older trees grow faster, take up more carbon

Keep in mind that "growth" here is estimated aboveground gross biomass increment. Definitely a worthwhile study, which essentially involved the use of forest inventory statistics rather than new observations on trees. So, growth as used here does not include any deduction for decay on the inside or analysis of growth or productivity per unit area.
I had a good exchange with N. Stephenson, the primary author of the original paper in Nature, back in January. As so often the case, I have no quibble with the original research, but the newsy comic-book versions can be misleading! If anyone is interested in that conversation, please drop me a line.
 
A large tree would put on more growth as a whole in contrast to a smaller younger tree because of the overall volume, right? That does not mean that it grows more quickly than a a younger tree correct? I mean wouldn't you look at the terminal bud scale scars to determine how much growth is being put on yearly? I'm no expert, very interested though.
 
Exactly, Sean. A lot more wood is added to a large tree than for a small tree for a given ring width. For most regular folks, tree growth (at least for a small tree) is height growth. For aborists and mature trees, maybe growth means circumference or crown extent. For this study, growth was estimated as the amount of aboveground mass added without a correction factor for the amount lost due to decay. I'd like growth to mean the net total added above- and belowground per unit land area, after subtracting for shedding and decay. Much harder to get at. As usual, once the terms are defined, the number of arguments falls away.
But that difference between "net" and "gross" was what provoked a quick email to the author from me the night that the Nature publication embargo was lifted. After I got those definitions, I didn't have much of a squawk, except for the headline of the original article in Nature.
 
I think of it as a new layer being built around the tree on an annual basis. Each layer will require more Carbon as the building block to fully cover the structure. The larger the tree, the more C will be sequestered.
KTSmith, how important is it to look at a singular tree vs. the forest as a whole? I would think it vital to see the larger picture, since the net sequestration of the tree doesn't really account for where else in the forest the "lost" Carbon went. Does that make sense?

I think this thread will somehow resonate...the 2 dimensional part. I really miss Bob and his posts.
http://www.treebuzz.com/forum/threads/trees-as-pipes-wulkowicz-tune-in-please.23325/
 
Quite a bit of carbon held in the duff/detritus layer on the forest floor. While decay can be simply interpreted to release carbon I believe it is a very slow burn in a mature healthy forest, for example fungi and other organisms involved in decay processing are converting detritus into material available for plant and organism uptake. Maybe someone who understands this part of the woods ecosystem can shed some light on how carbon fits in, is it recycled back in to living plants through the decay process? A biologist friend mentioned something to me about significant carbon releases from the forest floor during large scale logging operations, this hints at some sort of dynamic (or static) sequestration happening in the duff/detritus layer.
 
Oceans: you rightly bring up the notion of scale, and that depends on the research question. The Nature paper that underlies this thread was speaking indvidual trees, in aggregate. Carbon cycling as an ecosystem process is in units of cabon per land area per uni of time, like tons per acre per year or moles per hectare per day.
Moss: sure, fngi and bacteria are breaking down organic (carbon-containing) compounds all the time, before and after digestion by bugs and a host of animals. The pathway from healthy tree to shed wood and foliage to breakdown by fungi and associates and back into the tree is through the respiration of organic comounds back into carbon dioxide which is then available for uptake through photosynthesis and biosynthesis of new organic compounds leading to wood, etc.
Carbon leaves the biome as respired CO2 and enters the biome as fixed CO2 via photosynthesis. In most temperate zone forests, as Moss points out, most of the stored carbon is in the humus of the forest floor. And most of that humus is fomed directly or indirectly through the action of wood decay fungi, especally brown rot.
The C releases during logging are well known. That release is by microbial aerobic respiration. Much of the release is from increased microbial metaboilsm simply from soil heating. This heating as well as the mechanical disturbance also causes a pulse of nitrogen fixation by bacteria, which is also fueled by respiraton of organic matter an release of CO2 into the atmosphere.
There is a lot that is not well understood about carbon cycling in forests, but the sketch above has been well-established for decades.
 
KTSmith said:
Keep in mind that "growth" here is estimated aboveground gross biomass increment. Definitely a worthwhile study, which essentially involved the use of forest inventory statistics rather than new observations on trees. So, growth as used here does not include any deduction for decay on the inside or analysis of growth or productivity per unit area.
I had a good exchange with N. Stephenson, the primary author of the original paper in Nature, back in January. As so often the case, I have no quibble with the original research, but the newsy comic-book versions can be misleading! If anyone is interested in that conversation, please drop me a line.
Click to expand...


Some is calculated by increment boring and ascertaining growth ring sizes back a number of centuries. Ascertaining and boring is not estimating as much as it is calculating. Let me put it differently ... maybe the one study did not use increment boring, but the study in the redwoods and other, did use it, and the conclusion is similar.

Decay material happens to both young or old trees. But decay material also has carbon in it ... a rotted log has stored carbon.

Regarding the article anyway, if an older bigger tree has a fairly complete wrap of cambium around it's trunk, the fact should be fairly consistent that it puts on more wood growth per year than a young tree, regardless of various decay pockets, if it even has any.
 
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I'm really seeing how the headline was off target, but trees growing "faster" probably sells more articles than trees growing "more". At least the article went out and established the grounds for discussion here.
 
Interesting to note that in some very favorable sites, mature trees still put on impressive vertical growth per year. Tall tree measurers call these locations "Super Sites". They're typically "cove" habitat in hilly or mountainous forested terrain, featuring good soil deposition low on the cove, good groundwater pressure and wind shelter. The "Jake Swamp Tree" white pine in the northern Berkshires, Massachusetts, is now 172', putting on roughly a foot in height per year, is in a super site. The plus 190' tuliptree in the Smokies is also in cove habitat. These trees are exemplary examples of their species and are no slouches as far as annual growth is concerned. I think the myth of "over-mature" forest trees is indeed a myth. -AJ
 
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