permaculture

["Naomi Rea" <Naomi.Rea@terc.csiro.au>]

ditto to message from Santa Cruz and G'day from Australia

The concept of highly productive, concentrated, low energy PC systems 
(food bowls) is admirable and attainable. However, the SCruz message 
a timely reminder about bumping up diversity with introduced 
non-native species.  Invasives are changing the floristic identity of 
ecosystems and countries.  Horticulture and spp introductions have 
alot to answer for.  Of 463 exotic pastures introducted to Northern 
Australia, only 5% had a potential use, 13% became weeds and < 1% 
were both useful and not weeds (Lonsdale 1994 Aust J. Ecol). 

Native plants have taken squillions of years to evolve superb 
adaptations and strategies. Can humans really hope to do better ?
Concepts such as ecosystem mimicry, landscape engineering and 
PC are laudable ideas for a planet facing food shortages, massive 
ecological change, rehabilitation of degraded environments and  and 
in need of a new social ethic ... but, am wondering if PC really is 
low energy ?  The native garden with bush foods, medicine, materials 
and fuel would have to be the ultimate low energy system.  Albeit, a 
PC-bush garden may not be as productive as a PC-everything system, 
but it is ecologically safe and long term.  Listening, looking and 
learning from natural systems, refined over centuries, may be easier 
than struggling to do better

Naomi


> Ref;  Potential  Invasiveness 
> 
> During a recent trip to Southwest China  we were traveling with a group of
> Chinese botantists -the subject of non-native plants came up into the
> conversation, -in that area apart from the ubiquitous ecalyptus plantations
> there were surprizingly few introduced plants in the landscape.   To our
> surprize the story of an invasive non-native Eupytorium sp. originally from
> Central America, and how it has been estimated to have invaded fully 30% of
> the tillable land in sub-tropical China. This particular weed is so toxic
> that even goats won't touch it!  And more labor is spent each year in
> trying to eradicate Eupytorium than in re-forrestation efforts.
> 
> We all have corollaries to the Eupatorium in South China, invasive plants
> that have escaped horticultural boundaries into our landscape and are
> creating havoc with farming.  Basically the problem appears that as
> bio-diversity is changed through introduction of non-native species the
> potential that some percentage of the introduced horticultural plants
> become naturalized and begin to expand their foothold.
> 
> Regions with mild climates seem the most at risk to non-native species, 
> and recently regional environmental planners have begun to site the
> problems of maintaining natural plant communities into the future. Also
> habitat destruction by invading species makes it necessary to enter fragile
> areas to try to separate and eradicate non-native plants.  The fact that
> the  invasive issue has not taken center stage is that many of the species
> are or were originally interesting horticultural species. Here in Central
> Coastal California the list of non-native invasive species now outnumbers
> the native forest and grassland species! 
> 
> The subject is further complicated when we consider the invasive potential
> of non-native fungus spore.  Phytothera genus fungus spore are a huge
> problem in nursery soils. Now escaped this non-native spore has destroyed
> the magnificent Chamycyparis lawsontonia (Port Orford Cedars) and on the
> East Coast the fungus Discula destructiva, threatens the  Cornus florida,
> eastern dogwoods.  These invasions were driven by horticultural plantings
> of non native species and we as plant lovers should  be aware that this
> whole historical example which is playing out in our own forests has
> occured before, European native forests were harvested and depleated by
> fungal blight before Elizabeth I, sent Raleigh to the new world in search
> of new and different plant species to "renew the forests".
> 
> Perhaps as we expand our own collections of rare and different plants we
> should be aware of the incredibly complicated and slow moving process that
> we are setting into motion.  Planting trees and bamboo increases the
> intellectual interaction between ourselves and the natural world but to
> begin to recreate the complexity of healthy environments we need to see
> beyond the quick returns of  agro-forestry; towards ways to stabilize
> healthy forests with natural diversity.  
> 
> There is a direction in the permaculture and new horticulture movements
> recently.  The ideal of planting a tree or bamboo that grows fast enough so
> that we can not only enjoy it's shade but harvest its wood for "expanded
> productivity". The idea that we can introduce fast growing "productive"
> species must be balanced by the potential that some of these species in
> some regions WILL produce unwanted results, as their aggressive traits
> escape beyond intended boundaries.
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