The aliens are invading our hardwood forests


Japanese barberry.

Japanese barberry.

Please don't buy or transplant this nasty plant (photo above). I've written about it before but I did not have a colored photo for you. Japanese barberry used to behave itself around here, but as is the case with many invasive plants and animals, with warming temperatures in winter they are able to thrive farther north. Not long ago barberry was a problem only as far north as North Carolina.

Even so-called non-invasive cultivars, often with purple leaves, are not safe to plant. They may have fewer seeds or the flowers may be sterile, but the pollen from the flowers can still pollinate other Japanese barberry plants. Birds and other animals eat the seeds and then deposit them with a handy pile of fertilizer at the same time. Barberry can also spread by underground roots as I have found out to my dismay. I have one that I did not plant that is starting to take off. Just cutting it won't kill it.

About ten years ago there were two plants near here in maple woods where now there are two dozen, some four feet tall and beautifully bushy (see picture with green leaves). Farther south they have made forests totally impassable to humans and most animals. Unfortunately, deer mice, which immature ticks feed on for a while, thrive under the thickets. Of course deer ticks, which also need deer to multiply, are what carry the very serious Lyme disease and it is now becoming quite common in the Adirondacks. This year Moreau has a bumper crop of ticks.

Scientists at the University of Connecticut are studying what happens to the soil under barberry. It turns out that not only does the chemistry change for the worse, but earthworms thrive there. That may sound good to fishermen, but of course it is impossible to get near barberry without getting stabbed. And because earthworms are not native here since the glaciers a mile deep melted back ten thousand years ago, our native “spring ephemerals” are at risk. Worms eat the leaf litter, with the big nightcrawlers being the biggest offenders, coming up at night and pulling the leaves down into their tunnels. This leaves the ground bare, subject to erosion, and not hospitable to our native spring wild flowers. A thick cover of barberries will also shade and crowd out native plants of all kinds.

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