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Re: [compost_tea]non-native species of earthworms



Hello-
This reminded me of an article I had in my old Soils notebook from school. 
Unfortunately, there's no date.

"An article by Will Nixon in American Forests (Box 2000, Washington 
D.C.  20013) reports that forest ecologists are noting a striking lack of 
understory growth in urban and suburban forests in the New York 
metropolitan region. While rural forests have a constant supply of tree 
seedlings ready to replace the older trees, these were not seen in the 
urban-suburban woods.

Also missing were many of the shrubs and groundcovers wildflowers found in 
rural woodlands. The original ecosystem was destroyed, just as occurs after 
clear-cutting; the University of Georgia recently found that 90 years after 
clear-cutting of woods in the Southern Appalachians, trees had grown back 
but there were no trilliums, ginseng, or other herbaceous plants found in 
old-growth forests.

The New York researchers report that non-native species of earthworms had 
invaded the urban-suburban forests. These decompose fallen leaves in a year 
instead of the five or more years it takes fungi to do the job in rural 
forests. One result of the rapid duff decomposition is the production of 
large amounts of ammonium. Bacteria convert this into nitrate, which may 
encourage the growth of species that thrive on this type of nitrogen, such 
as the Norway maple which is displacing native species in many northern 
forests.

Much more research remains to be done. The crucial question: are earthworms 
the primary cause of this major change in urban-suburban woodland 
ecosystems, or do they simply move in when something else destroys the vast 
network of fungal filaments that digest the leaf litter layer?"

Autumn

At 05:31 PM 6/2/03 +0000, you wrote:
>just some information I thought I would pass on
>Worms in North America died in our last ice age. We did not have
>worms till the Europeans brought them over in the soil from the many
>plants they brought over.
>
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