By Pamela Doan
As I research and study issues about gardening and climate change, I’m constantly assessing my own practices and landscape, i.e., freaking out/judging myself/shame-spiraling/vowing to do better.
While I have a lot of boxes I can check, I’ve always been overwhelmed when it comes to the 75 percent of my landscape that is forested. For one thing, it doesn’t require my attention in the way that landscaping and vegetables do. I don’t water, weed or prune anything. We keep a trail clear, but otherwise it’s on its own.
It’s a sadly typical forest that isn’t thriving, though. There’s not much between the tops of the mature trees and the ground level. Deer browsing has wiped out the next generations of younger trees, seedlings and native plants. What the deer won’t eat thrives and that’s how Japanese barberry (Berberis thunbergii), a thorny, mean, fast-spreading bush can dominate the forest floor. As an added offense, barberry leafs out in the spring before any of the native plants and blocks the sunlight from other species, keeping any plants that escaped the deer from growing.
While most of the forest is sugar maples, the largest tree is an Eastern white pine (Pinus strobus). In its natural habitat, it’s a far different tree than the pines planted in yards as hedges or privacy barriers. Although white pine forests used to cover this area, now trees are most often planted in rows and closely spaced. They will never achieve the soaring glory and shape of this white pine, allowed to reach its potential. Because white pine is the tallest tree that grows in New York, landscaping with one is a big choice for most yards.
White pines can live up to 450 years and measuring it can reveal its age. I recommend finding a helper if you want to try this. My solo experience involved duct tape, walking on top of an unstable, slippery rock wall and some bruises. After two tries, I settled on 52 inches as the diameter. Yes, that’s more than 13 feet around and 4 feet in diameter.
The Minnesota Department of Natural Resources published a growth factor rate for trees and listed the white pine with a factor of 5. Here’s the formula, using my tree as an example:
Measure circumference = 164 inches
Divide circumference by 3.14 = 52 inches (This is the diameter.)
Multiply diameter by growth factor = 52 x 5 = 260 years
Maybe. This is not a perfect method and I am not a perfect measurer. I can confidently say that it is an old tree, however.
Taking things further, I tried two websites — iTreetools.org and treebenefits.com/calculator (easier) — to learn more about all the contributions this tree is making. In a year, it reduces greenhouse gases by 323 pounds and intercepts more than 2,600 gallons of storm runoff as its roots hold water in the soil.
Understanding just this one tree and its history and environmental benefits motivates me to do more to help my parcel of forest be more than a heavily browsed, invaded landscape.
For a spring project (after I’ve measured all my trees!), I’ll look for native plant and tree seedlings from the county soil and water conservation district plant sale. While planting 8 acres isn’t feasible, doing small sections each year and protecting seedlings until they’re tall enough to withstand hungry deer could be. Using native perennial seeds is another low-cost way to repopulate what’s been lost.
If you see someone around town measuring a tree’s circumference, it’s probably me. Spreadsheets might be involved, too.
Pamela Doan, a garden coach with One Nature, has grown ferns in Seattle, corn on a Brooklyn rooftop and is now trying to cultivate shitake mushrooms on logs. Email her at [email protected]