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In a message dated 7/1/02 3:37:03 PM Eastern
Daylight Time, NJPharris@aol.com writes:
<< I can think of rainforests that do not show this physiognomy (and I'm sure Ben, as a Seattleite, can too...). Or maybe I'm missing the point. >> Unless you have a "a high-diversity tropical rainforest" in Seattle you are missing the point. DV Well, then so am I. I've just lend away my tree books, so
the following statement is subject to the vagarities of my memory, but my
recollections of walking through rainforests on the Australian East Coast - from
tropical ones in North Queensland to sub-tropical around Brisbane, and warm
temperate near Sydney, is that the major trees often don't show the classic
'jungle' physiognomies. In Mt Lammington National Park, for example (sub
tropical, near Brisbane), where I've spent many hours walking, the vegetation is
a patchwork of wet schlerophyll (dominated by eucalypt trees) and
rainforest-proper (still with lots of eucalypts, but also including others,
especially figs). The leaves on the rainforest growing eucalypts are
smooth edged (as are all gum leaves), but you wouldn't call them large, and as
for drip tips?
When you walk from a patch of wet schlerophyll
into rainforest, the feel of the forest changes. There is more shade, and
the temperature is much cooler. But I've always felt that it is the
composition of the understory, especially the large number of ferns (e.g. tree
ferns, Dickensonia) that is the most noticable difference between the
two physiognamies. You have to look real hard to see any differences in
the composition of the canopy.
Is this something unique to Australian rainforests, or is it
more generally true that the 'classic' rainforest look is not really
representative of the vegetation types that are termed rainforest? Are
there any botanists who can help out there?
Anyway, the notion of rainforests as diversity
hotspots seems to me to be a bit of a myth, especially if you are (as we all are
on this list) interested in larger creatures. Yes, they are full of lots
of different kinds of insects, and even though many of the plants look the same
there is an enormous diversity in them if you know what you're looking at.
And there can be a few birds (if you can see them). But as far as herps or
even mammals go? Give me a semi-arid zone or a river bank any day.
Even in rainforest zones the areas with most animals are
usually where (surprise, surprise) there is a high degree of structural
heterogeniety - patches of rainforests interspersed with dry woodland, open
grasslands, and swamps. Classic place to see this - national parks which
used to be logged, but are now protected. Lots of re-generating
vegetation, at different phases of growth. Lots and lots of birds and big
mammals.
Colin McHenry
56 Gaskill St CANOWINDRA, NSW 2804, Australia Ph: +61 2 6344 1009 Mobile phone: 0428 131 858 email: cmchenry@westserv.net.au
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