Mar 31 2015
What happens when the interval between spring thaw and leaf out gets longer? Fifty years of detailed observations in New Hampshire’s Hubbard Brook Experimental Forest tell the tale.
In New Hampshire, where snow covers the ground all winter, spring thaw is a welcome event that finally exposes the soil. Weeks later after lots of warm air and sunshine the trees leaf out. In between these two events the sun warms the soil, the plants emerge, and wildflowers bloom.
Hubbard Brook Experimental Forest has kept detailed records of temperature, precipitation, snowpack, plants, animals, birds and invertebrates for more than half a century. An analysis of the data, published in BioScience in 2012, showed that the forest is getting warmer and wetter and the interval between spring thaw and leaf out has increased by 8 days. Climate change is separating spring’s above ground (air) responses from the soil responses.
In the post-thaw interval severe cold events freeze the exposed soil and kill plant buds and invertebrates. This threatens some deciduous trees (yellow birch and sugar maple in New Hampshire) and birds find fewer invertebrates when they return from migration. The record shows the mix of plants and animals is changing.
There are even changes in large animals. For the past 50 years the snowpack has declined, an outcome that favors deer over moose and that seems to be happening at Hubbard Brook.
More deer, less moose. If you write it down now you can see the trend later.
Read more here in Science Daily, December 2012.
(photo of moose by Ronald L. Bell, USFWS via Wikimedia Commons. Photo of deer by josephamaker2018 via Wikimedia Commons. Click these links to see the original images.)