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That's not quite true, it takes a lot longer than 80 years for forests to stop sequestering CO2, even for fast growing species.
by quixoticelixer- 7y ago
That's not quite true, it takes a lot longer than 80 years for forests to stop sequestering CO2, even for fast growing species.
- ARandomerDude 7y agoI don't think that was the argument. OP was saying after maturity the scales tip to being net emitters.
- quixoticelixer- 7y agoThey don't really ever change to be net emmitters, and it takes a long time for them to stop absorbing carbon ( a few hundred years)
- benj111 7y agoDo you have a source? Because you're directly contradicting the article.
- aukust 7y agoAnecdotal evidence suggests to me that European spruce stores more CO2 than it sheds way over 80 years old as a spruce grows in mass significantly decades after reaching that age. However here is a study that tries to bring some light to carbon pools on over-mature 167-213 year-old trees: https://www.mdpi.com/1999-4907/9/7/435/pdf https://www.mdpi.com/1999-4907/9/7/435/pdf
- bryanlarsen 7y agoAnecdotal evidence tells me that spruce trees are really good at suppressing undergrowth due to their acidic needless so claiming a mature first is a net emitter makes sense to me. The trees may be growing, but nothing else is.
- quixoticelixer- 7y agoWardle, P. (1991). Vegetation of New Zealand. Cambridge: Cambridge University Press. If I have time tomorrow i'll find the page.
- benj111 7y agoIs it possible we're talking about different things? You talking about individual trees and the article talking about forests as a whole.
- quixoticelixer- 7y agoNo, if anything individual trees do start to become emitter as they age due to low growth and decay, how ever in forests old dying trees are quickly replaced by new ones.
- garmaine 7y agoYou don’t need a source. To be a net emitter the tree would have to be losing mass. That’s not what healthy trees do, even old ones. I believe the article might have been trying to say is that trees tend to die and decompose (or burn) which makes them carbon emitters.
- benj111 7y agoYou're talking about individual trees though. Theres plenty of mechanisms where the individual trees grow, but the forest holds less carbon. The linked article [1] mentions forest fires and insect infestations. [1] https://www.cbc.ca/news/canada/calgary/canada-forests-carbon-sink-or-source-1.5011490 https://www.cbc.ca/news/canada/calgary/canada-forests-carbon...
- jefftk 7y agoIf a tree keeps growing, but also gets more successful at suppressing growth of it's neighbors, then it can be a net emitter overall even though it's a net absorber considered individually.
- Robotbeat 7y agoThat’s not true. Methane is a significantly more potent greenhouse gas than CO2, so if the tree is absorbing CO2 but the decomposing needles and leaves are emitting methane, it could easily be a net GHG emitter.
- garmaine 7y agoTrees don’t produce CH4 (except in decomposition).
- lmilcin 7y ago"On average", no forest produces or consumes any CO2 or O2 unless the biomass is somehow sequestered, for example buried under volcanic ash or on the bottom of anoxic lake which would typically prevent it from decomposing. The forest binds some amount of carbon and oxygen for a time being but then it is released back when it burns or decomposes, etc. It is really insignificant when compared with steady flow of carbon from fossil fuels.
- bluGill 7y agoThat isn't completely true. A well managed forest will sequester some carbon when it burns. Note well managed in there, that means a small fire every year, a large fire gets hot enough to burn all the carbon, but a small fire will burn only part of the carbon and leave the rest as charcoal. Moral: shoot smokey the bear and let foresters start the fires they want to if only they were allowed to. Of course the above is a generalization, and as all of them false in some way. Ask your local forester what applies to the forest in your area, but don't try to apply it to a forest in the next neighborhood as that might be different.
- lmilcin 7y agoTo sequester carbon it would have to be prevented from decomposing. It is not enough for the trees to turn to charcoal during fire. If what you said was true "well managed" forest would be standing atop of layers of charcoal which obviously is not true. Instead what I suspect happens is that the charcoal from fires weathers, crumbles and becomes part of the soil. Soil is feed for other organisms.
- bluGill 7y agoThe charcoal is mixed in with soil, it is there.