TOWARDS A PERMACULTURE LIVESTOCK ECONOMY - MEAT: A Benign Extravagance - page 317

is likely to perform better than bio-ethanol crops or rape for biodiesel. More remote pas-
ture will not get such high returns from industrial scale SRC because the land is less fertile,
more exposed and precipitous, and because inputs and outputs have to be transported fur-
ther. The best option for biomass on the rougher kind of pasture land, which is the land we
can most easily afford, is likely to be conventional semi-natural or plantation forestry.
However, in their enthusiasm for SRC, scientists and environmentalists drawing up car-
bon budgets tend to be snobbishly dismissive of the value of conventional woodland. It
may be a viable option for Scandinavia, they say, but in the UK there are too many people
and not enough trees. 10 The Royal Commission for Environmental Pollution (RCEP) states
that 'at best 3.1 million oven-dried tonnes of wood-derived fuel could be made available'
from Britain's 2.74 million hectares of woodland. 11 This equals about 3.75 million tonnes
of air-dried firewood - about 1.4 tonnes per hectare or from two to three cubic metres per
hectare, depending whether it is soft wood or hardwood. 12 This seems rather pessimist-
ic, even if we allow that some of the woodland is currently poorly managed, since typic-
al yields range from four to six cubic metres per hectare for oak to over 20 cubic metres
per hectare for some softwoods. 13 Estimates in other environmental reports vary consid-
erably with the highest being 13 million tonnes of oven dried wood available throughout
the country - more than four times as much as the RCEP estimate. 14 The RCEP is perhaps
discounting the wood used for the timber and pulp industries, but there is no reason not to
take this into account because it can nearly all be burnt when it comes to the end of its life
and this will become progressively easier to implement as restrictions on dumping timber
products in landfill come into effect.
The British Trust for Conservation Volunteers (BTCV) probably have more experience
of harvesting firewood than the scientists who draw up these documents. Their woodland
handbook tells us 'there is an old rule of thumb that an acre of woodland can produce a
cord of wood per year indefinitely'. 15 Cords are piles of firewood, which are a convenient
dimension for forestry workers (four foot, by four foot, by eight foot), but awkward for sci-
entists because they are in imperial measurements and full of airgaps. On top of that green
wood weighs more than air-dried wood, while hardwoods such as oak and ash weigh more
than conifers or fast growing broadleaves such as willow. Another complication is that fire-
wood figures tend to be given in tonnes, whereas timber production is usually measured by
volume.
A cord weighs from 1.3 to 2.5 tonnes if it is green, and perhaps one tonne air dried if it is
spruce, or 1.8 tonnes if it is oak. A cord per acre of mixed timber might therefore contain in
the region of 1.4 tonnes of air dried firewood, the equivalent of 3.5 tonnes per hectare. 16 To
allow for inefficiencies, I'm inclined to lower the yield to three tonnes per hectare. BTCV
also give figures for air dried firewood from long rotation coppice, ranging from 2.5 tonnes