How climate change affects trees around Centre County
Ticks, trees and trout — these are some of the things we can see changing right now in Centre County due to the first effects of climate change. But there are others: shifting growing seasons, bird migrations and sudden heavy rainfalls. Talk to anyone over 60, and they’ll tell you that things are changing.
Of course, not all these changes can be confidently attributed to our warming world. Nature is complex, and lots of factors affect both our weather and our environment. So when we talk about climate change, we are looking at long-term shifts in big, global patterns.
To be honest, I didn’t really understand this until Ray Najjar, a scientist friend of mine, explained the difference like this: waves are like the weather, the tide is like the climate. Waves go in and out, some big, some small — they change a lot. When the tide is going out, there are still some big waves coming in, but over time the edge of the wave arrives lower and lower on the beach.
We still get cold weather in Pennsylvania, but over time, those cold days are becoming less common. You can’t see this day-to-day, but you can observe the longer growing seasons that allow local farmers to pull in three harvests of alfalfa. That’s a benefit, but our warmer winters also have a downside.
My wife and I love to hike in Rothrock State Forest with our dog, and in the summer we probably spend five to six hours a week in the woods. We feel blessed to live in a place of such natural beauty, and checking for ticks is just part of the routine.
Like a lot of dog owners, we give our dog a pill to protect against Lyme disease. Ten years ago, our vet told us that we could skip the pill during the winter months, because ticks are dormant then. But recently we’ve seen ticks all year long, so the dog gets the pill throughout the year.
Ticks aren’t the only critters that like a warmer world — so does the wooly adelgid. In the most recent Pennsylvania Climate Impacts Assessment Update (2015), the authors write: “The northern limit of the hemlock woolly adelgid is currently believed to be determined by minimum winter temperatures, and it has been able to spread to the north and east in recent years due to warmer winters.”
This aphid-like insect doesn’t bother animals, it kills the Eastern hemlock, our state tree. Several years ago, I noticed a lot of these dead giants, along the Roaring Run at Shingletown Gap. What I didn’t know then is that these are some of the first victims of our changing climate.
Once I knew what to look for, I’ve seen this pest on hemlocks all over the forest. This year, however, I also noted its absence from Shingletown Gap, likely due to our seasonably cold winter. With climate change, those cold winters (like the ones I remember from my childhood) are becoming fewer and far between. And the wooly adelgid continues its advance.
Now, as any forester will tell you, the “charcoal flats” area of Rothrock is not a particularly healthy forest. Its trees were regularly harvested, its soil is badly eroded, and so there are lot of reasons these old hemlocks may have fallen. That’s why I’ve made it a mission to visit all 20 of Pennsylvania’s old growth forests.
A few weeks ago, we went to “Tall Timbers Natural Area” just over in the Bald Eagle Forest. Unfortunately, the ancient hemlocks here — just a little lower elevation and a little farther east — have already been devastated.
Hemlocks like to grow next to streams, and when they die, the streams get more sunshine and get warmer. Warmer streams mean fewer trout. It’s a vicious cycle.
So, it’s reasonable to ask, as Bob Smerbeck did in a letter to the editor in the Centre Daily Times a few weeks back, if there is “observed climate change in our area.” My answer would be: ticks, trees and trout.