Some earth worms may need to get off their duff…

Duff is another term for litterfall... the dead plant material like leaves, bark, twigs, nuts, and seeds that fall on the forest floor. Forest ecology can be dramatically affected by changes in the litterfall or duff layer.
In my previous post about litterfall – a question was posed by barefoot heart:

     I’m curious to see how you answer this question. 
     I’ve keyed in my answer and invite you to join me in this POST POLL before reading any further…
How are the stats looking in the Poll?

My guess is… how you answered this poll depends on where you live. Folks who live in northern Minnesota, Wisconsin, New York, or parts of Canada near a temperate zone hardwood forest area are more likely to have seen invasive worm stories in the news. Research is showing the regions most affected seem to be previously earthworm-free temperate and boreal hardwood forests.

“What,” you may ask, “areas that were earthworm-free? How is that possible?”

Cindy Hale, a research associate with the Natural Resources Research Institute of the University of Minnesota, is one of many researchers who agree on the following explanation. After the last ice age, native forest ecosystems like those in the western Great Lakes region adapted to earthworm-free conditions after retreating glaciers wiped out native earthworms. These forests were devoid of earthworms until European settlers came to America. Many of the early sailing ships had earthworms in ballast soils and in earth used to transport plants to the New World. More recently, earthworms have been spread by timber harvest, fishing bait, and using worms for composting. No matter how they have been spread, earthworms in forest ecosystems create destructive consequences by altering carbon and nitrogen cycles. Forest decline syndrome occurs when litterfall or duff is reduced in bulk and composition due to earthworm activity and unable to support healthy understory flora and fauna.

A quick and interesting video!

Please watch this short video to see how invasive worms are impacting forest ecosystems, and to learn a simple way to curb the spread of invasive worms.  If you like to go fishing…this is something you could easily do.

I was curious!

After viewing the video, I was curious to know:

  • Is the litterfall (duff) in the forest next to my home invaded by worms?

Although the Worm Watch website gives VERY scientific criteria for measuring worm density, diversity, and biomass– I opted to try a less complex approach to gauge the ease of finding earth worms in our forest. If large numbers of worms were located, I would have ramped up my investigation to a more scientific method oriented scenario. I dug 12 test spots and came up with zero earthworms in all but two locations. In the two locations that produced earthworms, there were only  two worms in each soil clump. A more extensive hole was made in a nearby location to see how the litterfall (duff) layer interacted with the soil below.

It appears the litterfall/duff layer in our forest is still thick and that a clear delineation exists between the duff and soil layers. The big difference between the Beaver Willows forest area and the forests that are being compromised is that our forest is primarily coniferous with Red Alder, Oregon Ash, and Willow intermingled. I wonder if regions in Oregon that are typically Oak groves are in danger of invasive earthworm ecosystem disturbances.

Research is showing that invasive earthworms in temperate hardwood forests can have a negative impact to forest health. These are the earthworm invaders that need to get off their duff… the sooner, the better.

Webliography:
  1. Great Lakes Worm Watch; http://www.nrri.umn.edu/worms/; accessed 01/27/14.
  2. National Science Foundation; “Invasion of the Earthworms;” http://www.nsf.gov/news/special_reports/science_nation/wormwatch.jsp; accessed 01-27-14.
  3. BBC Nature; “Earthworm Invasion: Aliens Causing More Harm Than Good?;” http://www.bbc.co.uk/nature/19646548; accessed 01-27-14.
  4.  Amy Stewart; “The Earth Moved: On the Remarkable Achievements of Earthworms”

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