> Invasive species do far more harm to their biospheres than good.

I mentioned that there's a preference for native species. One of the principles taught is "the problem is the solution". If there are going to be invasive species or undesirable plants such as weeds anyways, why not use them? It's a pragmatic approach vs going to war with an animal or a plant.

> So when Permaculturists discount controlling those species they are failing to do the very thing they claim to be attempting to do: build healthy ecosystems.

I've heard criticism of using herbicides/pesticides to control the so called invasive species, where the intervention causes harm to the ecosystem. Rather than using pesticides, think of harnessing natural processes to benefit people & create a balance.

Again, it's the approach of going to war against a plant or animal. Anecdotally, I saw a grad student cheering to videos of divers spear fishing Lion Fish in the gulf & telling me that we need to eradicate the invasive Lion Fish from the Gulf. Did the spearing kill all of the Lion Fish? Did the problem go away?

In the West, we have this obsession with war & interventionalism and it carries over to natural ecosystems. Dumping chemicals in an attempt to eradicate an invasive species seems counter productive. Modern institutional science emphasizes measureables, while being blind to the broader context. The herbicides may achieve the measureable of reducing the observed biomass of a particular species, but at what cost? Is institutional science effective enough to imagine & measure all of the costs?

> I have seen Permaculturists become so obsessed with designing novel ecosystems that they even introduce invasive species.

I agree that could be a problem if done in a large scale. I was born on Maui, which had a mongoose introduced in a misguided countermeasure to snakes, which were not present in the islands when the Mongoose was introduced. Several natural Hawaiian song birds went extinct around that time. Others were reportedly hunted to extinction for their feathers to make the feather cloaks for the Ali'i. There have been escaped pets, like the Burmese Python in Florida, which multiply.

Even before people, invasive species were introduced into ecosystems with birds, migrating animals, the wind, etc. Somehow, the natural systems adjust.

Humans & global transport have accelerated this. Question is, do we spend our money & energy on intervening to create this utopia of what once was or do we adjust to the new circumstances & use our energy to create diverse natural ecosystems that benefit people? Is the pristine static set of ecosystems that we imagine a long term viable reality?

> But the methods and approaches taught by Permaculturists in PDC courses are deeply problematic.

The problem is the solution...as they say. Would it be better to have acres of lawns & sprawing centralized factory farms connected with a global shipping system, which spreads invasive species all over the world, setting aside small preserves for Nature? Or would it be better to regionalize & diversify food production using natural systems? People have to eat. Our current system of factory farming has done damage to billions of acres of land & watersheds. Before modern agriculture, civilizations, such as those who lives in the Amazon designed ecosystems that fed millions at the height of it's civilization. And we still benefit from their work via the Amazon Rain Forest, much of which grew from intentional ecological design with techniques such as building Terra Preta. I'm going to speculate that the people of the Amazons introduced invasive species during the process. Perhaps these principles can scale to green the deserts & feed the people of the region, as the OP demonstrates.