Alien Invasive Vegetation

Regarding this discussion - the situation is South Africa is just as dire.
Our main problems are with Australian exotics gone wild ; mainly Acacia spp
& Hakeas with the Albizzia lophantha, some  Eucalypts & pines thrown in. I'm
a very keen hiker & its a shock to see how some of these aliens have taken
off into some of the most remote & pristine areas of fynbos.

One of the things to contemplate on the success of alien invasive species
though is that their success derives from their ability to utilise available
water resources for germination & more rapid growth than the indigenous
flora & therefore supersede it. The environmental sciences unit at the
University of Capetown did a lot of reseach on this & came up with some
quite impressive results as to what alien vegetation was doing to the
countrys water resources. I'm quite sure the principal here is applicable to
similar circumstances overseas as well.
Essentially, as alien cover increased it was taking up & transpiring more
groundwater than the indigenous vegetation & therefore allowing less to
reach the rivers & aquifers & so less was available for irrigation & urban
usage.
One of the real success stories of the incoming ANC government has been the
water affairs department which, rather than putting its money into new
reservoirs & dams, implemented the working for water project.Here the
unemployed are organised to eradicate aliens in all the catchment areas &
river reserves so only the original vegetation remains. River flows have
picked up again giving greater water reserves in the existing reservoirs &
springs have started flowing again which were formally dry.
And - as a real bonus - the existing flora is preserved.
Theres still a long way to go though & the extent of the problem is
staggering. They're also very aggressive with biological control
initiatives. - gall wasps for specific species etc.

I thought people might be interested that all the news isn't doom & gloom &
that somewhere there is still cause for optimism.

Regards

Glenn Breayley. Ragnarok & Valhalla Research.
POBox 26158, Hout Bay, 7872, Capetown, South Africa
Ph SA 021 7904253 Fax SA 021 7905139 E-mail valhalla@iafrica.com
Wholesale nurseryman & Tillandsia specialist wholesale & retail grower.
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