pink flowers produced below ovate, evergreen leaves that sprawl across the ground. Henry David Thoreau referenced trailing arbutus many times in his journals during the 1850s, noting its spring flowering time.  He found it at about three localities in Concord. Later botanists have noted half a dozen additional Concord sites for this species. I have seen three small patches in Concord, with the Walden Pond plant being the only one that was readily accessible to the public.

I have shown this isolated plant to dozens of students and nature lovers during walks around the pond. Now the plant is dead and only dried brown leaves remain. Visitors to Walden Pond are no longer able to observe and enjoy this beautiful and iconic wildflower.

The dead trailing arbutus plant growing on the edge of the Walden Pond trail. 

The decline of trailing arbutus and other wildflowers in Concord demonstrates that simply protecting land is not enough to preserve the diversity of life. Sometimes we must take action to reduce these threats if we wish particular species to remain on the landscape. Such actions include removing deer and invasive species, maintaining open river meadows through mowing and tree cutting, and restoring lost species. Without such management actions, we will not experience the diversity of wildflowers, butterflies, birds, and other species that enriched the life of Thoreau and inspired his writing. While we have already lost the trailing arbutus at Walden Pond, its loss may serve as a call to action for the protection of nature.   

Banding birds at the Palomarin field station

Posted by Amanda Gallinat

With our research in phenology, we are currently most interested in the bookends of the growing and breeding seasons, spring and fall, here in Massachusetts. That leaves the summer which, with the exception of Caitlin working away in Acadia, is our time to catch up on writing, attend conferences, and spend time with our families. With parents and a partner out west, I spent the month of July working from sunny California!

 

Point Blue's Palomarin is located on the Point Reyes National Seashore

Okay, I actually spent the month in foggy Marin County, at Point Blue Conservation Science's Palomarin field station-- or as many call it, Palo. Palo, like Manomet in Massachusetts, is a long-term monitoring station on the coast; biologists have been banding birds at Palo year-round since 1966. In the breeding season, another group of Palo biologists maps nests and territories of breeding birds on the grounds, even banding nestlings for a long-term genealogical data set. Many of the biologists that do this work are interns, hired on for a season to learn current bird monitoring techniques. That was me, for most of 2011. I loved being an intern at Palo, and in addition to bird ID and bird monitoring, Palo taught me the value of observation and natural history knowledge in conducting good science.

 

Me holding a banded Townsend's Warbler, 2011

So I returned to Palo this July to live with friends, read and write about phenology, and to do some songbird banding! We opened our mist nets 15 minutes after sunrise and closed them 6 hours later, checking for birds every half hour in between. Palo has 14 net locations that range from coastal scrub habitat to douglas fir forest and now, at the tail end of the breeding season, we were catching lots of recently-hatched birds and adults that were finishing up breeding and just beginning to molt. We caught between 20 and 60 birds most days, primarily Swainson's Thrush, Wilson's Warblers, Song Sparrows, Wrentits, and Selasphorus Hummingbirds. It was great to be back.

 

Juvenile Wrentit, banded and returned to the nest as part of Palo's nest searching program

Stations like Palo and Manomet help us answer questions about phenology, like whether migratory songbirds are changing their arrival and departure dates over time in response to climate change. And that's the value of long-term monitoring stations-- they help us answer questions that, 40 years ago, we didn't know we would have today.

So, if you ever find yourself in Marin County, I strongly recommend a visit to the Palomarin field station!
(Photographs courtesy Sam Roberts)

Field Station Concordia

posted by Richard Primack

Our research on climate change, Thoreau and Concord has expanded over the past few years to include a wider range of people and field sites. With the Concord Museum and curator David Wood, we began to more explicitly connect history and climate change biology, resulting in the current exhibit. In another collaboration, we have been working with Jane Marsching, a professor at the Massachusetts College of Art and Design and a media artist, to connect themes of art and science. Together we launched a user-friendly version of NELOP, the New England Leaf Out Project, that requests people to contribute observation on the leaf out times of common tree species. 

Jane Marsching at her Field Station Concordia at the deCordova Sculpture Park and Museum

 

Jane has been developing these and related themes as her contribution to the new Work Out program at the deCordova Sculpture Park and Museum in Lincoln, MA.  She has built a half-scale, open version of Thoreau’s cabin as:   

“a platform for data collection, community gathering, citizen science, handmade and digital explorations of plant and animal life, and a conversation full of questions about the vibrancy of matter and our role in the stresses and resiliences of ecosystems.”

This platform provides many opportunities for interaction with the artist and with the natural world.

For more information, check out:

http://www.fieldstation.net/

Jane Marsching in her half-scale version of Thoreau's cabin

Talkin' Tambo

Post by Libby Ellwood

I've recently had the pleasure of visiting several Japanese rice paddy fields, known here as "tambo". Rice is a staple of the Asian diet and as such tambo play an integral part in the Japanese economy, culture, and ecology. As with many forms of modern agriculture around the world, there are different ways rice can be grown. Tambo dot the landscape of Japan, forming a matrix that demonstrates the differences in cultivation  - everything from traditional methods that often require a high level of manpower and minimal outside inputs, to high-tech methods that rely on automated machinery and a cocktail of fertilizers. The particular method of rice farming that a farmer chooses to employ has far-reaching effects from the quality of the rice itself, to the health of the ecosystem, and even to the impact of tambo on climate change. That's right - even rice cultivation can affect the climate and certain types can mitigate climate change.

The most modern rice growing methods are often devoid of living creatures. Due to ecologically harmful inputs of fertilizers and pesticides, concrete infrastructure that make it difficult for organisms to move between irrigation troughs and paddies, and heavy machinery that stirs up fragile soil layers, modern tambo are relatively sterile environments.

A middle ground of tambo is organic methods. Here, natural additives are used at various times during the growing season in order to boost production. Even these methods though can result in anoxic (no oxygen) conditions as increased decomposition robs the water of dissolved oxygen that frogs, fish, and microorganisms depend on.

However, in northern Japan it is possible to grow rice completely naturally. Tambo that utilize this method resemble the most diverse of wetlands. The water teems with daphnia and you can't take a step through the paddy without numerous frogs scurrying away. Some of the most fascinating animals can be found here, including water spiders, mole crickets, and giant water bugs. These paddies are often flooded in the winter, making them ideal grounds for geese and other waterfowl that have faced habitat destruction throughout their range. And, you guessed it, these natural tambo are the preferred method when it comes to climate change mitigation.  They have many of the same benefits as wetlands and can store substantial amounts of carbon and methane. By working within the bounds of the ecosystem, farmers can create resilient tambo that can weather droughts and floods, store greenhouse gases and serve as an important habitat for plants and animals.

While rice paddies are not a substitute for true wetlands, when managed well they can feed a growing human population and provide habitat and ecosystem services all while having a net positive effect on the environment. Still curious about rice paddies? Check out this tambo NGO (and use your browser to translate it!).

The last plant to leaf out at the Arnold Arboretum: Makino Rhododendron

Post by Richard Primack

Every spring for the past three years, we have been monitoring the leaf out times of over one thousand species of trees, shrubs, and vines at the Arnold Arboretum of Harvard University. We try to survey the entire collection at least once a week, recording when the first flush of new leaves are produced for each species.

The work is important for ecosystem research in determining when the growing season begins, when new leaves are available as food for animals, and when plants start to absorb atmospheric carbon dioxide. This work is also important in determining the ability of plants to respond to a warming climate. And lastly, the variation among species in leaf out is a rich area of natural history that has been surprisingly neglected.

At the Arnold Arboretum in 2013, the first plants began to leaf out in mid-March. These were mainly species of honeysuckles (Lonicera), gooseberries (Ribes), and privets (Ligustrum). The last species did not leaf out until 2 to 3 months later, and these were mostly species of pine (Pinus), fir (Abies), and spruce (Picea), along with a few evergreen rhododendrons. The last species to leaf out at the Arnold Arboretum in 2013 was the Makino Rhododendron (R. makinoi), which did not produce its new flush of leaves until mid-June, three months after the first species.

Rhododendron makinoi, the last plant species to leaf out at the Arnold Arboretum. 

(This photo was taken in mid June of 2013) 

We are currently cooperating with botanical gardens from around the world to monitor leaf out times on a larger scale. Our goal is to determine the relative advantages and disadvantages of early and late leaf out times.

For further reading, see http://arnoldia.arboretum.harvard.edu/pdf/articles/1976.pdf