[Strawbale] Sustainability of wood heat.

[Sherwood Botsford]

Corwyn wrote:
>
> No, I am saying that if you are creating pollution, and you don't know 
> how, or how quickly, it is being rendered into non-pollution, that you 
> must assume it is just accumulating.  Thus the relevant metric is not 
> concentration but total produced.
>
We never act with full knowledge.  Wood heating is at least first order 
similar to an open fire.  Considering the number of forest fires that 
occur each year, if wood combustion produced non-degradable products, 
we'd be up to our ears in them.

Secondly, I have a good idea what chemicals are produced:  CO2, CO, 
water vapour, and an assortment of tars and alcohols,   CO has a fairly 
short residence time in the environment.  The others are food for 
various bacteria.  (General rule:  If there is a way to extract energy 
out of a chemical reaction, some bacteria does it for a living.)

One of the concepts in ecology is that of carrying capacity.  Put X 
amount of organic material into a water body: Bacteria and plankton 
gobble it up.  Put 2X in, and the bacteria use up oxygen too fast, there 
is no longer O2 available in the water, and the ecology shifts from 
being an aerobic one to being anerobic one.  The anerobes are not nearly 
as fast nor as complete as the aerobs, so now organic matter accumulates 
in the water.

Almost any material presented in large enough quantities to a given 
ecology will disrupt it. 

>
> But the 24" tree is adding 2.3 inches^2 time height where the 6" is 
> only adding 1.9 inches^2 times height.  So, using your numbers, the 
> 24" tree is an increase over the 6" tree, not a diminishing return.  
> More if you assume it is taller.
>
> But, that was not my point.  What you have shown is how much wood you 
> can take at its current production rate, but haven't shown how that 
> will or will not change that production rate.
>
Don't forget that typically there are 10 6" trees for every 1 24" tree.  
The 6" trees are only half the height.  But because there are so many of 
them, 6" trees are building biomass several times as fast as the 24" trees.
>> While the 1 /(average lifespan) is an oversimplification it's a lower 
>> bound.  I probably could harvest 2-3% of the tree biomass on a 
>> sustainable basis, but the closer I get to the total productivity, 
>> the more careful I have to be to not screw up how I take that mass 
>> out of the system.  Short rotation poplar farms can harvest a crop 
>> every 8 years.  But to do that, you have to grow it as a 
>> mono-culture, kill all the weeds under the canopy, and add 
>> supplemental fertilizer.  In the long run, I think this mines the soil.
>
> Seems to me like an upper bound, if you are removing 100% of the total 
> biomass increase.  The forest needs some percentage of that biomass to 
> survive.  Neither you, nor I, nor possibly anyone, knows what that 
> percentage is.  If you assume it is zero, I think you are dooming the 
> forest, in the same way that those who think it is negative are, just 
> slower.
>
What I was trying to point out was that the over simplification of 
1/(average lifespan) is a severe underestimate of the total 
productivity.  It ignores all the trees that died on the way to getting 
to that climax height.  It also ignores the trees that are non-usable 
for firewood, and the entire shrub/herbaceous plant/grass understory.




>
> Right.  You grow them bigger there.
>
>>> Tens cords is a lot.  I burn 2 for a 7500 Degree day climate.
>>>
>> Now I'm impressed.  Gives me incentive to put in more 
>> weatherstripping.  How many square feet is your house not including 
>> basement?
>
> Around 1600.
>
> And more than weatherstripping, insulation.
>
Our house is 2400 square feet.  1.5 times as much.  Our climate has a 
heat load 1.3 (10000/7500) times as much.
If I burned wood with equal efficiency to you, it would take me 4 cords. 
I build my stock to 10 cords. This year, with increased drying 
efficiency my wood consumption has dropped. It's mid February and I'm 
about half way through my 20' x 8' x 7' high loose jumble stack.  Looks 
like between 7 and 8. What should I be doing besides weather 
stripping/insulation to reduce my wood use?
>> True.  We do the best we can.  Keep on learning.  How do we define 
>> sustainable?  Forever?
>
> Forever.  Yes, please.  Ok, fine, 5 billion years.
>
Sorry.  Current understanding of stellar evolution will have the sun 
getting too warm in about another half billion years, and unless we take 
direct action in some form, the oceans will boil.  Gotta make 
sunshades,  or move the planet.
>>  Nothing is sustainable.
>
> Sure it is.  This planet had a positive energy balance for its first 
> 4.5 billion years.  Storing energy capital, even.  We are burning 
> through that capital at a rate of a million years accumulation per 
> year.  Unsustainable doesn't begin to describe it.  But if 'dumb 
> animals' (and dumb humans) could do it, smart humans should have no 
> trouble, right?
>
Planet has NOT had a positive energy balance throughout that time.  
There have been several glaciations that met at the equator, with only 
tiny pockets of open ocean near volcanic regions.  This is a long term 
stable state.  It required geological processes to break the hold of the 
ice. (Volcanoes release CO2, SOx which are both greenhouse gasses. 
Eventually enough built up to start thawing the oceans.) 

If you are defining sustainable as meaning some form of ecology will 
exist there, then you will find that almost anything is sustainable.  
Look at how rapidly Surtsey (volcanic island that popped out of the 
ocean near Iceland) was colonized by plants and critters. 

Trouble is that a definition of forever is not a useful criteria to 
decide between opposing viewpoints. Further, a replacement of one 
ecology with an entirely different one is not a definition of 
sustainable I agree with.

Could you give me a definition of sustainable that I can use to decide 
between two courses of action?

Clearly there are some things are non-sustainable. Usually we find out 
about these by their collapse.  The Atlantic cod Fishery. The west coast 
salmon fishery.  There are a bunch of other things that appear to be 
unsustainable because things we can measure are both finite and in 
decline.  E.g. soil depth on prairie farmland.  (A big reason for the 
zero-till/ reduced till systems that farmers and researchers are developing)

Productivity can be measured by net CO2 uptake.  It's hard to do.  You 
have to build towers high enough to sample the entire surface air 
turbulence zone, and measure CO2 levels continuously at several 
heights.  Or you have to take periodic samples and inventories.  By 
these measures,  spagnum peat bogs lead the way in net productivity.

The natural succession here is one of fire.  Aspen parkland cycles like 
this:
There is a forest fire, which clears the land.
Grass, and herbaceous plants come in.
Poplar, either aspen or black, come in depending on soil moisture levels.
When the poplar start falling from old age, the clearings are colonized 
by spruce. (Spruce seedlings are not viable without some shelter.)  The 
spruce forest grows up, gradually crowding out the poplar, and shading 
the understory to the point that the spruce is essentially a monoculture. 

Fire can reset it at any time, although black poplar once 30' high are 
immune to grass fire.
This is a simplification.  There are variations in terms of what shrubs 
come in depending on exposure.  We also have a few pockets where pine is 
the climax tree instead of spruce. (Drier, sandier soil)

If sustainable is define to mean positive net energy balance, then this 
is not sustainable.  It has a zero net energy balance.

It's also not sustainable by my definition:  There is too much change 
over the 2 century or so cycle time.  I have no  wish to have forest 
fires on my land.

So I deliberately take out the temporary excess biomass. 

Another way to judge sustainability is by comparison to a control zone.  
I will propose a test, as a thought experiment:
In my forest I will take 10 sets of 5 pictures of various parts of the 
forest.  I will take another 10 sets of 5 pictures in the forest down 
the creek on my neighbors land that has had no wood harvesting.  I 
submit all 20 sets to a third party.and ask them to pick the 10 sets 
that show the greatest biodiversity; pick the 10 sets that best show 
sustainable practice, pick the 10 sets that show the most interesting 
environment. 

If there is no apparent difference between the sets, then the land 
manager who claims sustainability is on track.  This would show up in 
that half the sets would be put in each category.  If the judge cited 
reasons for selection that depended on superficial characteristics, 
(existence of a stump, a trail) then the land manager could claim 
sustainable with minor impact.  If the judge cited differences in 
population: (No trees on the ground, obviously fewer trees per acre, or 
fewer large trees per acre, or fewer small trees per acre, then the 
manager may claim short term sustainable. If one look like a park or a 
dump, while the other looked normal, but all the species present in one 
appeared in the other, the manager could claim short term sustainable 
with major impact.

Another useful measure, although not one of sustainability, is 
biodiversity.  There are several ways to measure it:
There are several ways to measure biodiversity involving the number of 
species, relative populations, size of individual members.  One way to 
look at it:  Pick two critters, be they plant, bird, toadstool or 
bacteria.  What is the chance that they are members of the same species? 
The higher the probability, the lower the diversity.

These measures agree with the gut level instinct:  Aspen parkland has 
basically 4 species of trees: White spruce, paper birch, aspen and black 
poplar.  You find smaller patches of river birch, but they don't add 
much to the diversity, because they are rare.  You can make cases for 
willows and alder too.  Compare to the Eastern hardwood forests in 
Carolina. (As a kid my dad almost got a job there, so I started reading 
up on it.) An acre of woods there may have 150 different speices of 
trees and shrubs.  And another acre, a half mile away would also have 
150 species, but 50 of them would be different.  Much higher diversity.

In my fumble fingered way, I'm increasing the diversity.  I've planted 
sea buckthorn, chokecherry, lilac, crabapple, green ash that normally 
don't grow here.  I've dammed the local creek so there is a permanent 
body of water. (Not big enough for ducks, alas.)  When I harvest trees 
other than deadfall, I take them in patches, creating more edges.