Don: No, they don't leave any direct traces that we know of in the sedimentary record. However, they do cause chemical and erosional changes in the soil that might show up in the sedimentation process. If so, no one has worked it out yet. It is also possible that some earthworms could be preserved in sediments as macrofossils--we have tree leaves that a several million years old, so the same could happen to earthworms, but no one has uncovered such fossils for the glaciated parts of North America.
Lee DON BERTOLETTE wrote: > Lee- > Yeah, I guess it's not like earthworms leave much in the way of > skeletal remains...is there anything in their innards that their > remains or 'castings' might yield identifying signatures? > -Don > > > Date: Fri, 7 Aug 2009 09:51:38 -0500 > > From: [email protected] > > To: [email protected] > > Subject: [ENTS] Re: earthworms and invasive plants > > > > > > Joe: > > > > Much of the earthworm literature states that earthworms were removed > > from the northern states by glaciers and that the worms never returned, > > and/or that North American species of earthworms can't live in > glaciated > > areas. > > > > However, there is no evidence for those statements. I have never seen > > any proof that earthworms lived in the north prior to the last > > glaciation, or that it takes more than 12,000 years for the earthworms > > to move about 1200 miles from the areas where they would have lived > > during the peak of glaciation, to places like MA, NH and MN. So, I > think > > that they essentially reached the limit imposed by colder climates as > > they moved north. > > > > The correlations between whether an area is glaciated and native > > earthworms are present also does not hold up very well. Southwestern > WI, > > for example, was not glaciated and has no native earthworm, whereas > > Southeastern WI was glaciated and does have two species of native > > earthworms. In addition to that, tundra and boreal forest with > > permafrost would have extended as far south as TN and NC at the peak of > > the last glaciation, and no North American earthworm species would find > > those habitats suitable, so they had to move a great distance just to > > make it back to places like MA and WI. I think earthworm ecologists are > > not very good paleoecologists, and look at the world as static, leading > > to their misinterpretation of glaciation versus earthworm presence. > > > > Lee > > > > J --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
