NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/skeptic/22848

Text File | 1993-01-25 | 3.4 KB | 63 lines

Newsgroups: sci.skeptic
Path: sparky!uunet!pmafire!news.dell.com!natinst.com!cs.utexas.edu!hellgate.utah.edu!lanl!cochiti.lanl.gov!jlg
From: [e-mail] (J. Giles)
Subject: Re: does this sound right?
Message-ID: <[e-mail]>
Sender: [e-mail]
Organization: Los Alamos National Laboratory
References:  <1993Jan23.4286.31987@dosgate> <[e-mail]>
Distribution: sci
Date: Mon, 25 Jan 1993 22:29:02 GMT
Lines: 50

In article <[e-mail]>, [e-mail] (Robert McGrath) writes:
|> In article <1993Jan23.4286.31987@dosgate>, "dan mckinnon" <[e-mail]> writes in part:
|> |>    The "gone forever" part gives me more trouble, unless every acre is
|> |> on a mountainside and quickly devastated by erosion, or unless third
|> |> world countries are erecting shopping malls at an alarming rate.
|>
|> Got it on the second try (at least in the Amazon basin).  The soil
|> of the forest pretty much turns to useless muck in about two years
|> after the trees are cleared.  The forests do not grow back.  Nothing
|> much grows at all, especially if cattle are grazed on it.
|>
|> And in the case of ANY primary growth forest, clearing it out
|> is permanent. Even if a secondary growth forest develops (after
|> decades) it is NOT the same kind of forest, and much of the life
|> that lives there is gone forever.  Lots of trees is not the same
|> thing as a climax forest ecology.  Compare, for instance, the
|> unlogged forests of Oregon with the secondary growth in, say,
|> Michigan, which was logged out about 1910.

It's a little misleading to compare the Amazon basin to, say, Oregon.
In Oregon, many of the "old growth" forests are on the sites of recent
(less than a thousand years) complete devastation by volcanic activity.
Yes, the forests regrew.  The Amazon, on the other hand has not had a
history of widespread devastation and regrowth, so it's reasonable to
suppose that large-scale destruction *there* might indeed be permanent.

Comparing Michigan to Oregon has more sense.  There are still bound to
be differences in geology and climate, however.  And, only 90 years is
a little too short an interval (in forest terms) make any firm conclusions
about whether the Michigan forests can or will regrow.  There are also
questions about the effect of continued land-use and recreational
pressure on a forested area after cutting which can effect the rate
and quality of the regrowth.  Finally, it certainly makes a considerable
difference whether the logged area is replanted artificially or not
(artificially repopulated forests tend to be mono-cultures without
adequate diversity in the species and/or ages of the trees).

How much forest can be cut and what policies should be in place to best
encourage recovery and renewal of the resource are questions about which
a lot is known, but not nearly enough to make absolute positive claims.
The present state of knowledge leaves a lot of room for wildly different
opinions between equally well-informed scientists.  You could argue that
cutting down "old growth" forests before the above questions (and others)
have been answered is irresponsible.  On the other hand, depriving people
of an important source of income during a recession because of problems
that only *may* occur could also be characteized as irresponsible.  Welcome
to the wonderful world of politics.

--
J. Giles