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A Talk on the Wild Side.

Massachusetts: Changes at Walden Pond

A meadow with yellow flowers

Adaptation iconLocation: Concord, Massachusetts
Size: over 3,800 acres
Open to the public: Yes 
Related Websites:
U.S.A. National Phenology Network

Great Meadows National Wildlife Refuge
USA National Phenology Network           
Project BudBurst
Climate Change Threat: Warming temperatures, invasive species
Contacts: Terri Edwards, USFWS Public Affairs, (413) 253-8324 

Photo at left: A field of native flowers, Rappahannock River Valley National Wildlife Refuge, Virginia. Credit: USFWS.

Massachusetts: Changes at Walden Pond

by Frank Wolff

“It is astonishing how soon and unexpectedly flowers appear, when the fields are scarcely tinged with green. Yesterday, for instance, you observed only the radical leaves of some plants; to-day you pluck a flower.”  -- Henry David Thoreau

Great Meadows National Wildlife Refuge is located in Concord, Massachusetts. The area was home to a dedicated naturalist in the mid-1800s. He built himself a house on 14 acres of woods on the bank of Walden Pond. He dutifully and diligently recorded the flowering times of hundreds of plants as well as the behavior of rabbits, red squirrels, mice, birds and other animals for six years.

A photo of Henry David Thoreau

Henry David Thoreau, 1856

Credit: Photo courtesy of The Thoreau Society Collection at the Thoreau Institute at Walden Woods

His name was Henry David Thoreau.

Thoreau provided an extensive array of data that has proven invaluable as a baseline for phenological research that continues today. Phenology is the study of events in nature that are influenced by climate and seasonal change.

A study conducted by Abraham J. Miller-Rushing and Richard B. Primack found that climate change is causing many plants to flower much earlier today than they did in the past. The two researchers used Thoreau’s observations, as well as the work of Alfred Hosmer, another naturalist who studied the ecosystem around Concord, as a comparison to their own modern-day observations. Their research concludes that in Concord, plants are now flowering seven days earlier on average than they did in Thoreau’s time.

But not all plants are equally impacted by climate changes. Some species have the ability to track seasonal temperature change and will flower earlier when temperatures are warmer. Other species don’t track temperatures as well, and will continue to flower at the same time every year—regardless of temperature variations. The ones that don’t track temperatures as well are more likely to suffer a decline in numbers; they also tend to be related to one another, so entire plant families are impacted.

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A field of purple clover
Field of red clover, Silvio O, Conte National Fish and Wildlife Refuge, Massachusetts. Credit: Maddie List/USFWS photo on http://www.flickr.com/photos/usfwsnortheast

Unfortunately, research also suggests that non-native species may be the ones that adapt the best to climate changes. A study conducted in Thoreau’s woods shows that non-native plant species are far better able to respond to recent climate change by adjusting their flowering time. The researchers discovered that mayweed chamomile (Anthemis cotula L.), which is native to the Mediterranean, shifted its flowering time over the years and now blooms 23 days earlier than it did in 1900.

The impact of thriving non-native species can be devastating to the environment. Non-native plants that propagate and become invasive can have tremendous negative impacts—both ecologically and economically.  An estimated 5,000 alien plants exist in the United States, displacing native species. One example is the European purple loosestrife. It has been spreading at a rate of 115,000 ha/year and has been blamed for reducing the biomass of 44 native plants and endangered wildlife, including bog turtles and several species of ducks that depend on the native plants. Loosestrife now occurs in 48 states and costs $45 million per year in control costs and forage losses.


New England aster, Great Bay National Wildlife Refuge, New Hampshire. Credit: Greg Thompson/USFWS photo at http://www.flickr.com/photos/usfwsnortheast

As climate change affects plants, it also affects the rest of the ecosystem, including:

  • Food sources
  • Emergence of insects
  • Pollination
  • Bird migration

In nature, timing is everything. It can influence recreation, agriculture—even economics. Whether people come to see the fall colors, watch migrating whales or catch a glimpse of rare birds, visitors to the Northeast impact the economy to the tune of millions of dollars. As the timing of nature’s events change, so will the timing of the tourist seasons.

“It matters if a plant changes flowering by even one day,” said Miller-Rushing, one of the country’s top phenology researchers, now with the National Park Service. “How it changes is relative to what it is dependent on. If pollinators are late or water isn’t available, that has a real impact. Small changes can fundamentally change an ecosystem.” 

A little girl looks at a pink flower

A “budding” scientist examines a blooming azalea in her front yard

Credit: Photo courtesy of Frank Wolff

Citizen Scientists

There is an ongoing effort to share phenological data from around the world through the USA National Phenology Network. The group has partnered with the U.S. Fish and Wildlife Service, The Wildlife Society and the U.S. Geological Survey to create a program that anyone from an amateur in their own backyard to a skilled scientist in the wild can collect data that can be shared, integrated and compared to data sets over time.

In addition, the U.S. Fish and Wildlife Service is a sponsor of Project BudBurst—a network of volunteers who collect data on the timing of leafing, flowering and fruiting of plants. The data they collect is shared with scientists across the country in an effort to learn more about how different species of plants respond climate changes.

It’s a great way for school groups, scout troops, backyard naturalists, ecologists, nature-lovers and others to provide valuable scientific data—even in their own backyard.

All the tools and information are available on the Project BudBurst website. 

Well, good thing people discovered Global warming a decade before the 1900 start date of the changes at Walden Pond. AND they had a more scientific approach to the realities of Global warming than Politicians do today....
# Posted By Paul | 4/25/11 11:33 AM

It seems odd that non-native plants are better at adjusting to a change in climate than native species. Will North American native plants that are in Europe outcompete Europe's native plants?
# Posted By Craig | 4/25/11 11:40 AM

Good question, Craig. We didn't research data from outside the U.S. for this story. I will ask our subject matter experts for additional information.
# Posted By Terri Edwards, USFWS | 4/25/11 2:10 PM

Great information! The damages caused by invasive species and the exacerbating link to climate is one of the things that most folks don't appreciate. I hope you'll have another demonstrating the linkages between climate, wildlife populations, and the many diseases vectored by biting insects!
# Posted By Tim | 4/25/11 8:50 PM

The U.S. Global Change Research Program is a good source of information on these and other regional impacts. http://tinyurl.com/3aw5lle
# Posted By Dave Eisenhauer, USFWS | 4/26/11 2:22 PM

I would think that invasive species are "invasive" because of their adaptability to a variety of climatic and soil conditions. Some of our natives likely behave as "invasives", as well - not in the sense that they are non-native, but in the manner that they colonize/spread/out-compete other less adaptable speices.
# Posted By Rob | 4/26/11 4:41 PM

Hey, Tim, thanks for the comment. While we don't yet have a story that specifically deals with the linkage you mention (re: climate, wildlife and disease), the Intergovernmental Panel on Climate Change provides some good information on the subject: http://www.ipcc.ch/ipccreports/sres/regional/index... This is a great topic for a future story.
# Posted By Dave Eisenhauer, USFWS | 5/2/11 4:15 PM

Reducing trees plants are main reason for global warming. These days every one should plant a tree on any special day. We have to take this initiative.

# Posted By Pulkit | 8/11/11 11:09 PM

I would like to go about this information deeply. Thanks for your resource, i will refer this article.
# Posted By Bangalore Flowers | 8/15/11 8:20 AM

Concerning Monarch butterflies (as I see one in the pic), their population is decreasing: http://whatdocaterpillarseat.com/what-do-monarch-c... , so looks like plant invasion is one of the reasons which causes shortage of host plants. I try to create best conditions for these creatures in my garden, but it's a drop in the ocean. With them, a problem is that a single reservation is not enough - they migrate.
# Posted By Martha | 1/23/12 8:40 AM

It seems unusual that non-native plant existence is more preferable at modifying with a customization of environment than native species. Will U . s . states . States local plants that are in The european union outcompete Europe's native flowers?

# Posted By | 8/30/12 5:17 AM

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# Posted By cristina | 2/19/16 12:03 AM

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# Posted By Muhaiminul Haque tushar | 1/29/17 4:47 AM
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