Thursday, 4 Sep 2003

MINNEAPOLIS, Minn.

In my introductory conservation biology textbook, David Ehrenfeld, professor of biology at Rutgers University, advised conservation biology students like me to: “Minimize the logistic complexity of your research.” I have truly strayed from his advice.

Earthworm Andy inserts electrodes in preparation for earthworm shocking.

This morning I am scheming about ways to find volunteers to help me extract as many earthworms from the ground as possible. Here is my version of research logistic complexity: find a large crew of willing helpers to dig 250 yards of two-foot-deep trenches by hand, bury large sheets of metal to form an underground wall in these trenches, plant 1,200 plants in these plots, haul a 4,000-watt generator a quarter-mile into the forest, build large arrays of metal electrodes, insert these into the plots, turn on the generator, collect every earthworm that comes to the surface, maintain a steady supply of volunteers to help for 10 days of worm “shocking.” Repeat in the fall, the spring, and the fall again. And remember the golden rule: don’t electrocute anybody.

I have to admit, part of me likes the logistics of research. I like working with volunteers. In fact, I just decided to recruit volunteers from among students I teach at the Twin Cities Environmental High School. I like building various contraptions. Logistically complex it is. But at least I have heeded one of Ehrenfeld’s points: “Include the participation and wisdom of the local community.”

A dedicated volunteer collects earthworms as they emerge from the shocked ground.

Shock worms from the ground? Why?! My plant census yesterday at Wood-Rill Scientific and Natural Area showed what we have noticed for six years. Even when we have completely excluded deer from parts of the forest, the understory plant community has recovered minimally. Could invasive nonnative earthworms be preventing native plant recovery? Remember, as I discussed on Tuesday, until 100 years ago (or less) there were absolutely no earthworms in this forest. It went from zero worms per acre to more than 1.5 million per acre! They have massively altered the structure and other properties of the soil. We know that they can dramatically reduce native plant density and diversity as they invade a previously worm-free area (check out a diagram for more info). But can we reverse these effects if we remove them from an area? So that is what I am doing — removing up to 60,000 earthworms from half of the plots and comparing plant growth in these plots to ones where we did not remove the earthworms.

Volunteer plantings help determine how earthworms affect forest growth.

Thankfully for me, I can always get volunteers to come out for worm shocking. It is amazing to see the ground seethe with worms as they escape the small electrical current. This technique has broader appeal too. Last spring the evening TV news even covered the work. This attention helps to spread awareness about an important issue affecting our forests. And don’t worry — the worms are not hurt by this. We pick each one up and release them under the fruit trees on campus.

It was a late night last night. I organized my data from yesterday’s plant census, prepared data sheets for today’s census, and responded to some emails about a symposium that several of us are trying to organize. Should it be approved by the Ecological Society of America, the symposium will convene many academic researchers who study the ecological effects of nonnative earthworms in ecosystems around the world.

Four years ago I would never have expected to be so consumed by this research topic. But I think it illustrates many interesting challenges for habitat conservation and conservation education. I am looking forward to working on that component of my work tomorrow. For now, I am off to the field once again to monitor plant growth in the worm-shocking plots.