Our forests are transforming right before us

Just before the leaves started to turn color and drop to the ground, I wandered around the woods in my backyard and saw something I hadn’t seen in many years. Sunlight was streaming through the canopy and creating large bright patches on the forest floor. What had once been completely shaded during the growing season was no longer as I remembered.

            So I investigated each site, worried that someone had illegally cut down some of the trees on my property. I shouldn’t have been concerned, because what I found was completely

natural. It’s a process that foresters and biologists call succession, and it’s been happening here and in every forest everywhere since the first forests grew. Trees die – whether from disease, age, storms or from beavers or humans cutting them down – and when that happens, sunlight penetrates the forest floor again and new growth emerges.

            In the new patches of sunlight, I found waist-high shrubs of sweet pepperbush, spicebush and mountain laurel where only ferns and mushrooms had previously grown. The sunlight had allowed such rapid growth of new plants that the abundant deer in the area, which had suppressed the growth of so many understory plants, hadn’t been able to keep up.

            As in much of the forested parts of Rhode Island in recent years, the dead trees that led to this new growth were the result of the voracious appetites of gypsy moth, winter moth and forest tent caterpillars. The Rhode Island Department of Environmental Management says that as much as 25 percent of the state’s forests were killed by the insect pests during a three- or four-year period. As in my yard, the dead trees appear in patches scattered across the landscape rather than in large continuous swaths, which means that every forest owner was probably affected, but only in a limited way.

            What’s going to happen next is a big question. The shrubs that grew up in the sunny spots will only grow so tall, and eventually trees will sprout and fill in the canopy and shade out the shrubs, just like it always has. But what tree species will they be? The iconic ones like oaks, maples and birches that used to be there, or something else?

            Local foresters tell me that it’s probably going to be something else.

            New varieties of invasive pest insects are arriving in our area and killing targeted tree species. One is expected to kill all the state’s ash trees in the next decade, another has already wiped out most of our hemlocks, and still another may take out our oaks, just as diseases wiped out all of our chestnut and elm trees long ago.

Scientists believe that these infestations of tree-killing pest insects are likely to worsen in years to come, but that doesn’t mean the forests will become unhealthy. They’ll just change, like so much of the rest of our environment. The changing climate will likely spur the growth of tree species more acclimated to warmer temperatures – like black cherry, yellow poplar and southern varieties of oak and hickory – replacing many of our old favorites.

So don’t fret too much over those dead patches of trees you see across the landscape. Instead, appreciate how the natural process of succession is already stimulating new growth in those patches. And then imagine what that forest will look like a generation or two into the future. It almost certainly won’t be akin to what your grandparents saw.

This article first appeared in The Independent on Oct. 24, 2019.