Bill,
Most of our harvesting is thinning, removing about 40/50 tonnes/ha. We have a system called Yield Class. In case you have something different, I'll briefly explain it. If you use it over there...ignore!
A Yield Class is a measure of the increase in volume per hectare per year. So a YC16 Sitka is growing at the rate of 16 cubic metres a year. The usual wisdom is to thin out 70% of the YC per year. Thus 70% of 16 =11.2...multiply by the thinning cycle, say every 5 years, gives a thinning weight of 56 cubic metres to be removed every thinning. The same system also tells us when the ideal time is for clearfelling and replant, ie when the growth rate begins to fall. In practice, the threat of windblow usually dictates that we clear before that point is reached.
As for the clear fell areas..with the UK being relatively small and over-populated, practically every forest is in constant view. So the visual impact often restricts us to small areas. I have never done more than a 10 ha block, and the edges often have to be filtered and uneven. When replanting, there is now a legal obligation to include, I think, 15% broadleaves/open ground.
Well, my brain is tired now! And I've had 2 teeth filled today, and the drugs are wearing off..so...see you tomorrow.
Norman
