In March and sometimes in early April, the high-quality native deciduous woodlands of Illinois still look a bit wintery. Tree trunks are shades of gray and the leaves on the forest floor are variations of brown. True, buds are preparing to unfurl their leaves and wildflowers are emerging, but a springtime woods is not vibrant green, unless its understory is populated by the highly invasive exotic plant, bush honeysuckle. A green leafy woodland understory appearing before spring is not a good thing.
Bush honeysuckle, Amur spp., “leafs-out” or foliates before the oak, hickory, and maple trees do. Even though bush honeysuckle grows to a height below the trees’ canopies, the honeysuckle’s bright green leaves are able to gather ample sunlight while trees are still bare in early spring. Plenty of sunlight ensures vigor and growth for this highly invasive exotic species and translates into problems for forests.
The good news is that headway is being made in efforts to eradicate exotic invasive plants at state-managed forested areas across Illinois.
Vividly evident now is the efficacy of a surprising strategy in woodland management. Fire! Yes, prescribed fire regimes appear to be proving their worth, and a visit to Sam Parr State Fish and Wildlife Area (SFWA) near Newton will allow you to see for yourself.
Sam Parr SFWA’s site superintendent, Jim Gillespie, is encouraged by results, “Certain sections of the forest have been burned repeatedly over the last ten years – most of the prescribed burns taking place in the fall – and reduction in the number of honeysuckle bushes is remarkable.”
Pointing to an area lying east of a park lane, Gillespie commented, “The understory of this woodland section, which has not been burned in recent years, is definitely dominated by green leafy bush honeysuckle. But, take a look at that section, most recently burned in November of 2016. Notice the reduction in honeysuckle.”
Observations about the woodland section which had been managed by controlled burning include “an open, park-like appearance” and “a wildflower-blanketed forest floor.” Charcoal-like residue attests to fire which had spread through fallen leaves and twigs and up into rotting trunks or snags and yet had stopped at a pre-determined boundary. The twigs of hickory and oak trees, with fire-blackened bark at their bases, are bedecked with buds, alive and well. Visible are only a few leafy honeysuckle bushes and just a scattering of honeysuckle sprouts.
Roger Jansen, the IDNR natural heritage biologist for our area, attests to the effectiveness of fire as one step in forest management. “The use of frequent fire can reduce exotic shrubs such as bush honeysuckle in forest understory. This is only the first step.” He indicated that multiple management techniques are needed. “The more open the understory and the forest canopy the more likely you will get oak regeneration and a healthy forest.”
Standing in a woodland section burned in February, Gillespie pulled a honeysuckle sprout, revealing an extensive shallow root system. “Bush honeysuckle prevents wildflowers from acquiring adequate sunlight during early spring which is the opportune time for their growth. Also it has allelopathic properties, meaning it can release into the soil a chemical that negatively affects the growth of other plant species.”
Wade Bloemer, IDNR district forester, explains why wildflowers are an important part of a forest’s natural community and are a benefit to wildlife. “The insect pollinators, bees and butterflies, utilize the nectar of wildflowers. Insects feed upon the herbaceous layer at the forest floor, and still others, such as spiders and praying mantis, hunt insects. The food chain continues.”
Within Sam Parr SFWA’s well-managed woodlands, this summer when a wild turkey hen and her brood of little turkey poults are searching for protein-rich food, it will be there in the form of insects, chiton-wrapped energy packets.