By now, my readers must think this little forest is an earthly paradise, packed with native plants and animals. The truth is rather different – I’ve only been showing you the good bits. The 20 acres or so now relatively free of invasive plants have been hard won, and some will not agree with our methods. Every acre restored has first been subjected to intensive “management” of the chemical sort, year after year. And there’s a lot more left to do.
A friend who teaches at the Nature Center used to greet me by asking what I’d killed today. The question really irked me since my main goal was restoration, and I much preferred planting things to terminating them. But thanks to the USDA (US Dept.of Agriculture) I’ve now become a professional killer of invasive plants.
A little background – about 10 years ago much of this forest looked like the image above. Scattered, very large Bush honeysuckle (Lonicera maackii) shrubs dominated the understory and almost nothing grew in the deep shade below. Although a couple of us were working to cut them down, progress was very slow. Starting in 2018, we obtained our first three year contract with the USDA Environmental Quality Incentives Program,(EQIP). Landowners and farmers are offered reimbursements through his program for various practices that benefit the environment, in our case the removal of invasive plants.
“Removal” is of course a euphemism for killing, and the contract specifies just how it has to be done. First year – cut stump treatment with herbicide applied to the cut end. Second and third years – herbicide foliar spray all new invasive shrub growth. Two consecutive years (at least) of spraying are critical, since the release from shade stimulates rapid new growth.
At one time I harbored the naive belief that just cutting down the Bush honeysuckle would result in a vast improvement. In the case of this urban forest, it’s more akin to opening Pandora’s box. What comes out is everything that’s lain dormant in the seed bank, waiting for the light.
My only backpacking adventures these days are with a backpack sprayer, the indispensable piece of equipment for invasive plant management.
Solid stands of shrubby invasives like the Privet (Ligustrum spp.) above, are relatively easy to spray.
It’s more difficult when spring wildflowers like these Mayapples are interspersed, but I’ve managed to skirt around the patch with its huge umbrella-like leaves.
There is undoubtedly some “collateral damage”, since Solomon’s seal, Pawpaw and Jack in the pulpit are common in the spray areas. To avoid them I have to stay very focused, and the work goes slowly.
If I’ve succeeded, a week or two after spraying there are a lot of dead plants.
The good news comes later – a year after Privet foliar spraying the site above has improving diversity, and a nice sowing of Virginia wild rye helps speed the recovery.
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I’ve been wanting to write this post for awhile. Speaking with visitors, I realize that few people know what’s happening to forests, particularly those near urban areas. For a lot of folks if it’s green it’s good. And the terminology is problematic – “invasive”, “native vs non-native”. It’s hard to even explain the problem without seeming like a botanical xenophobe.
I resist the habit of calling invasive plants bad, since they’re as good as any other plant in the ecosystem where they evolved. The traits they have in common – rapid growth, hardiness, abundant flower and berry production – led to their selection as horticultural varieties in the first place. It’s these same traits that allow invasive plants to take over ecosystems, particularly damaged ones. This forest was used for agriculture and livestock grazing until the mid 1900’s, so was left in a vulnerable state. “From 1960-1984 the US Department of Agriculture promoted Bush honeysuckle and developed so-called “improved” cultivars, selecting for traits such as increased fruit production that further contributed to its invasive potential.” (Missouri Botanical Garden)
The inability to share space with native plants is a characteristic of most invasives. As a result, heavily invaded natural areas lose the diversity of plant species needed to uphold a healthy, resilient ecosystem. Privet, used for hedges because of its dense branching habit, excludes pretty much everything else when it grows in the forest. It might seem like good wildlife habitat, but the weak, twiggy architecture is not preferred by birds.
In contrast, the native shrub Coralberry (Symphoricarpos orbiculatus) has an open growth habit. Sunlight can reach the ground, allowing herbaceous plants and young trees to intermingle and find shelter from herbivores.
A rapidly spreading takeover by Wintercreeper, Euonymus fortunei. This evergreen groundcover excludes much of the herbaceous layer, and prevents germination of young trees with its thick waxy leaves and dense root system.
In contrast, an average little plot of partially shaded forest floor without Wintercreeper supports at least eleven species of herbaceous plants.
One more compare and contrast – the image above shows a typical scenario in this forest pre-invasive plant removal. Large Bush honeysuckle and Asiatic bittersweet vines exclude so much sunlight from the forest floor that most trees and herbaceous plants can’t grow.
This recovering section of woodland is developing a dense understory layer, just what you want to see in a young forest. A wide diversity of plants means there is something to occupy every spatial zone from ground level to ten feet. The habitat value is high, and the native plant density helps prevent reinvasion.
To sum it up – despite the unpleasantness of herbicide foliar spraying, when used carefully it’s a very effective management tool, and the only one we have. I’ll just have to accept that I’m a killer as well as a restorer.