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Tracking Climate Change in Backyards Everywhere

by Mary Jasch

Alyssa Rosemartin, Application Specialist, of the USA National Phenology Network, studies climate change by collecting and analyzing the timing of life cycle events of plants and animals every year.

The National Phenology Network (NPN), based at the School of Natural Resources and the Environment, University of Arizona, has been tracking 700 to 800 plants species and 400 species of mammals, birds, reptiles and fish to understand the effects of climate change on plants and animals since they started in 2009.

“We are a research organization that collects data on how climate impacts change and timing,” says Rosemartin of the 27 scientific papers and 9 million-plus phenology records NPN has written and compiled.

Coming from the Greek pheno (show or appear), “phenology” is the study of the timing of life cycle events of plants and animals, i.e. when things appear; not to be confused with “phenotype,” how things look differently.

Any individual or group who wants to witness climate change in their own backyard can be a “backyard scientist” by contributing data to NPN and using the tools provided on the NPN website. Currently, the USA National Phenology Network has 8,500 active observers; 3,000 are individuals. Others are groups, such as “Tree Spotters” at Harvard’s Arnold Arboretum, where Rosemartin conducts classes for citizen scientists.

Observers record the dates of plant events including leaf buds and leafing out, flower buds and full flowering, leaf color and leaf drop, immature and ripe fruit as well as lack of fruit. They follow fish, bird and mammal migrations, nest building, butterfly emergence and other events in the lives of animals.

“The importance of backyard observers can’t be stressed enough,” Rosemartin says. “None of what we’re doing would be possible without people in their backyards looking at plants and animals.”

Take the Lilac Data Collection that began in 1956 by University of Montana meteorologist, Joe Caprio. He wanted to get better temperature data across the West, but people in backyards didn’t have thermometers and there was no money to buy them. He reasoned that if lilacs responded to temperature, they could be used as biological thermometers, so people bought lilacs to plant in their yards and recorded dates of budding, flowering and leaf drop. At the same time, Caprio gathered temperature data for those dates from other nearby sources. The combined data sets became known as the Lilac Data Collection. Those early lilac observers never thought their data would be used today to predict climate change or to determine an early or late spring.

These days, 10% of volunteer backyard observers have thermometers and rain gauges. For the rest, temperature and rainfall is collected from the National Oceanic and Atmospheric Association, the National Weather Service or the nearest weather stations.

“We don’t know what the climate drivers are but we know what climate is doing to plants and animals,” Rosemartin explains. For instance, NPN combines the data to learn how many Growing Degree Days are needed to affect plant growth.

What is a Growing Degree Day (GDD)? Today, GDD is the most common index used – a measurement of heat – needed for a plant to accomplish certain life events such as fruiting. For instance, corn has a “base temperature” of 50° F because it will grow very little at temperatures below that. If it is 56° degrees, that equals 6 GDDs. If the next day is 57°, that is 7 additional. The GDDs accumulate until they add up to 800-1400 GDDs when corn has been shown to reach maturity. The lilac, Syrinia vulgaris, begins flowering at 80-110 GDD.

Another way of understanding: If you plant a tomato in Boston, Massachusetts, and one in Toms River, New Jersey, on the same day, the tomato in NJ will ripen faster than the tomato in MA with earlier warmth and more Growing Degree Days.

NPN has found patterns in the long-term Lilac Data Collection:
• Spring comes earlier
• lilac leaf-out and bloom has been, on average, one day earlier per decade across the country. Locations vary, though, due to other factors.

“They have collected a lot of lilac data over time to create a predictive model of climate warming, and have created a six-day lilac forecast data – how do current conditions compare to long term,” says Rosemartin.

But what about rain or lack of it, sunny or cloudy days, hydrology, wind speed and soil conditions? They all, too, affect flowering and fruit and trickle down to how much food has been produced and consumed by insects and how that affects larval stages and pollination, fertilization and even nest building and migration.

“We start with temperature but know we’re missing a big part of the picture,” Rosemartin admits. “The signs of the seasons are all around us, but when you start collecting data and looking more closely you realize we still don’t understand a lot – why things are happening, how to predict. We don’t have the ‘why.’ We have the ‘what’ and try to figure out the why.”

Plus, NPN discovered that Spring 2012 was the earliest ever recorded nationwide. Then, a couple years later, the East Coast experienced a frozen, snow-covered winter, followed by one just warm enough for frequent frozen rain. “Climate change is not happening steadily. The change is variable over time,” she says.

NPN moves its research on climate change impacts on plants and animals forward to academic researchers, decision makers in cities, national parks and government organizations.

“We tell our lawmakers in Congress and other organizations like the EPA and DOI how climate is impacting the nation as a whole. It informs the information they have. For example, how climate change is advancing Spring Onset so national parks are thinking about timing their operations. One example: At Acadia National Park, college kids used to volunteer to remove invasive species after school let out. Now spring arrives before school lets out so the park budgets money to hire people.

The bottom line that the data is showing:
looking back, spring has come earlier one day per decade.
Looking forward, spring is arriving two to four days earlier per decade.
• The rate of change is increasing.
• The trends will pick up in the coming century so that by 2100, spring will arrive three weeks earlier.

So should gardeners start planting more Southern species of woody plants and perennials? Rosemartin says yes – but plant species that can handle a wider and variable temperature range.

A Few Tidbits
• Brandt geese no longer all migrate out of Alaska news story
• Spring 2012 was the earliest on record, Washington Post article,
• Maple syrup in Ohio, 2016, the earliest in 30 years, occurred the last week of January
• NPN written vignettes that translate recent interesting research
• First leaf for lilacs and honeysuckles is advancing a day per decade ranging from 0.8-1.6 days. First bloom is getting earlier 0.4 - 1.2 days.

USA National Phenology Network:
National Climate Assessment's Northeast Region:
Nature’s Notebook:
Spring Index Forecast Maps: /data/phenology_maps][/url]
NJ DEP has a summary report.
Spring Index link to the graph and explanation.

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published January 25, 2017

Photos to enlarge

Backyard scientist, Sara Schaffer photo

Alyssa Rosemartin, climate change tracker and applications specialist. Photo courtesy National Phenology Network

Using Nature's Notebook, Brian Powell photo

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