Some of us own homes in woodlands, and do so for the privacy and to enjoyment they give us. When you point out to people that much of what they see is Buckthorn, they might say that Buckthorn is part of nature too. Why not enjoy it as one plant among others? The answer is because it is invasive.
All plants come from particular biomes or ecosystems which make up a network of plants, insects, micro-organism, and animals that keep each other in check.
Invasive plants and animals are species that have been taken out of their network of plants and are in a context in which there are no constraints. Whether its the wild boars of Texas, or the kudzu of Arkansas, or the zebra muscles in the lakes of Minnesota, these animals, plants, and mollusks are invasive because they have no predators to keep them in their place.
Nature tends toward diversity. Biomes often see an expansion of species as species evolve to maximize niches in an environment. This tendency toward proliferation of species, and how they work together to form an ecosystem is, in great part, what makes nature interesting, as well as what makes it work. Invasive species throw a wrench in this project of plant diversity by dominating and replacing them.
These three oaks in our wetland are remnants of an Oak Savanna biome. A closer look under and behind these oaks shows the results of thirty years of unchecked Buckthorn growth. The Buckthorn thicket under these trees is so dense that neither deer nor humans can traverse it. The Buckthorn has the ability to inhibit the growth of other species, including the Bur Oaks, so much so that little else grows in this area. When the Bur Oaks die, there will remain a Buckthorn canopy that reaches a final height of about 25 feet.
If nothing is done, there will be a dramatic reduction in diversity. In effect, the Oak Savanna biome will be undone. So, we here on the farm continue to pick away at removing Buckthorn.
Another challenge is that after it has been removed, Buckthorn often comes back. Mature Buckthorn plants put out a lot of seed in berries, which birds eat and spread through their droppings. This seed can remain viable in the soil for up to five years.
This is why removing Buckthorn should be part of a restoration program--a plan to restore the woodland with native plants and through prescribed burns, a program we will save for another post.