Pesky Worms

[john gault]

I wasn't sure if I should post this here or in the wildlife forum, but decided here since it's a question about Trail Concerns - the environment.

I've become somewhat interested in worms. I'm quite surprised about how little is actually known about this most useful of organisms. I did read a book on worms from my local library, but left a lot of questions in my mind, looking for another book. However, one intriguing aspect was the apparent damage they are doing to Minnesota's forests. http://www.dnr.state.mn.us/invasives/terrestrialanimals/earthworms/index.html

But the obvious question is, why just Minnesota? Does anyone know of any other areas, especially along the AT, that the worm is having an adverse effect on the environment?

Also, I find this a little hard to believe, from the above link:
If non-native earthworms are already here, isn't it already too late?

No. Without humans moving them around, earthworms move slowly, less than a half mile over 100 years.

Seems to me it is very dependent on the species, but they just make a blanket statement. It seems to me that the Red Wiggler (or any type worm that inhabits the leaf litter) spreads fairly quickly -- BTW, this is the species (as I understand it) that is used mostly in the composting-type privies. However, that statement may be true with respect to earth-dwelling speicies. But that's just speculation on my part.

[RWheeler]

Well, I'm no expert on earthworms and ecosystems including them, but I do know that they primarily act as decomposers, and their burrowing allows soil to be aerated and allows plants to grow better. As to why their presence would cause negative impacts on the environment, where they're not native, my best guess is that perhaps Minnesota has other important decomposers present (either animal or fungii) that full another role. The worms may be stealing that energy from other populations of organisms, which is causing them to die off, and either not feed a third population, or also contribute something else to the ecosystem. And I suppose the burrowing networks might actually impair certain species of plant life, which may be present and necessary in Minnesota, producing a similar effect of loss.

I don't know of areas where they're producing an adverse effect (in fact, wasn't even aware of the MN case), but it's truly interesting.

[john gault]

Yes the benefits are well documented. I'm curious of the adverse effects, surely if it's happening in Minnesota, it's happening elsewhere, but I haven't really found anything yet. BTW, if you read my attached link in the OP you'd think there were no native worms north of Minnesota, but that's not true, several species have been found and documented that survived the last ice age, apparently in places that were not glaciated. Here's just one example. http://www.geog.ubc.ca/biodiversity/efauna/EarthwormsofBritishColumbia.html


The problem is that information on worms is so fragmented and contradictory. I've found information in some sources that blatantly contradicts other sources. Just a tough subject to read up on.

[RWheeler]

I think the issue with that is that there are a lot of different species of earthworm, each processing different nutrients and animal/plant matter. It's hard to really know exactly what populations exist in an area unless you excavate the entire area... and anyone studying the impact on an environment wouldn't do that.

[rgarling]

Perhaps there just isn't very much to do in the snowbelt of Minnesota. I read one of the studies and it sure felt like they were reaching (fitting curves to the data, just because they could). To my eye, a HORIZONTAL line was a more appropriate fit for each of their parameters (meaning no effect) except for herbaceous plant richness and herbaceous plant Shannon diversity for which there was a positive relationship. (more worms more richness, more diversity)

[john gault]

I'm a little skeptical, but that isn't saying much since I never believe anyone:D I'd really like to go look at these locations, got some questions on those pics, but would really like to hear of other worm studies in other areas, still looking...

[Lyle]

Highly suspect.