4 ms·

Don't you leave out the thickening of trunks, and most importantly, carbon storage from fallen leaves of deciduous trees? Imho, the humus is also a compartment

Don't you leave out the thickening of trunks, and most importantly, carbon storage from fallen leaves of deciduous trees? Imho, the humus is also a compartment of the forest that stores carbon (even if it will be slowly transformed). Also, the decay of fallen trees is very slow, and is not 100% into carbon dioxide (the carbon will remain a very long time in the body of numerous plant and animal species), whereas the combustion for human use is complete and on a much smaller scale of time.

jandrese 6y ago
The problem is that fallen leaves tend to decay in fairly short order. The total carbon capture is basically the current leaves plus one or two years of fallen leaves and that's it. The rest have returned most of their carbon to the atmosphere. And when you think about it, this makes sense. Trees aren't constantly burying themselves in their own leaves. The roots of trees stay about the same depth year after year, and they're not growing new root systems higher up the trunk.
- njarboe 6y ago
  While I would guess that you are right for most trees, the Giant Sequoia redwood trees in California actually do bury themselves in their own pine needles. They can also grow roots out at a higher level, if needed. Of course they can live for thousands of years.
- henearkr 6y ago
  It doesn't have to stay in the form of leaves. Only a fraction (maybe not tiny) really goes back to CO2, but a lot turns into other organisms, raw fiber, etc. So you argument would be: why then do trees not bury themselves in humus? I think that a fair part goes away with rain and water systems, and a small portion circulates in the form of mobile organisms.
  - jandrese 6y ago
    Leaves may blow around some, but on most of the forest floor there isn't anywhere for them to go. Some of the leaves get eaten or turned into fungus or whatnot, but those die off too and eventually return to the air. There was a time in the Earth's history where this wasn't the case. During the carboniferous phase plant life didn't decay and biomatter piled up on the forest floor in miles-thick layers. The CO2 levels in the atmosphere dropped so low that the planet was verging on an iceball at times. The carbon balance was only maintained via enormous forest fires in the oxygen rich atmosphere.
- pvaldes 6y ago
  I think that we are missing the earthworms in this model. Carbon from leaves would be accumulated in invertebrate's bodies for a while... except by our burning soil addiction.
- henearkr 6y ago
  It's more like decades, not mere two years, for at least a fraction of the biomass in the humus. See my previous comment: https://news.ycombinator.com/item?id=26935290 https://news.ycombinator.com/item?id=26935290

jandrese 6y ago

The problem is that fallen leaves tend to decay in fairly short order. The total carbon capture is basically the current leaves plus one or two years of fallen leaves and that's it. The rest have returned most of their carbon to the atmosphere. And when you think about it, this makes sense. Trees aren't constantly burying themselves in their own leaves. The roots of trees stay about the same depth year after year, and they're not growing new root systems higher up the trunk.

njarboe 6y ago
While I would guess that you are right for most trees, the Giant Sequoia redwood trees in California actually do bury themselves in their own pine needles. They can also grow roots out at a higher level, if needed. Of course they can live for thousands of years.
henearkr 6y ago
It doesn't have to stay in the form of leaves. Only a fraction (maybe not tiny) really goes back to CO2, but a lot turns into other organisms, raw fiber, etc. So you argument would be: why then do trees not bury themselves in humus? I think that a fair part goes away with rain and water systems, and a small portion circulates in the form of mobile organisms.
- jandrese 6y ago
  Leaves may blow around some, but on most of the forest floor there isn't anywhere for them to go. Some of the leaves get eaten or turned into fungus or whatnot, but those die off too and eventually return to the air. There was a time in the Earth's history where this wasn't the case. During the carboniferous phase plant life didn't decay and biomatter piled up on the forest floor in miles-thick layers. The CO2 levels in the atmosphere dropped so low that the planet was verging on an iceball at times. The carbon balance was only maintained via enormous forest fires in the oxygen rich atmosphere.
pvaldes 6y ago
I think that we are missing the earthworms in this model. Carbon from leaves would be accumulated in invertebrate's bodies for a while... except by our burning soil addiction.
henearkr 6y ago
It's more like decades, not mere two years, for at least a fraction of the biomass in the humus. See my previous comment: https://news.ycombinator.com/item?id=26935290 https://news.ycombinator.com/item?id=26935290