all theory thread DESIGN PRINCIPLES used in our course not

permed at nor.com.au permed at nor.com.au
Sun Sep 3 17:45:27 EDT 2000


The weed debate, especially exotics vs natives is a complex issue with 
numerous layers of implications and considerations. I try to tread a 
delicate pathway between the factional extremes. 

As a pc teacher and designer I advocate the following basic guidelines

1. a high level of responsibility towards protecting the integrity of 
remnant ecosystems and surrounding these with a buffer of endemic 
(locally native) plants which can also be selected for yields and 
specific functions - i.e. productive native systems for fuel, fibre, 
fodder, bee forage, native foods, medicines, craft materials, timber etc

2. In damaged and denuded areas re-introduce local native species 
assemblies along riparian zones (gullies, water courses and flood plains) 
and steep slopes as conservation forests, wildlife habitat and corridor 
regeneration. 

3. Where a native plant will do the job give it preference to an exotic

4. No system should be purely exotic - In inner zones where exotic plants 
provide most of our food & product needs aim to incorporate at least 20% 
native plants (for yield, pest predator habitat, birds, wildlife & other 
functions)

5. All systems need management, maintenance and monitoring - if you 
discover an introduced species getting out of control, readily self 
sowing or being spread by birds then seriously consider removing it from 
the system and replacing with a less rampant plant.

6. Re- bush regeneration look carefully at what factors have changed 
(drainage patterns, nutrients etc) and select appropriate plants from a 
native (local) ecosystem with similar qualities. Ecology is a dynamic 
process, one factor changes and the whole ecosystem will change to adapt 
- work with the process - we can't stop the ecological clock. Sometimes 
we need to accept the inevitable evolution of new hybrid (mixed native 
and exotic) ecosystems in many situations where the impact of agriculture 
and human settlement is irreversible (the Holmgren principle)

I am in the process of removing several species of introduced plants here 
at Djanbung Gardens which are proving to be too successful in dispersing 
themselves, they are not incredibly productive or palatable plants (like 
icecream beans - they are incredibly productive but you can only handle 
eating so much) and I and the system certainly won't suffer from their 
disappearance. Some have done their 'job' (e.g.succession) and I look 
forward to replacing them with something more productive. 

Each plant needs to be carefully evaluated and assessed within the 
context of the whole system. The perennial pigeon peas I used as a 
leguminous shrub pioneer are successfully self seeding but I don't 
consider them a problem - wallabies (small kangaroos) love to eat the 
young seedlings and will assist in their control. The native parrots love 
the seed, but they digest the seed and don't disperse it like the hard 
seeds of berries and fruits that pass through their digestive tract, and 
pigeon pea are easy to remove and eliminate from the system.

On Jarlanbah (PC community I designed) there are by-laws for the 
landscape on house lots which include a clause requiring the lot owner to 
be responsible for removing any plant escaping from their lot onto 
neighbouring lots or the community land.

Ultimately it is a matter of basic responsibility and respect for our 
native vegetation and ecosystems and trying to find a balance between the 
exotics that contribute to our survival and the right to survival of our 
unique native systems and species.

While all species are ultimately native to planet earth we do need to 
commit ourselves to local species conservation if we are truly concerned 
about earthcare and ecological responsibility.

Robyn Francis

Permaculture Education
Djanbung Gardens
PO Box 379
Nimbin NSW 2480 




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