AThomas,
Well, what is the end game? If some Gov't mandates that we will all feel good all over if we burn a "renewable" fuel, and generously passes out credits and the like, and mandates that X% of a power companies output will be via renew-ables, then it doesn't much matter where the trees come from or if it is actually carbon neutral. The end game is satisfying some Gov't mandate and reaping what is available from the credits, and, of course, making the do-gooders feel real good about themselves so that they will have more enthusiasm for driving their carbon not neutral cars to another "save the planet" rally.
The goal is met, the Gov't is satisfied, and the do-gooders can break their arms patting themselves on the back for having saved the planet.
Most of the biomass burning is just that type of hokum (or is it hokem?). Wood processing companies burned trees (or the remnants thereof after processing the wood) since time eternal because it was more cost effective to burn a waste product than have to land fill it and purchase other fuels for their power requirements.
A sugar mill Manager once told me not to make his process more efficient because it would result in excess bagasse (left over after grinding the cane to extract the sugar juice) that he would have to pay to have land-filled.
I could just as easily make the case that bio mass burning will never be carbon neutral, even if new trees are planted tree for tree or switch grass is replanted blade for blade.
The carbon burned by the equipment used to cut, harvest, and haul the biomass will never be recouped unless trees are planted on a 1:1+ ratio. Then you have to burn fuel to prepare the land for planting the extra trees/grass.
Nature has a way of regenerating itself, so the Canadian trees will probably grow back naturally, so Canada will be the beneficiary of England's do gooder gov't. I think it has been established that new growth trees absorb carbon out of the atmosphere much more rapidly than old growth trees, and if those trees died on the stump, the planet would die starting first in Canada.
If it were financially viable, no one would have to pay anyone to burn trees. The planet would be denuded of trees. The plain truth is that there are less costly fuels to burn, but some of them (think for example that dirty nasty "C" word - why, you can't even say that 4 letter word anymore can you?) are just too un PC.
Therefore, you have to have financial incentives to burn these "desirable" fuels to keep companies from having to burn the undesirables.
Let's all have a group hug. I feel so good about myself. I have burned many, many, many a ton of wood in the day. Why I may even be Al Gore class with respect to saving the planet. I can see a Nobel Peace Prize in it.
I hope somewhere in all the overstatement and hyperbole there was the answer to your question. I feel better now, really.
rmw