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Warming Worries

n the ecological symphonies now playing out in the wetlands and woodlands, fields and forests of our Chautauqua watershed and elsewhere, questions remain about the long-term impacts of our warming world on the intricate synchrony of Life’s dance. Photo by Becky Nystrom

Evidence of climate change is all around us. The lack of snow and increasingly wetter, warmer winters here in the Chautauqua region are troubling warning signs. I worry about the trees and the creatures dependent upon them, and about our seasonal economies based on recreation, tourism, farming, and forestry. Our maples, beech, birch, apple, cherry, dogwood, and other native woody plants are superbly adapted for the challenges of wintertime, but they require prolonged episodes of frigid temperatures for critical metabolic changes.

In the longer view of climate change, as substantially warmer winters become the norm, it’s possible that our grandchildren may witness the tragic decline of some of our most beloved native trees and shrubs here in Western New York. For without sufficient periods of exposure to the icy chill, spring buds of northern trees can’t break out or develop into flower blossoms or leaves, nor can most tree seeds germinate when warmer days arrive. Without flowers, there can be no fruits, nor the seeds they contain. And without seeds, there is no reproductive future for that species in that place. The cold is critical.

Evidence suggests that global warming is already having pervasive effects on a host of plant and animal behaviors and interactions and posing potentially dire threats and disruptions to ecosystems, biodiversity, and the ecosystem services on which people depend. According to the just-released Fourth National Climate Assessment, U.S. Global Change Research Program, 2018 report https://nca2018.globalchange.gov, as well as abundant data from the USA National Phenology Network https://www.usanpn.org/usa-national-phenology-network, studies have revealed a “globally coherent fingerprint of climate change impacts” on the rhythms and relationships of the natural world. Phenology explores the seasonal tempo of nature’s calendar, such as the timing of autumnal colors, seed set, hibernation, springtime bud-burst, leaf-out, flower blooming, insect emergence, pollination, songbird and butterfly migrations, courtship and mating, nesting, egg-hatch, and much more. In turn, such pulses and patterns affect everything else – oxygen production, carbon cycling, food webs and energy flow, community composition, and species diversity and survival…or not.

In the context of accelerating climate change, numerous studies are raising alarms concerning possible de-coupling of key interactions within a given community as organisms differentially respond to milder winters, earlier spring warmth, and longer growing seasons but become “out-of-sync” with partner species upon which they depend. While phenology allows humans to gauge the pulse of an ecological community, its revelations of mismatch in timing between species portend significant and sobering impacts on vital relationships such as plant-herbivore, plant-pollinator, predator-prey interactions, and non-native species invasions. For example:

¯ Plant-pollinator relationships are disrupted when changes in spring blossoming, nectar release, and pollen production no longer sync with the emergence of honeybees, bumbles, and other pollinating insects or the arrival of spring migrants such as hummingbirds and monarch butterflies. Native bees have emerged an average of 10 days earlier over the last 130 years, with an acceleration of this trend in the last 40 years, while some flowers are blooming earlier as well but others are not;

¯ Changes in the timing of bird migrations have been documented throughout the United States. Some migratory birds now arrive too late for the peak of food resources at their spring breeding grounds because temperatures at wintering grounds are changing more slowly than those in the north. Dr. Peter Marra and colleagues of the Smithsonian Environmental Research Center analyzed 40 years of data for 15 neo-tropical songbirds arriving in Pennsylvania and Ontario, Canada, including warblers, wood thrush, and tree swallows, and found that for every 1.8 degree Fahrenheit increase in springtime temps at the northern sites, migrants arrived one day earlier, while the plants in these breeding habitats budded three days earlier. In turn, insect prey dependent upon those host plants emerged earlier as well, leaving a reduced food supply for parent birds to feed their nestlings.

¯ Long-term observations of the flowering of lilac, honeysuckle, cherry, apple, and other species indicate that the onset of spring has advanced 1.2 to 1.6 days earlier per decade across the northern hemisphere in response to increased winter and spring temperatures, with earlier leaf and bloom events occurring 4 to 8 days sooner than in decades past. Longer growing seasons may be favorable for many plants but mismatch with the timing of their pollinators and seed dispersers may not.

¯ Future springs in the U.S. are expected to arrive three weeks earlier by the end of this century, with widespread and uncertain consequences. Increased pests and invasive species outbreaks, both aquatic and terrestrial, are also expected.

Climate change is complex, and nature is resilient – but timing is everything, and relationships take time. In the ecological symphonies now playing out in the wetlands and woodlands, fields and forests of our Chautauqua watershed and elsewhere, questions remain about the long-term impacts of our warming world on the intricate synchrony and music of Life’s dance.

As climate change accelerates, the ancient rhythms of relationship will be altered, and the harmony of the symphony may well yield to the discord of humanity’s ways.

The Chautauqua Watershed Conservancy is a local not-for-profit organization dedicated to preserving and enhancing the water quality, scenic beauty and ecological health of the lakes, streams, wetlands and watersheds of the Chautauqua region. For more information, call 716-664-2166 or visit www.chautauquawatershed.org or www.facebook.com/chautauquawatershed.

Becky Nystrom is a Professor of Biology at Jamestown Community College, a founding trustee and former board director of the CWC, and a longtime CWC supporter and volunteer.

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