Thursday, July 23, 2015

How you live -- Invasive species

Our "How you live" bioregional quiz question number four, and my attempts to answer the question(s) illustrate some of the fascinating issues that crop up when we try to define a bioregion. To refresh your memory, here's the question(s):

List three invasive species in your region.

What [sic] is the most damaging to the ecosystem?

I know Minnesota has invasive species. There's often a newspaper story about "pulling buckthorn" or some new zebra mussel infestation. I went looking for a more comprehensive, you know, "official" list. Ha!

Birdsfoot trefoil, a Minnesota invasive plant
Birdsfoot trefoil, a Minnesota invasive plant  It is still sold commercially.
Photo by J. Harrington

Here's a state level listing of Minnesota's invasive plants, as listed in the Early Detection and Distribution Mapping System. As far as I can tell, this database, which also includes lists for invasive insects, diseases and wildlife, doesn't allow for retrieval of its information across categories by county. Not to worry though, Minnesota has its own Invasive Species Advisory Council. They provide information on and links to lots of other fragmented listings of terrestrial, aquatic and other invasive species and a ranking of threat that fails to identify which species fit which ranking. Nationally, the community of academics, agriculturalists and natural resource types responsible for managing and/or eradicating invasive species needs lots more good to great information architects and database programmers.

I tried searching closer to home, since I had seen several references to county-level invasive species responsible individuals. The contacts are Agricultural Inspectors and we have a Noxious Weed Appeal Committee on whose web page is a link back to the Minnesota Department of Agriculture's Noxious weed list, which lists my buckthorn as a Restricted Noxious Weed, "whose only feasible means of control is to prevent their spread by prohibiting the importation, sale, and transportation of their propagating parts in the state except as allowed by Minnesota Statutes, Section 18.82." See how straightforward this is. Let's return to the question.

List three invasive species in your region.

On my property, I know I have buckthorn growing. Here's the Minnesota Department of Natural Resources statement on buckthorn:
Why is buckthorn such a problem?
  • Out-competes native plants for nutrients, light, and moisture
  • Degrades wildlife habitat
  • Threatens the future of forests, wetlands, prairies, and other natural habitats
  • Contributes to erosion by shading out other plants that grow on the forest floor
  • Serves as host to other pests, such as crown rust fungus and soybean aphid
  • Forms an impenetrable layer of vegetation
  • Lacks "natural controls" like insects or disease that would curb its growth
I also have dame's rocket growing. That doesn't seem to be on the agricultural noxious weed list, but it is listed in the Forest Invasive Plants Resource Center, and in the mid-Atlantic NPS listing Is it or isn't it an official "invasive species" in Minnesota. Beats the hell out of me. We do usually pull it after it's flowered and before it goes to seed.

dame's rocket, a Minnesota invasive plant?
dame's rocket, a Minnesota invasive plant?
Photo by J. Harrington

In our region, there's lots of people really upset about several species of Asian carp invading both the Mississippi and the St. Croix rivers. I imagine they probably have the biggest potential to impact the economies around here, but I'm less sure about their effects on the ecosystem. In fact, it's probably obvious that I'm frustrated by the lack of a coherent, consistent listing of "invasive species." I'm even more frustrated by the lack of studies on the ecological roles usurped by invasives, their effects on an ecosystem, more than "competes with natives for resources." I don't have a good answer to the second question and I'm not even sure where to find one.

My Species

By Jane Hirshfield 
a small purple artichoke
in its own bittered
and darkening
grows tender,
grows tender and sweet

patience, I think,
my species

keep testing the spiny leaves

the spiny heart

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