From the New York Times by Anne Raver
I have the perfect example of right plant, wrong place: the black locust trees marching like a green army across the beautiful meadow on our family farm in Maryland.
Don't get me wrong. I love these locust trees, with their tall, straight trunks, deeply furrowed gray bark and blue-green compound leaves that cast dappled shade. Their pealike white flowers bloom in late May, redolent of honey.
But to see so many locust trees covering a third of our favorite field, and know that we played a part in their proliferation, is alarming.
Five years ago, we signed up for a federal program that subsidizes landowners for taking cropland out of production, and planting it with native grasses. The idea is to keep pesticides and nitrates out of the watershed, and to control erosion.
I was all for this experiment: With pesticides gone, I pictured songbirds and pheasants nesting among the big bluestem and Indian grass, frogs and peepers singing again in the wet meadow. They had all disappeared a few years before, possibly from pesticide use.
I didn't realize at the time that changing the old regimen of spreading herbicides and chemical fertilizers on land degraded by continuous cropping would open the door to a surge of locust trees, a pioneer species eager to conquer new territory.
My brother Jim, who is a doctor, was skeptical. In the 1940's, he had helped plant hundreds of multiflora roses in our pasture, when the federal Agriculture Department was touting the shrub rose, a native of Japan, for erosion control and natural fencing.
Before long, cows grazed between hedgerows covered with white roses. The downside was that the roses jumped into the fields and woods, spread by birds who gobbled up the rose hips and defecated the seeds.
To my mind, however, the warm-season grasses would be benign. And the farmers who care for our fields were more than willing to do the work, if we handed them the subsidy. So we did.
At first, the annuals put on quite a show: red poppies and blue cornflowers all ablaze. The next summer, the perennials, like purple coneflowers and yellow coreopsis, bloomed. Tall mullein sent yellow fuzzy spikes into the air. The third year, the big bluestem took hold, as blue as its name. There were bluebirds on the edge of the woods, grasshopper sparrows in the fields, hawks swooping for mice. And the stream was so clear.
A few years ago, however, after heavy spring rains followed three dry summers, we noticed young locust saplings, by the hundreds, sprouting on the hilly side of the broad meadow that slopes down from a woods to the stream. By taking the field out of production and ceasing disking of the soil and using herbicides, we opened the door for nature - in the form of locust trees - to reassert itself.
Not to worry, our farmers said. They would just mow the saplings down in the winter, when they always mow the meadow. But the next spring the trees reappeared, thicker and taller than ever.
Cutting them, it turns out, encourages more shoots, because they have an aggressive root system. "If you knock them down, they come back tenfold," Bryan Butler, my local agricultural extension agent, said. The native black locust tree, Robinia pseudoacacia, is one of nature's ways of restoring disturbed environments. A member of the pea family, the black locust has roots with nodules full of nitrogen-fixing bacteria, which convert nitrogen from the air to a form usable by plants, thus allowing locust trees to thrive in degraded soil.
A pioneer species like locust trees infuses the soil with nitrogen, making way for oaks, red maples and many other plants that compose an Eastern forest. Our meadow, in other words, is trying to return to the woods it once was, before our ancestors cleared it for cropland and pasture.
HEAVY rains last fall and winter made the fields too sodden to mow. By early April, the locust trees were 10 feet tall. Because mowing would just make them come back more thickly, I asked the farmers to skirt the grove of young locusts.
"I'll go in with my loppers, and paint the stumps with Roundup," I said confidently. "I could use them as tomato stakes or gate posts." My friend, Rock, looked at me as if I'd lost my mind. There are some 3,000 locust trees in that field.
And we don't even like to use Roundup, an herbicide widely considered to be safe.
Last week, I spent all morning cutting down a handful of locust trees. Within hours, the heat, the effort and the sheer magnitude of trees defeated me. I would need an army of gardeners to remove them. Come next winter, after the birds have finished nesting, I'll ask the farmers to mow. That won't kill the locusts; it might, however, keep them in check.
And if we ever stop mowing, the locusts will win, and lead the cycle back to woods. These trees have taught me a lesson: once you tamper with nature, it's a long road back to working alongside it naturally.
