(HOST) On a recent vacation, commentator Ted Levin was running along the Hudson River when he noticed several branches of ornamental cherries in bloom. That got him thinking about the changing climate and how it may affect Vermont’s native plants and animals.
(LEVIN) Contrary to the title of Bill McKibben’s book, “The End of Nature,” which brought global warming to the forefront, nature does not end. It never ends, only changes – and always has since the first bacteria rose out of the primeval ooze, nearly two billion years ago. Natural selection, the unifying force of evolution, translates the environment into organism design.
Climate change will be a factor in the success and failure of Vermont’s native species. A crude generalization would be: plants and animals at the southern end of their ranges – those species whose center of distribution is north of Vermont – will be stressed. In this category would be the alpine vegetation on the summit of Mt. Mansfield and Camel’s Hump, whose range has been shrinking ever since the last glaciers melted 11,000 years ago.
Year-round boreal birds – gray jay, spruce grouse, American three-toed woodpecker, black-backed woodpecker – residents of spruce swamps in the Northeast Kingdom might disappear as more competitive southerly species – ruffed grouse, hairy woodpecker, downy woodpecker – expand their range into terrain no longer as cold and as forbidding. I believe that Bicknell’s thrush might also find itself in jeopardy. Recently split from the more ubiquitous gray-cheeked thrush and declared a separate species, Bicknell’s thrush has a patchy distribution in the higher elevation spruce forests of the Northeast, including the Green Mountains.
Four to six thousand years ago, Earth entered what climatologists called a climatic optimum or the hypsithermal interval. Back then Vermont’s weather was like modern-day Virginia. During the hypsithermal, southern plants and animals moved north and colonized new terrain. Today, these species are found in micro-habitats scattered throughout the state: tupelo trees in Vernon; rattlesnakes, five-lined skinks, and rat snakes on west-facing ledges near Lake Champlain; white oak, black birch, sycamore, and bitternut hickory in the Connecticut River Valley; black oak, sassafras, tulip poplar, and redbud in southwestern Vermont; orchids and insectivorous plants in bogs and fens and forests. Will their ranges all expand?
Opossums might be favored by a less severe winter; their ears and tails no longer frost-bitten by the cold. Global warming has been around for at least fifty years, and during the past thirty years blue-gray gnatcatchers, Carolina wrens, red-bellied woodpeckers, and turkey vultures expanded their range into Vermont. Not far behind them are Chuck-wills-widows, black vultures, great egrets, Acadian flycatchers, white-eyed vireos, and worm-eating warblers.
If current weather patterns continue, seeds and sprouts better suited to short winters and hot summers would be favored. I imagine sugar maples will survive, though they might yield less sap. After all, their range already reaches into northern Florida.
Global warming – as an agent of natural selection – will affect many species, and the effect will be echoed in changes in their distribution and abundance. Some will arrive. Some will survive. And others will disappear.
Ted Levin is a writer and photographer and winner of the 2004 Burroughs Medal for Nature Writing.