My Turn: Posion ivy grabbing more and more territory in N.H.
The invasion is rapidly expanding. No, this isn’t the quadrennial influx of presidential candidates. It’s also not the intrusion of exotic insects that threaten to destroy our hemlock, ash and maple trees. And while ticks are also one of the pests that have dramatically increased in recent years, that’s not what I’m referring to. This new invasion started a while ago, mostly unnoticed, and only now appears to be increasing at an unprecedented rate.
For those of us who are allergic to this native plant, this invasion sends chills down our spines. Yes, we’re talking about poison ivy (Toxicodendron radicans).
Perhaps you’ve noticed it. In the past couple of years, poison ivy has been expanding its range and dramatically increasing its vigor and potency. I’ve noticed it, because I’m one of the 80 percent of Americans who are allergic to the urushiol oil that is contained in the tissues of poison ivy. It’s in the leaves, stems and roots and can be absorbed into human skin from even the slightest contact.
Unfortunately, I’m also one of those whose allergic reaction is severe, and I’ve had some pretty serious and unpleasant bouts, which have resulted in more than a few visits to doctors and occasionally the emergency room.
So, I notice when poison ivy is spreading. And lately it’s gone from being an occasional nuisance along the roads, disturbed areas and edges of fields, to an outright infestation. On my morning walk and drive to work, I now see it growing along miles and miles of roadside. It’s climbing up trees and buildings in places it never was before.
When I was as kid, my family spent three seasons in New Jersey and our summers in Gilmanton. I loved coming to New Hampshire, and realize now that one reason was that there was virtually no poison ivy to prevent me from thoroughly enjoying my regular explorations of the woods, fields and mountains here.
New Jersey, on the other hand, was a place where I had to exercise extreme caution before heading into the woods. It was in every vacant lot, in every un-mowed field. I learned early on: “Leaves of three, leave it be.”
One summer during my college days, I worked for the National Park Service in the Great Smoky Mountains of Tennessee. It was a place of natural wonders, but I decided that it was not a place for me after seeing poison ivy vines as thick as my thigh growing to the tops of mature hardwoods in all but the most dense, natural forests. It was nightmare inducing.
So what’s behind this invasion into New Hampshire? Poison ivy is a native plant, and people aren’t responsible for spreading it further, are we? Well, yes we are.
Beginning in 2006, scientists at Duke University began looking at how increased levels of carbon dioxide in the atmosphere affect various plant species. More recently, research at the Harvard Forest in Petersham, Mass., has confirmed the earlier results.
Among their findings is that vine plants, which put much more of their energy into growing new wood than do other woody plants such as trees, benefit significantly from increased CO2 levels. Poison ivy in particular was noted for growing five times faster as CO2 levels increase to those projected for the middle of this century. Any increase in CO2, such as that we have in our air today, is like a stimulant to poison ivy.
It gets worse. The potency of urushiol, the allergen in poison ivy, also increases. It’s a double whammy.
The plants grow larger and faster, and they become more poisonous. Add to this a gradually warming climate with fewer days of extreme cold in winters, and this nasty vine has no trouble moving north from its previous southern strongholds. It’s a depressing picture.
So it’s pretty clear that the rapid expansion of poison ivy across a state where it was uncommon, if not rare, is another result of our addiction to fossil fuels. Despite what some less than well informed politicians appear to believe, climate change is here, already affecting our lives, and the science as well as our daily observations confirm it.
For those of us who spend a lot of time outdoors, working on our farms or observing the natural world around us, the impacts of climate change are becoming more obvious. Only good science confirms that our anecdotal observations reflect reality, but for me the reality is that I can no longer enjoy my time outside without an additional dose of caution.
It’s not just the black flies, mosquitoes and ticks that are out to get us. Is the explosion of poison ivy part of Mother Nature’s retribution for our wasteful ways?
(Paul Doscher is a conservationist and retired environmental science professor who lives in Weare, where he owns and operates a small Christmas tree farm.)