I'm from Melbourne, Australia - cool temperate (usa equivalent zone 10)
I've finally got wood chips mulch which I'll use to prepare ground for my food forest.
However I would like to plant some screening plants first for privacy - hence can anyone please recommend what type of 'permaculture' tree that's suitable for a suburban & shady area?
The area would be under the shade of a big eucalyptus tree.
Ideally the height should be around 3 metre because our bedrooms are facing the street hence exposed to car's light at night but can be flexible
Thank you for your time & hope to hear from you soon!
Redhawk beat me to it....mature eucalypts are the bane of many a gardener. On my section, even the pasture composition changes and becomes far less diverse in the corner of the paddock under the big eucalypts. The trees are super efficient at pulling water from the soil, which is an adaptation to droughts common in Australian climates, and the leaf and bark litter is loaded with aromatic oils including phenols, which are toxic to many species. Best of all, they burn like petrol bombs, even when green. In some eucalyptus forests, almost nothing grows in the understory, including seedling trees, until a bush fire clears everything out.
We can observe the bare ground in the photo in proximity to the big tree. That is the problem you'll have to creatively work around...treat it as an opportunity.
I haven't got any food crops planted directly under eucalypts. I've got a couple big ones about 10-15m away from some hazelnut trees, and the closest ones are the first to suffer when we have a dry spell. Same goes for a mature chestnut at a similar distance from another large one...but it only gets stressed when we have a full-on drought. Olives, on the other hand, are a lot more tolerant of dry conditions and I have one about 5m away from a big swamp gum and it shows no ill effects.
Most of the allelopathic factors that I attribute to leaf and bark litter seem to primarily affect the growth of annuals under the trees, while the understory perennials that survive are the ones that handle low soil moisture. Lots of natives at our place do fine under the eucalypts as long as they're not shaded out. But they tend to be the tough ones. Even blackberries seem stunted when they try to get established (not that I do them any favours).
What about goji berries? They are hardy generalists, seem to like being crammed into hedgerows and fit into the shrub understory niche. They'd certainly provide a good screen from the street traffic.