I posted a while back about the relative merits of grassland and woodland for food production. Here’s a little addendum to that post.
Suppose you can produce 170kg of beef from 1 hectare of grassland annually – quite a generous supposition, I think, if the cattle are being fed from the grass alone. That amounts to something like 1,960MJ of food energy.
Suppose alternatively that you have two oak trees and two crab apples on your hectare of woodland, producing something like 160kg of acorns and 100kg of crab apples annually. In practice, you’d probably have more than that, or at least you’d also have some other trees or shrubs producing something of food value, but frankly harvesting it all would be a pain so let’s take those figures as a realistic achievable harvest. That would yield something like 2,680MJ of food energy.
Now, I’m not saying that this crude exercise tells you anything very significant about whether you should choose woodland or grassland in any particular situation. And there are lots of additional factors to consider – other nutrients, processing inputs, fertility inputs and outputs, joint products, management issues, system redundancies, and palatability to name a few (a plate of roast beef or a plate of acorns – I know what I’d choose). Still, on the face of it this suggests to me that choosing to plant a woodland may not necessarily be inferior nutritionally to retaining permanent pasture, which is interesting.
In my earlier post I hedged my bets a bit, but I suppose my general drift assumed that a mature woodland was of less food value than permanent grassland. But now I’m not so sure that this is necessarily the case. Well, that’s the beauty of a blog, I suppose. Yesterday’s thoughts disappear off the bottom of the page, and are easily replaced with today’s entirely different ones. And nobody will notice and give me any grief about it, with the possible exception of Paul Hillman. But I don’t expect he’s looking.