Springtime means the return of growing season! As spring ephemeral wildflowers begin to bloom and trees begin their annual bud break, the NWALT stewardship team begins gearing up for invasive plant management across our preserves. Control of exotic and invasive plants is a perpetual effort- eradication is a word we cast into the fire long ago. Being close to an urban center, with its backyards and roadsides and history of introducing foreign vegetation into the landscape makes for an endless supply of seeds to start new infestations. And properties we’ve worked on for years (looking at you Wilson Springs Preserve) seem to have an eternal seedbank of headache-inducing exotic plants which rise like phoenixes every time we clear an area or open a bit of tree canopy.
Efforts typically begin with the annual “Culling of the Callery Pear.” One of the first trees to bloom in our region, this Asian species is easy to spot in a landscape still brown and grey from the chill of winter. When the weather is warm enough, we can perform hack-and-squirt, a technique for woody plant control that is exactly as it sounds. Using a hatchet, cuts are made through the bark into the cambium layer- that mysterious area between xylem and phloem from which plant stem cells grow. Once cuts are made, a small dose of herbicide is sprayed into the tissue, delivering a shot of sweet vengeance into the system. Callery Pears, with the cultivar “Bradford” being the most well-known, are generally not self-compatible, meaning they don’t regularly produce fertile seed when pollinated with others of the same cultivar. When different cultivars are planted within close proximity to each other, that’s when the trouble starts. Fertile seeds are bombarded by birds throughout the landscape and grow aggressively, creating thickets, outcompeting native plants, and producing more fertile seeds. The cycle continues, and stewardship staff rest easy in their job security.
Another exotic invasive plant stewardship staff target each spring is the dreaded poison hemlock (cue Janet Leigh). Yes, the same plant Socrates was made to consume for corrupting the minds of ancient Athenians is itself a corruption on our North American landscape.
A fully mature Poison Hemlock
Hailing from Europe and North Africa, this steroidal member of the carrot family can grow to 8’ tall and is deadly to some livestock and potentially fatal to people. It’s an aggressive spreader and biennial.
In its first year it sends up a small rosette, not unpleasant, with carrot or parsley like foliage. It often pops up along roadsides, in pastures, or in other disturbed areas. In its second year, it shoots a towering multibranched purplish stem with white flower clusters similar to Queen Anne’s Lace. But don’t cut this for your living room vase. The sap can cause severe rashes and even failure of the respiratory system! NWALT stewards target the first-year plants and either dig them up or hit them with a targeted squirt of herbicide. This limits staff contact with the plant and helps preserve native plants around them. Rather than whacking second year behemoths down, we try to prevent them from getting to that stage in the first place. Along with being toxic, poison hemlock spreads quickly and creates early spring monocultures devoid of beneficial flowering herbs, often the first food source for our native pollinators. Do it for the bees, dang it!
The task of controlling these and dozens of other exotic and invasive plants on NWALT preserves looks quite daunting when schedules are drawn up and white boards get crayoned with springtime to-dos. But with solid planning, and an ecologist’s pension for protecting, preserving, and proliferating native plants, we jump right in with vigor every year. Though we often feel like Sisyphus, pushing mighty green shrubs uphill for eternity, there is immense satisfaction in seeing areas once overrun with invaders become new havens for native plants and wildlife. The hours we spend controlling these plants now, will come back to our children in hours of enjoying a native-ish if not entirely native landscape. Restoring and preserving habitats throughout Northwest Arkansas is crucial in protecting our natural history here. Invasive plant control is just one part of the puzzle. Often frustrating, but always rewarding, the work of habitat restoration continues, and seeing a bit of prairie or woodland explode with native flowers each spring makes it all worth the while.