The role of “invasive” shrubs as nurseries for desirable oak/hickory/apple tree seedlings
If there’s one thing that ecologists and farmers agree on, it’s their hatred for a handful of “invasive” shrubs like prickly ash, multiflora rose, and autumn olive. Ecologists hate them because they form dense thickets that seem to crowd out other native species. Farmers and ranchers hate them because they aren’t palatable for cattle, and, without proper management, they can take over pastures, leaving less forage for livestock. On our farm, we have a south facing hillside remnant savanna with large oak and hickory trees and a diverse understory, including many dense thickets of prickly ash, multiflora rose, and autumn olive as well as elm, ash, maple, apple, plum, hazelnut, and mulberry.
In general, our vision is to cover our farm with fruit and nut producing trees and shrubs. We also have lots of animals. Cattle, sheep, goats, pigs, poultry, deer, and turkey to name a few. The fruit trees that we want to promote, like apples and mulberries, also have super tasty leaves for animals relative to all the other species. So if you have a grazed hillside, the animals will eat all the leaves off the fruit trees before they touch anything else.
Our hillside has been grazed by cattle for decades before we got here, and sheep long before that. There are also tons of deer. As you can imagine, with all that grazing pressure, the desirable seedlings are much less prevalent than the “invasives.” At least at first glance.
For the last several weeks, I’ve been on the hillside savanna with a handsaw and a team of goats, sheep, and pigs, clearing out the prickly ash and multiflora rose (the small ruminants really like them). What I’ve found is that there are still lots of apple, mulberry, plum, oak, and hickory seedlings in the mix. They are just hidden in the brush. Lost in a sea of thorns and brambles. Then I started thinking…maybe the oaks, hickories, apples, and mulberries LIKE being surrounded by thorny “invasive” brush.
Savannas are sites of perpetual warfare between forest and prairie. Grasses and trees duke it out for valuable real estate. Thorny shrubs are the front lines of this war. Once established, they shade out the grass, break up the dense sod, and drop lots of leaves and stems, leaving behind a rich, tilthy soil. Because they form patches of dense, thorny woody vegetation, they provide a hedge against grazing and browsing animals like deer and cattle. So what am I finding nestled and tangled deep in the thick patches of prickly ash, multi-flora rose, and autumn olive? Young oak, hickory, apple, and mulberry seedlings, protected from browse long enough to get about the browse line. Without the thorny brush, these saplings would have never made it.
So today, I’m grateful for the prickly ash and multiflora rose. Our family of humans and animals will be enjoying the fruits and nuts from the trees they’ve nursed for the next hundred years. Here’s to the invasives!