I've enjoyed the comments that have been left on my last several posts. They have made me think. I've responded to some on the post, but a couple needed more attention.
PioneerPreppy and CrazyLegobrothers both asked if space wasn't part of my sustainability problem. Can I be sustainable on 5 acres? If I can't then the outlook for the global population is truly grim. That is a question I'm still trying to answer.
So, to the PioneerPreppy, I've been working with a human range of about 20 square miles. I certainly don't need that much space devoted to feeding myself, but IF I can draw my resources from that area I know I can return them (I can walk 20 miles in a day...) and I know I will feel the impact of any mistake in 'management'. I've no science to back this up, just knowledge of how far I can travel, and how much land I can really get to know. Certainly more than one human can live in that range. How that works is a question for the future.
CrazyLegobrothers, I run into a problem with grain. The 4 of us use about 2 lbs of wheat per day as bread, pasta, crackers, etc. Where I live good conventional farmers produce a bit more than 50 bushels of wheat per acre. Organic produces come in at about 90% of that. Neither one is sustainable. Neither builds, or even maintains soil or fertility without importing lots of resources. (that doesn't even touch the energy required to produce and harvest monocrops on a large scale...) My family would need about 12 bushels of wheat (and some rice, oats, and corn) to continue living as we do. I suspect, due to inefficiencies of small scale production, weed pressure, etc, that I'd need about 1/2 acre of small grains each year. I could easily fit that into my 5 acres, but it would take my pasture production from being a soil building process to being a soil maintaining process. On a 5 year rotation (4 in perennial pasture, one in grain) I would lose all the humus I had built. Break even isn't a good plan for long term sustainability. No margin for bad years. I will get into more detail about this aspect of soil building in my next post. That doesn't account for the energy needs to till the field multiple times each year, manage the weeds, harvest, etc.
Wendy, I love the forest garden aspect of permaculture. There are a lot of great ideas and great potential in following a permaculture philosophy. But I haven't seen anyone in a temperate climate doing it without some big plowed field somewhere out on the fringes where they get their grain. You can't grow that much annual monocrop and be sustainable. As for the jungle being manipulated, I agree. Every creature manipulates their environment to enhance their own survival. Most do this passively, by eating selectively, spreading seeds, etc. Some, beavers for example, do this actively. It is all a kind of 'agriculture'. That is what gives me hope in my quest for a non-destructive method of food production and of living.