[Taxacom] Shorter trans-oceanic dispersal of Nothofagus

Geoffrey Read gread at actrix.gen.nz
Thu Jul 29 02:44:34 CDT 2010

>>> On 28/07/2010 at 5:51 p.m., Michael Heads  wrote:

>  [...] Some relevant facts are: Nothofagus grows down to sea-level in SW
> Zealand, and this area has one of the highest rainfalls in the world.
> Flooding, landslides, storms that break off large branches etc. happen
> all the time. And yet on Stewart Island (the third main island of New
> Zealand), just 25 km away across Foveaux Strait, Nothofagus is absent
> and probably never grew there (McGlone & Wilson, New Zealand J Botany
> 34: 369. 1996). The whole island comprises excellent Nothofagus habitat.
> If trans-oceanic dispersal is the key process, why has it not worked
> here?

Just to note that Foveaux Strait was dry for 10,000 yrs or so during the
glacial maximum, prior to the Holocene period considered by Wilson &
McGlone, so Nothofagus menziesii, if it could have survived the climate
then, could in theory have marched across the hills year by year onto
Stewart Island. No need for water voyages.  But it apparently didn't. Why
not? Climate likely wasn't suitable and it hadn't yet become present close
by on the mainland?


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