Repeated freezing and thawing (i.e., the formation and destruction of ice
crystals in the soil), other burrowing organisms, and the growth and
subsequent rotting in-place of plant roots all help keep soil loose in zones
where the cold excludes earthworms.
Martin Meiss
2010/5/3 William Silvert <[email protected]>
> Perhaps Bruce could fill us in on earthworms, since not all of us are
> knowledgable in this area (I'm a marine ecologist and obviously picked up on
> some inaccurate ideas). I always assumed that they played the same role as
> some key polychaetes do in benthic systems, where it has been shown that if
> just one key species is eliminated the bottom turns to concrete.
>
> So please: if earthworms are absent, what keeps the soil aerated and broken
> up? What are the detrimental impacts of the undesirable earthworm species?
> What is the range of ecosystem functions that earthworms play?
>
> Bill Silvert
>
> ----- Original Message -----
> From: Bruce A. Snyder
> To: William Silvert
> Cc: [email protected]
> Sent: segunda-feira, 3 de Maio de 2010 18:41
> Subject: Re: [ECOLOG-L] State Microbes and Yucky Worms
>
>
> Native Nearctic earthworms have not been eliminated and are quite diverse.
> Pleistocene glaciations did extirpate them from the northern portion of the
> continent, and the present-day ecosystems in this region developed just fine
> without the presence of earthworms. This is where the detrimental impacts of
> invasive earthworms are the most prominent. European earthworms are the
> primary culprits in the northern forests, but Asian, African, and South
> American species have all found there way to North America.
>
> Collective nouns are not a problem in themselves, but it is troublesome
> when a collective term is applied to describe the homogeneity of something
> that is far from homogeneous. E.g., not all earthworm individuals are the
> same species and as such not all function the same; not all earthworm
> species are beneficial in all locations.
>
