permaculture

[Toby Hemenway <toby@patternliteracy.com>]

(Pardon me for geeking out on this subject; I love these sorts of 
theory-meets-practice discussions; don’t really care about who is “right” or 
“wrong,” it’s more about getting the thinking done.)

Ossie at al.—

I totally agree that the fast-growing crap that is bred by timber companies 
is far less dense than old growth. No argument there. But I’m talking about 
real trees in real forests. Now, I’m sure there are plenty of data on rates 
of carbon sequestering under various conditions, and if my internet 
connection weren’t painfully slow these days, I would spend the time to look 
it up, but for now, I will use my experience as a geneticist, woodcutter, and 
botanist to guide my thinking.

I lived for 35 years in timber country and wonderful forests, and spent 20 
years as a geneticist. I’ve had fascinating discussions with timber company 
scientists, and they breed their trees just as Tyson breeds their chickens: 
to put on lots of low-quality material very fast, and then die at a young 
age. So you can’t compare the fluffy growth of those highly bred industrial 
trees with real trees. 

Having thought more about it (thanks, Ossie!), it’s not really about young 
versus old trees. It’s about light. It’s a simple matter of physics that 
trees that get more light, and thus more energy, will sequester more carbon 
than trees in a closed canopy.  If it were about age, there would have to be 
two different growth systems for the same tree, a low-sequestering phase 
during youth, and a high-sequestering phase at older age. And that’s 
unlikely. 

Given two trees of the same species, if one gets more light (and thus energy) 
than the other, it will sequester more carbon per year than one that gets 
less light. The growth rings will have similar density, but the high-light 
tree will have fatter growth rings and thus contain more carbon.   

This isn’t just theory, it’s been my experience. Having used wood heat for 15 
years, I have cut many trees, mostly young ones, of many species: lodgepole 
and ponderosa pine, Douglas and grand fir, Arbutus, walnut, oak, apple, 
cherry, alder, eucalyptus, and several others. The young trees contained very 
dense wood, no less dense than the wood in the old trees that I have cut. 
Wood that contained only fat growth rings was no lighter when dry than trees 
with thin rings. So it’s not about the age of the tree. Young, fast-grown 
wood of a “real” tree is pretty close in density to that of an older, slow 
growing tree. Perhaps a bit less dense, but I doubt if it’s significant. And 
if anyone made it through my earlier calculations of the area of growth rings 
at various tree diameters, you know that a thick, small-diameter ring can put 
down far more wood than a thin, large-diameter ring. So I’m still thinking 
that in general, fast-growing trees sequester more carbon than slow growing 
ones.

And what trees are fast-growing? Mostly young ones. In general, young trees 
have better access to light than older ones. It’s simple physics and 
statistics. Even old growth forests have light gaps due to storms, disease, 
insects, etc, and that’s where a lot of wood is being put on. Trees in gaps 
will grow fast. And then there’s fire and large scale blights that leave huge 
areas clear, giving great access to light for all trees over large acreages.

I know that this is where the fast growth occurs, because when I look at 
stumps and broken trees in almost any forest, natural or not, the pattern I 
see overwhelmingly is thick growth rings for the first 20-50 years, and thin 
growth rings after that, and I assume that this is because the light gap that 
allowed the trees to get started, whether it was large or small, closed after 
a few decades, slowing growth.

So although young trees have no mechanism that makes them sequester wood fast 
than old ones, young trees as a rule have better access to light, and thus 
are the trees doing the most to sequester carbon.

> Second thing that I would like to mention is that when trees "rot" in 
> forest they do not release all their carbon as CO2 into atmosphere as under 
> such conditions any CO2 released would be heavier than air and therefore 
> unless being technologically shot up into the sky would float under forest 
> canopy

I don’t think this is true. When wood rots, it’s not like it is producing 
dense clouds of heavy CO2 like dry ice (frozen CO2) sublimating into clouds 
of heavy vapor that sink to the earth. The CO2 is released slowly enough to 
be _dissolved_ into the air instantly. It goes into solution and is quickly 
carried away. An analogy: if you dump a cup of sugar into warm water, it just 
sinks to the bottom and stays there as a wet mass (that’s what dry ice is 
doing). If you sprinkle in a small spoonful at a time, it dissolves and 
disappears. That’s what rotting wood is doing. I read an abstract recently 
saying that forest CO2 levels were no higher than average. But it’s true that 
a fair amount of the CO2 released by rotting wood is taken up by nearby 
vegetation; that’s how the CO2 cycle works.

Thanks for the fun opportunity to exercise my brain on this.

Toby
tobyhemenway.com

Just out: my new book on urban permaculture, The Permaculture City. Order it 
at your favorite bookseller or get a signed copy from me at  
http://tobyhemenway.com/book/the-permaculture-city/


> On Jul 31, 2016, at 4:15 AM, ossi@kulma.net wrote:
> 
> Hi Toby et al.
> 
> Sorry to tell you, but it seems like you have not explored this issue 
> enough and I suggest you are wrong with the proposed assumption regarding 
> carbon storage in trees.   Such growth pattern you describe as universal 
> would apply only on trees grown in cleared open areas, f.e. after a 
> clearcut or as if timber is left in seed-tree positions after harvest.   
> Now if we compare to old growth forests this "universality" does not apply. 
>  As an example I have found more than 100 year old spruces grown from total 
> darkness of dense undergrowth so that they are only apx. 15 cm in diameter 
> but when dead seem to be more durable in use than most of the metals I know 
> about.  That kind of wood is heavy even if is totally dry.  In any of the 
> (semi)natural boreal forests I've seen that "universal" pattern you 
> describe doesn't apply unless it disturbed strongly by human intervention, 
> which equals to collapse in amount of stored carbon.
> 
> Rate of growth is very simple thing but big growth rings do not relate to 
> with how much carbon is stored in the tree.  You can have 3 times fatter 
> tree grown in 15 years, but when you  cut that tree down and dry it - it 
> can be lifted with single hand as there is not really carbon stored in 
> their cells, but rather empty space between relatively fragile cell walls 
> and their fresh weight was due to enormous amount of water that was there.  
> Due to large cell structures that kind of fast grown wood doesn't really 
> have any other use than to shade ground for natural forest to regenerate 
> with accumulated density, which stores the carbon for longest periods 
> available.
> 
> In contemporary Finland current construction wood sales are providing 
> mostly too low quality wood, so that they need to make composite elements 
> out of the wood-material available and therefore it is becoming rare to 
> find single timber being publicly sold as construction wood - as they do 
> not have much of such timber available due to unsustainable forest  
> management which was widely adopted since the 2nd world war.   I'd think 
> that old trees that grow slowly have just achieved their adulthood and 
> would likely store at least 1000 times more carbon both in dry weight and 
> durability in time than any fast grown crap from the pulp plantations.
> 
> So what comes to the forest management practice you describe, yes that is 
> useful in terms of fast supply for timber (which can be stored in buildings 
> for 500 years as you say), but do not relate that to optimal carbon storage 
> of trees as their capacity under such management is not even nearly the 
> optimum that can be achieved.  Also in terms of ecology leaving the oldest 
> trees growing should also apply especially if permaculture principles are 
> seriously taken under consideration.  I strongly suggest that maths 
> regarding such issues should follow logic like this: more density, more 
> carbon there will be stored and more durable that carbon is within extended 
> periods of time.  Of course there is somewhere a point where the growth 
> rate could be too little and cells get fragile due to that, but generally 
> in GOOD quality trees one likely cannot read the growth rings without 
> magnification as they are far less than 0,5 mm.
> 
> Second thing that I would like to mention is that when trees "rot" in 
> forest they do not release all their carbon as CO2 into atmosphere as under 
> such conditions any CO2 released would be heavier than air and therefore 
> unless being technologically shot up into the sky would float under forest 
> canopy and would be most of the year captured directly at least by conifers 
> or their lichen partners.   Also a lot of carbon that was in decomposed 
> wood especially in case of the old growth forest would be circulated by 
> fungi within the system and be either stored in soil or in community of 
> living beings.
> 
> Now, please keep up the good work you're doing.
> Thank you for you are and kind wishes for all sentient beings.
> 
> Ossi Kakko
> (Eastern Fennoscandia)
> 
> 
> 
> 
> Toby Hemenway wrote  2016-07-28 06:51:
>> Scott’s comments are excellent. I would add that the rate at which a
>> tree sequesters carbon is also dependent on where the other trees are
>> . Nearly all species of trees slow their growth rate enormously once
>> the canopy closes as they compete with other trees for light and
>> nutrients. I’ve looked at tree rings on many species of both hardwoods
>> and softwoods, and the pattern is universal: fast growth (fat growth
>> rings) for the first 20-60 years, then only slow growth after that.
>> They store most of their carbon in youth.
>> Solution would be to selectively log when the canopy closes to open up
>> light gaps so the other trees can keep growing fast. Then cut those
>> when they slow down, and plant new trees in the gaps. Put it all in
>> structures that last 500 years.
> 
>>> On Jul 27, 2016, at 5:53 PM, scott@permaculture.org wrote:
>>> In the case of fast maturing trees that are harvested at maturity would 
>>> be excellent building materials.  But trees that are still growing should 
>>> be allowed to continue to sequester carbon.
>>>> -------Original Message-------
>>>> From: Scott Vlaun <scott@moosepondarts.com>
>>>> To: permaculture <permaculture@lists.ibiblio.org>
>>>> Subject: Re: [permaculture] Earthships
>>>> Sent: Jul 27 '16 15:39
>>>> To Georg's point, sequestering carbon in well built structures made from 
>>>> wood harvested sustainably. Here in Maine there are short lived, fast 
>>>> growing species like balsam and poplar that make decent building 
>>>> materials and would otherwise die and quickly release carbon as they rot 
>>>> in the forest.
>>>> Scott Vlaun
>>>> Center for an Ecology-Based Economy 207 520 0575
>>>>> On Jul 27, 2016, at 5:33 PM, Scott Vlaun <scott@moosepondarts.com> wrote
>>>>> My mother in law lives in a 25 year old earthship in NM. I've spent a 
>>>>> lot of time in it and it is pretty fantastic. Can and bottle walls 
>>>>> eliminate a lot of carbon intensive concrete as do massive Adobe 
>>>>> thermal mass walls. The sculptural aspects, especially tile mosaic make 
>>>>> for a very Inspired living space. Embodied energy per sq. ft. on these 
>>>>> structures is extremely low and even in northern NM she gets by on less 
>>>>> than. Cord of wood per year, only needed when cold and cloudy. I'm 
>>>>> extremely sensitive to tire outgassing and have never even gotten a 
>>>>> whit. Labor intensive to be sure though!
>>>>> To
>>>>> Scott Vlaun
>>>>> Center for an Ecology-Based Economy 207 520 0575
>>>>>> On Jul 27, 2016, at 5:07 PM, Georg Parlow <g.parlow@gmx.at> wrote:
>>>>>> Thanks Lawrence and Scott for this dialogue. Valuable.
>>>>>> However, one question, Scott:
>>>>>>> **Whenever possible eliminate using forest products in construction.  
>>>>>>> The wood is much better used as a carbon sink.
>>>>>> To my understanding wood IS a carbon sink - and if it sits in my house 
>>>>>> for 200+ years this is just as fine as sitting (and maybe falling over 
>>>>>> and rotting) in the forest. What is it I do not see?
>>>>>> Georg
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