They practiced many forms of permaculture that had tremendous impacts on the natural environment, especially in their use of fire and other land management techniques to maximize the proliferation of useful plants and animals, all without plows, insecticides, herbicides, etc.
That's the culture and environment Europeans destroyed, not some "untamed wilderness."
True hunter-gatherer cultures are rare and have been for at least 60,000 years. Raw racism blinded European invaders preventing them from recognizing sophisticated and sustainable agricultural practices. This occurred throughout the world.
This sort of permaculture can't support the current human population of 8 billion people dependent on the science of the "green revolution" and fossil fuels for most of our food but it could guide our restoration of land that is currently farmed in unsustainable ways.
The true measure of nuts vs. cows is protein. What resources are required to produce a pound of nut protein vs. a pound of cow protein? What sort of "milk" that I pour on my breakfast cereal has the smallest environmental footprint? How many nut trees can California support in a sustainable way?
The reality of nuts like pistachios and almonds is that they were propagated for thousands of years by humans in environments very similar to California. There's nothing inherently wrong about growing these nuts but it has to be done in a sustainable way. Current practices are not sustainable.
The situation is even worse for California's dairy industry. This industry is watching the proliferation of vegan "milk" products and they are worried.
My wife and I are indirectly supported by the lettuce industry. This industry is likewise dependent on irrigation. Lettuce wouldn't be available in the grocery store all year round if it couldn't be grown on irrigated land in arid and semi-arid environments. Lettuce grown in fossil fueled hothouses for most of the year in places with abundant water would be a very expensive and resource-intensive delicacy.
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