Over the years, our climate has steadily warmed.
In fact, since 1900 the average surface temperature of the earth has increased a little more than 2 degrees Fahrenheit. But most of the dramatic weather and climate changes have really happened since 1980. We’re referring to things like drought and flooding.
How are forests affected by climate change? Trees, similar to people, get comfortable in a specific place with certain growing conditions. When the climate changes so quickly, they don’t have time to adapt. This stresses them out and can lead to some issues that require extra care and attention.
This very topic was discussed in-depth on a Talking Trees podcast episode where Dan Herms, vice president of research and development for The Davey Tree Expert Co. shared his unique insights and experience with climate change and its impact on trees.
Let’s learn more about the effects of climate change on tree species so you can gain better insight into how your trees are coping.
What are the effects of climate change on trees? It has actually impacted trees quite a bit. A mega drought in the West has led to massive tree mortality and bark beetle outbreaks, while increased precipitation in the Northeast has raised forest productivity and tree growth.
Different tree species are handling this in different ways.
The “winning” trees have adapted to the warmer temperatures and wetter conditions and are experiencing increased growth.
But the “losing” trees have a different story that is very specific to each species, especially those located in the southern limit of their hardiness zones. For instance, birch trees in Michigan are not heat or drought tolerant, so they are suffering as they experience more of these conditions. And white pine trees in New England can’t handle the increased disease pressure as a result of higher precipitation and humidity. And tree species in the West are experiencing challenging conditions as a result of wildfires.
Climate change has certainly amplified tree disease and tree pest outbreaks.
Some tree insects are migrating north into areas where they didn’t survive well before because the winters were too cold. For instance, the southern pine beetle, which is native to the Southeast U.S. has migrated north into areas it's never been. The pest is killed by temperatures that drop down to 0 degrees Fahrenheit, and it’s no longer getting that cold in these states.
Another effect of climate change on tree species we’re seeing is some insects are now having multiple generations in one growing season since the growing seasons are lasting longer than they used to. For instance, oystershell scale, a serious pest of treeswent from having only one generation annually to two in northern Ohio and southern Michigan, resulting in higher populations.
There is some good news concerning climate change.
While climate change affects tree growth, there are also impacts of trees on climate change. For instance, trees provide shade, reducing electricity consumption and air conditioning costs. Trees also reduce stormwater runoff, which is even more necessary as precipitation and heavy rains escalate. Additionally, trees sequester and store carbon.
Planting trees can continue to help tomorrow’s climate. As you plant, you want to think about the future of the changing planting zones in your area. In 30 to 50 years, Ohio, for instance, which is in Zone 5-6, is predicted to become a zone 7 state as the weather continues warming. (Insert USDA Hardiness Zone Map here)Some trees like sugar maple and spruce will no longer do well there. But river birch, which is native in southern Ohio and farther south, as well as bald cypress – another southern tree, already do well in northern Ohio and even farther north and will continue to do so for many years to come.