The Register-Herald, Beckley, West Virginia

January 12, 2014

The bright side of frigid temperatures

Chill could kill insects that harm hemlock, ash

By Clint Ferguson
For The Register-Herald

— There aren’t many times when you see the thermometer drop below zero around here, but this past week it was 9 below when I woke up. The weather man said the wind chill was 25 below. Frigid, frozen, blustery, no matter how you describe it, it was bone-chilling cold out there.

I often think about the wildlife when it gets this cold. It’s amazing how they can adapt and survive. Deer like to find a pine or hemlock stand and lie low there as it creates a thermal refuge. The dense evergreen trees provide a wind block and the temperatures can be warmer underneath them.    

Deer conserve energy by not moving much and relying on their fat reserves to make it through winter. In poor mast years, like this past one, some of the weak and malnourished deer will be lucky to make it to the spring green-up. Luckily we haven’t had any deep snows yet, but it’s only the beginning of January, and there’s a lot of winter left.    

These freezing temperatures could actually help some of the trees in the woods. Hemlock and ash trees are two that could actually benefit from these below zero temperatures. Both tree species are currently being attacked by invasive insect species.    

The hemlock woolly adelgid (HWA) was first detected in West Virginia in 1992 in the eastern panhandle. Since then it’s spread and infested 46 of the 55 counties in the state. In 2003, mortality from the pest was documented, and several hemlock trees have succumbed to the wrath of the hemlock woolly adelgid since then.    

It has been found that in freezing cold temperatures and ice storms in particular, the HWA populations tend to fall and get knocked back so to speak.  The cold won’t completely eliminate the pest, but it can help reduce how heavily infested a tree will be. Right now, the future outlook for our hemlock trees isn’t looking good.    

Ecology wise, the loss of hemlocks in our forest could affect other shade tolerant plant species as well as our trout streams. Without the shade, water temperatures will warm up and the cold-tolerant trout won’t survive. Also, thermal refuges for deer and other wildlife will disappear.

Grouse rely heavily on the cover of hemlocks in the winter to protect them from predatory birds circling overhead. The hemlock tree plays an important role in the forest but unfortunately seems to be on the losing end of the battle.    

Emerald ash borer (EAB) is another invasive insect species that has found its way to West Virginia. It was first detected in 2007 in Fayette County and was believed to have been brought in from infested firewood. Since then, the West Virginia Department of Agriculture has launched its don’t move firewood campaign.    

The WVDA encourages folks to not move firewood for long distances, especially when going camping. That’s one of the ways the invasive insect can be transported from one place to another. It’s better to collect and burn all firewood from the camping area than to bring your own.

Currently 27 counties are infested with EAB, and that number continues to grow every year. I recently read an article from Minnesota, which also has EAB, and the forester interviewed felt confident that this freeze will help combat the invasive there. EAB overwinter as larvae underneath the bark and if become frozen, they’ll die.    

It all depends on how cold it gets and stays to completely freeze them since they are protected underneath the bark. This critter has spread quickly and fast here in W.Va., and mortality is starting to show. EAB has caused devastation to the ash trees in the upper Midwest and will more than likely do the same here.  Hopefully this cold snap will help the ash trees out.

The temperatures have warmed since then and we thawed out for the weekend. Looking on the bright side, we more than likely experienced the coldest temperatures of the year already. And it might have helped a few trees as well.