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> ... forests (which when young are actually carbon emitters). Can you expand a bit on that, since it doesn't match my understanding? Where does the carbon com

> ... forests (which when young are actually carbon emitters). Can you expand a bit on that, since it doesn't match my understanding? Where does the carbon come from that young forests emit? My understanding is: A tree is a carbon sink, i.e. it captures carbon as long as it is growing (the carbon goes into its organic matter). Once it stops growing it has a constant amount of organic matter, a constant amount of carbon, and no net exchange of carbon. That is until it burns, or decomposes, or parts of it are eaten by animals, or whatever. The same, but on a larger scale, goes for a forest, or any ecosystem really: when total organic matter increases carbon is captured from the atmosphere; when total organic matter decreases carbon is emitted. Still to my understanding, young forests are forests that grow pretty rapidly and are therefore excellent in capturing carbon. What am I missing?

renlo 4y ago
Not OP but planting a man-made forest is bound to require a lot of carbon up front; you’d need to transport people, plants, etc, to the forest-site, and would possibly need prepare the land for planting using machines (which again need to be transported, need logistics to transport fuel, etc)
- oblak 4y ago
  I am not sure about the "a lot of carbon up front" part. Compared to the industrial, man made carbon capture plants madness, the cost of transporting young trees, people and water would be nothing. The main "problem" with the forests approach is that some very important people won't be making huge money off of it.
borkt 4y ago
A whole lot unfortunately, as the life is not a simple topic. https://pubmed.ncbi.nlm.nih.gov/34542151/#&gid=article-figures&pid=figure-1-uid-0 https://pubmed.ncbi.nlm.nih.gov/34542151/#&gid=article-figur...
- roelschroeven 4y ago
  How does that support the claim that young growing trees release more CO2 than they capture?
godelski 4y ago
Sure! I'm actually glad you asked, because this is a perfect example of first order thinking giving you the wrong answer. Your understanding is actually (almost) entirely correct! The problem is that a forest is an entire system, and not just the trees. Talk about missing the forest for the trees :) So a singular tree grows more aggressively when young, but you also have to consider that the tree respires and that it drops matter to the ground which microbes decompose and respire CO2! But the overall system changes once a forests get larger and there is canopy closure. Once we consider the entire system (or at least more of the system) we reverse our conclusion and find that young forests are NET carbon sources (despite individual trees being carbon sinks) and that old growth forests are NET carbon sinks. PBS Terra does a good explanation of it so I'm linking it here[0]. Also, with that said, we should add some information about land management. After all, logging cycles and maintaining old growth forests is part of land management, but it is far from the whole picture. Forrest Fleisch (ironic name) frequently writes about this so I'll just leave one post here[1] and allow you to dig in more. I hope this clears things up. I'm not an expert so I don't have all the answers myself. But this is what I've gathered from conservationists and those studying forests. And in all fairness, the prevailing theory was that of the first order until relatively recently when we could actually measure the entire system. So old information can be holding us back, but also I think this demonstrates that we as the public understanding can significantly lag that of the scientific consensus. While I agree we should challenge experts this also demonstrates the importance of relying on them. [0] https://www.youtube.com/watch?v=LDdKOmvIKyg https://www.youtube.com/watch?v=LDdKOmvIKyg [1] https://mobile.twitter.com/ForrestFleisch1/status/1306221445933129728 https://mobile.twitter.com/ForrestFleisch1/status/1306221445...
- roelschroeven 4y ago
  That twitter link talks about other complex effects, so let's focus on the PBS video. I'll have to find out more about the research, but just from the video things don't make sense. If a young forest is a net carbon source, they question remains: where does that carbon come from? Was there carbon stored in the soil that is released? If not, the carbon balance doesn't make any sense. As with anything, change in mass over time equals flow rate in minus flow rate out. If biomass increases, stored carbon increases as well, so flow rate in is larger than flow rate out. That means we have a carbon sink. I don't understand the research results for mature forests either. How can they be a carbon sink when the amount of biomass is constant? Something doesn't add up. It could be my understanding of things. I'm going to try and find some time to delve deeper in the research. Edit: it looks like the video mainly talks about disturbed forests, where trees are planted again to regrow the forest. It's not explicitly mentioned though, just silently assumed, and that creates lots of unnecessary confusion and misunderstanding. A disturbed forest likely still has relatively large amounts of biomass in the soil, that get released. That is not what I call a young forest though, which is what we were talking about here. A young forest doesn't have a lot of pre-existing biomass.

renlo 4y ago

Not OP but planting a man-made forest is bound to require a lot of carbon up front; you’d need to transport people, plants, etc, to the forest-site, and would possibly need prepare the land for planting using machines (which again need to be transported, need logistics to transport fuel, etc)

oblak 4y ago
I am not sure about the "a lot of carbon up front" part. Compared to the industrial, man made carbon capture plants madness, the cost of transporting young trees, people and water would be nothing. The main "problem" with the forests approach is that some very important people won't be making huge money off of it.

borkt 4y ago

A whole lot unfortunately, as the life is not a simple topic. https://pubmed.ncbi.nlm.nih.gov/34542151/#&gid=article-figures&pid=figure-1-uid-0 https://pubmed.ncbi.nlm.nih.gov/34542151/#&gid=article-figur...

roelschroeven 4y ago
How does that support the claim that young growing trees release more CO2 than they capture?

godelski 4y ago

Sure! I'm actually glad you asked, because this is a perfect example of first order thinking giving you the wrong answer. Your understanding is actually (almost) entirely correct! The problem is that a forest is an entire system, and not just the trees. Talk about missing the forest for the trees :) So a singular tree grows more aggressively when young, but you also have to consider that the tree respires and that it drops matter to the ground which microbes decompose and respire CO2! But the overall system changes once a forests get larger and there is canopy closure. Once we consider the entire system (or at least more of the system) we reverse our conclusion and find that young forests are NET carbon sources (despite individual trees being carbon sinks) and that old growth forests are NET carbon sinks. PBS Terra does a good explanation of it so I'm linking it here[0]. Also, with that said, we should add some information about land management. After all, logging cycles and maintaining old growth forests is part of land management, but it is far from the whole picture. Forrest Fleisch (ironic name) frequently writes about this so I'll just leave one post here[1] and allow you to dig in more. I hope this clears things up. I'm not an expert so I don't have all the answers myself. But this is what I've gathered from conservationists and those studying forests. And in all fairness, the prevailing theory was that of the first order until relatively recently when we could actually measure the entire system. So old information can be holding us back, but also I think this demonstrates that we as the public understanding can significantly lag that of the scientific consensus. While I agree we should challenge experts this also demonstrates the importance of relying on them. [0] https://www.youtube.com/watch?v=LDdKOmvIKyg https://www.youtube.com/watch?v=LDdKOmvIKyg [1] https://mobile.twitter.com/ForrestFleisch1/status/1306221445933129728 https://mobile.twitter.com/ForrestFleisch1/status/1306221445...

roelschroeven 4y ago
That twitter link talks about other complex effects, so let's focus on the PBS video. I'll have to find out more about the research, but just from the video things don't make sense. If a young forest is a net carbon source, they question remains: where does that carbon come from? Was there carbon stored in the soil that is released? If not, the carbon balance doesn't make any sense. As with anything, change in mass over time equals flow rate in minus flow rate out. If biomass increases, stored carbon increases as well, so flow rate in is larger than flow rate out. That means we have a carbon sink. I don't understand the research results for mature forests either. How can they be a carbon sink when the amount of biomass is constant? Something doesn't add up. It could be my understanding of things. I'm going to try and find some time to delve deeper in the research. Edit: it looks like the video mainly talks about disturbed forests, where trees are planted again to regrow the forest. It's not explicitly mentioned though, just silently assumed, and that creates lots of unnecessary confusion and misunderstanding. A disturbed forest likely still has relatively large amounts of biomass in the soil, that get released. That is not what I call a young forest though, which is what we were talking about here. A young forest doesn't have a lot of pre-existing biomass.