New England forests may seem immune to the consequences of climate change. Hurricanes are infrequent, and there is no risk of ocean flooding or raging wildfires. In an age of wild weather, New England forests seem remarkably stable. If only that were true. Climate change is actually reshaping this ecosystem inconspicuously. The warming climate and its related impacts are causing more changes to the ecosystem than New England forests have ever faced.
How will the climate change in New England?
New England is already getting warmer and wetter. Climate is defined as the combination of temperature and precipitation in an area over a long period of time, and New England will continue to see changes in both. The region has already seen a 2.4°F increase in average temperature over the last century. Additionally, climate models predict that the speed of this warming is only going to increase. Temperatures are increasing particularly fast during the winter months, likely tied to the dramatic warming in the Arctic.
On the whole, precipitation is projected to increase across the year. The distribution of precipitation will likely also change. New England is projected to have both drier summers and wetter autumns and winters. Perhaps the most concerning disturbance is that the New England climate is predicted to become more unpredictable.
Just how unpredictable are we talking?
The popular term “weather whiplash” was coined to refer to the increasingly erratic weather patterns expected with climate change. It is a real concern in New England forests. In meteorological terms, it is often defined as rapid shifts between wet and dry or warm and cold conditions. For New England forests, this is particularly damaging in the case of “false” springs. Early warm weather can cause plants to begin budding prematurely, only to die when freezing temperatures return. Although this will not kill mature trees, it does wear them down, as they then must produce buds again or simply not have leaves that year.
Damage from a windstorm at Hubbard Brook Experimental Forest in New Hampshire.
How will climate change impact extreme weather events?
Short answer: There will be more. Whether caused by icy winter storms or violent summer thunderstorms, the consequence of increasingly unpredictable weather is more downed trees and broken branches.
As the weather intensifies, the potential for strong winds will create many more canopy gaps, or openings in the treetops, that fundamentally transform these forests. More light and precipitation reaching the forest floor gives saplings an advantage. Canopy gaps are the primary change agent in New England forests as these openings allow new species or age groups of trees to enter the forest.
How is climate changing invasive species in New England forests?
In recent years we have seen an increase in the diversity and abundance of invasive species in New England. Emerald ash borer, hemlock woolly adelgid, and gypsy moths are just a few of the invasive species currently munching through these forests. The changing climatic conditions, particularly the loss of cold winters that typically kill off pests, are making their movements easier. Trees that are already stressed by false springs, drought, and the changing climate are more vulnerable to an invasive pest. Research shows that entire tree species, like hemlocks and ash, are likely to be wiped out in the coming decades.
This loss of species will change New England forests and have staggering economic consequences. Although the total economic impacts of invasive pests can be difficult to quantify, one study estimates that the United States loses roughly $77 billion a year just to invasive insects. Stopping invasive species entirely is nearly an impossible task, but policies such as bans on moving firewood across state lines can help to slow the spread. Educating the public on signs and symptoms of invasive species to look for in their local trees may be our best hope of tracking the spread.
Forest devastated by hemlock woolly adelgid infestation in Pennsylvania.
What are climate migrant species and what do they mean for New England forests?
Climate migrants are defined as species entering a new ecosystem as a result of changing climatic conditions. They differ from invasive species in that they are not introduced through human behavior and they are native to a nearby geographic area. An example is red oak’s northward movement through New England forests. While invasive species tend to spread entirely unchecked, climate migrants usually just have a slight advantage over native species in an ecosystem. However, several climate migrants arriving all at once could destabilize these forests.
Why does it matter?
It is the compounding of these climate change impacts that poses the greatest danger for New England forests. Small canopy gaps created by natural disturbances such as the death of older trees, weather events, and pests are actually necessary for northern temperate forests. Some disturbance is essential to every ecosystem. But by drastically increasing the number of canopy gaps in the northeast, climate change is tearing apart the fabric of New England forests. No ecosystem was built to handle so much change all at once. Climate change poses a dire threat to New England forests. It’s time we noticed.
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