January 30th, 2013 by Joshua S Hill
New research on trees in the continental United States has found that new spring leaves might start to bud up to 17 days earlier in the coming century then they did prior to the current anthropogenic climate change.
The research is behind a new study by Princeton University researchers who used a new model that relied on warming temperatures and the ever increasing lack of cold days to predict when spring budburst would take place.
Led by David Medvigy, assistant professor in Princeton’s department of geosciences, the new model was published last year in the Journal of Geophysical Research. The new study, published online in the journal Geophysical Research Letters, saw Medvigy and his colleagues test the new model against a broader set of observations collected by the USA National Phenology Network, “a nation-wide tree ecology monitoring network consisting of federal agencies, educational institutions and citizen scientists.”
By the end of this century, the team estimate that red maple budburst will occur 8 to 40 days earlier than the late 20th century average, depending on which part of the country the trees are located: northern parts of the US will have more pronounced changes than southern parts of the country, with the largest changes occurring in Maine, New York, Michigan, and Wisconsin.
This news comes hot on the heels of research which looked at the phenology records of Henry David Thoreau and Aldo Leopold. The researchers found that, based on the records taken by Thoreau and Leopold, flowers are blooming earlier and earlier each year.
Compared to the timing of spring flowering in Thoreau’s day, native plants such as serviceberry and nodding trillium are blooming 11 days earlier, on average, in the area around Concord, Mass., where Thoreau famously lived and worked. Nearly a thousand miles away in Wisconsin, where Leopold gathered his records of blooming plants like wild geranium and marsh marigold, the change is even more striking. In 2012, the warmest spring on record for Wisconsin, plants bloomed on average nearly a month earlier than they did just 67 years earlier when Leopold made his last entry.
The red mapble is not the only tree budding earlier, either. Medvigy and his colleagues looked at other species of trees, and found that budburst shifted to earlier in the year in both early-budding trees and late-budding trees (though the effect was more pronounced in late-budding trees).
The finding is also interesting from the standpoint of future changes in springtime weather, said Medvigy, because budburst causes an abrupt change in how quickly energy, water and pollutants are exchanged between the land and the atmosphere. Once the leaves come out, energy from the sun is increasingly used to evaporate water from the leaves rather than to heat up the surface. This can lead to changes in daily temperature ranges, surface humidity, streamflow, and even nutrient loss from ecosystems, according to Medvigy.
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