Why One Tenth - or Nine Tenths - is Enough
If you use your land intensively you'll find that even if you only get a tenth of what the land provides, it'll be plenty - because one of the joys of the tithing system is that by living with other species your land becomes more productive - no pests, few weeds, incredible nutrient recycling and of course your life will be richer in other ways as well.
'Wild' fruit trees don't need fertilising, for example, because they feed on bird/ant/grasshopper etc dung and last time I looked at a hitherto sickly tangelo - planted in the wrong spot, neglected ever since and covered with scale for the past three years - it had no scale at all and had even turned green, instead of yellow. But now there's a giant red browed finch nest in it (they have communal nests - some become enormous. The birds eat the scale, feed the tree and forage other food that gets dropped from the nest to feed the tree as well.
I've never seen ANY system that couldn't be made more intensive. The acre around our place supports a handful of humans, 34 bower birds, 6 lyrebirds, 6 fulltime and three semi-transient wombats, three blacktailed wallabies, about 67 resident other birds, their offspring and many transients, 1 giant male roo (he was ousted from his position as leader of the mob last month and lives under the avocado trees now - it's a bit like having a retired President or Prince living on the property), innumerable bush rats and black rats, two sorts of mouse (haven't even tried to count them) - and I don't know how many other species as well. But every year it becomes more productive, more intensive and I reckon it'll get even more so every year for at least the next decade or two.
And in fact the ways you can 'intensify' production are probably infinite, once you break through the barriers that say you have to grow things in such and such a way. I've only just started to explore the potential of growing things up trees, mound gardens and the like.
Most Australian gardens are severely under planted - too much mown lawn, neat beds and unused space, and most of us have only small bits of land. If you want to grow enough for you, your friends and other species, and still not claim more than your fair share of space, you need to intensify its production.