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Probably the correct answer is: whatever rebuilds the soil. Forests represent the mature phase of an ecosystem, so jumping right into tree planting from barren

Probably the correct answer is: whatever rebuilds the soil. Forests represent the mature phase of an ecosystem, so jumping right into tree planting from barren field is likely not the best idea. You look at the edges of a road cut through a forest and you get an idea of the phases of regrowth for a forest. "Weeds", ie. smaller grasses and annuals, are the first pioneers. They then give way to bushes, and then later, trees, as the soil's capacity grows. There's still so much we don't know about living soil, but most of what we do know points to soil health being the key ingredient to healthy ecosystems. How much we can accelerate that through tree planting and what not is likely very dependent on local environment.

quixoticelixer- 6y ago
What do you mean by healthy soil?
- jehb 6y ago
  Generally soil health is measured by a number of things, from the easy to quantify like pH and percentage of organic matter and the availability of certain nutrients, or even simple physical measurements like depth, compaction, or water solubility, to more complex things like the makeup of the microbiota living within it. All of these things affect what and how well things can grow on top of it. I'm not a soil scientist, just an amateur gardener, but it's a very complex and interesting area of study.
  - hinkley 6y ago
    This is a chemist's answer. These are all proxies for "is there a healthy soil ecosystem?" Like a letter grade on your report card. Healthy soil has a ridiculously high number of individual microbes and invertebrates. When everything is going properly, soil carbon, pH, friability, gas/water permeability etc etc all work out to something forests like. Feed the soil, not the plant.
    - quixoticelixer- 6y ago
      Except that's not quite true, many forest soils are actually quite poor and the trees that grow there would grow much better in other, different soils. e.g many forest soils are much more acidic than ideal for tree growth.
      - hinkley 6y ago
        Fair. There's a tendency in my circles to talk about temperate forests (with fungally dominated soils) as if they're the most important. It's what we see, and it's what most 1st world people who need to hear about environmental policy see, and it's where the most space for improvement exists, both in terms of restoration and carbon sunk per acre. Tropical rainforests are something else entirely. In fungal soil, nutrient availability is a bit fuzzy, because if you're not in a symbiotic relationship with the soil fungi, or root fused to a sibling that is, you have a lot less access to minerals. Some people prefer to think of this as a benevolent relationship, but what's the line between exchange and extortion, especially when you can't ask either party how they feel about it? 'Codependent' might be the correct word. I don't know if he still feels this way, but Paul Stamets has on at least one occasion accused the fungi of farming the forest and not the other way around. If the fungi maintain a situation that is unfavorable to a particular tree, then they are not interested in having that tree around (whether that ultimately proves to be self-inflicted harm is sorted out by natural selection).
        jberryman 6y ago
        OT: but do you have any favorite books on ecology you can recommend to an interested lay-person?
        hinkley 6y ago
        I’m not much past 1000 hours myself, which is about when you can string together original thoughts that might be correct. I was always a fan of systems thinking so it’s been sucking me in. The matriarch of the family was the last master gardener as far as I’m aware, but I still have 15 years to match her and I think I might just... except she had a massive apple tree whose match I’ve seen maybe once, and I’ll be dead before any tree I plant is over 18”. Secret Life of Trees, Mycelium Running, and to a lesser extent Gaia’s Garden (by the late, great Toby Hemenway) all have different vignettes about solid ecology that created as many questions as they answered, but lacking a teacher that can be a good thing. I’m slowly filling those gaps in elsewhere.
  - quixoticelixer- 6y ago
    Except that lots of forests have terrible soil with low pH , low carbon, very low nutrient levels and are actually quite difficult for things to grow in.
- pvaldes 6y ago
  Healthy soil means soil with life. Fertile soil that takes 100 years to mature. After a wildfire only the mineral soil remains. Is sand and rocks basically. This soil can not store water at the same level.
hinkley 6y ago
The correct answer is a combination of that and accounting for the dynamics between tree species. Friend who does wetland restoration complained many times about how typical projects show up and plant 20 species all at once and walk away. Problem is, plants establish at different rates and conditions. They close canopy at different rates. They change soil biology in favor or against other species at different rates. In his ideal world, the 'planting' would be spread out over 4 years, where the slow plants get a head start. However, I'm not sure he's entirely right either. Because after 4 years, you'll have an area full of opportunistic plants if you don't do something to close the canopy fairly quickly. And if that's true, then there is no way to replant a forest except to spend 40 years doing it, forcing successions to get to your target species in 80 years instead of 200.
- hinkley 6y ago
  I say "no way", but it deserves a clarification. There is no way to do it at scale. There is forest succession, and there is secondary forest succession. If a hurricane, ice storm, 2 year drought, or the shock wave of a volcano wipes out all of the trees in an area, you get what is called a secondary succession. Much of the soil and all of the wood is still there, so a shorter path that goes from forest clearing to mature forest species can be taken instead. Logging destroys the process, and you go back to prairie, which is a longer route. If you're restoring an acre? You can ship in enough wood chips to approximate the food chain around a dead tree, kickstarting a secondary succession. It's a trick Permaculturists are using to build soil far faster than your science book says, but they only do it by diverting a waste stream from thousands of neighbors. You'd never find enough material to replant the forest between you and the next town. But you could build an island, and when that's done build another, and let them grow toward each other and toward the next town (who does the same) and you might have something better than a million hectares of doug fir in forty years, ready to burn down again.

quixoticelixer- 6y ago

What do you mean by healthy soil?

jehb 6y ago
Generally soil health is measured by a number of things, from the easy to quantify like pH and percentage of organic matter and the availability of certain nutrients, or even simple physical measurements like depth, compaction, or water solubility, to more complex things like the makeup of the microbiota living within it. All of these things affect what and how well things can grow on top of it. I'm not a soil scientist, just an amateur gardener, but it's a very complex and interesting area of study.
- hinkley 6y ago
  This is a chemist's answer. These are all proxies for "is there a healthy soil ecosystem?" Like a letter grade on your report card. Healthy soil has a ridiculously high number of individual microbes and invertebrates. When everything is going properly, soil carbon, pH, friability, gas/water permeability etc etc all work out to something forests like. Feed the soil, not the plant.
  - quixoticelixer- 6y ago
    Except that's not quite true, many forest soils are actually quite poor and the trees that grow there would grow much better in other, different soils. e.g many forest soils are much more acidic than ideal for tree growth.
    - hinkley 6y ago
      Fair. There's a tendency in my circles to talk about temperate forests (with fungally dominated soils) as if they're the most important. It's what we see, and it's what most 1st world people who need to hear about environmental policy see, and it's where the most space for improvement exists, both in terms of restoration and carbon sunk per acre. Tropical rainforests are something else entirely. In fungal soil, nutrient availability is a bit fuzzy, because if you're not in a symbiotic relationship with the soil fungi, or root fused to a sibling that is, you have a lot less access to minerals. Some people prefer to think of this as a benevolent relationship, but what's the line between exchange and extortion, especially when you can't ask either party how they feel about it? 'Codependent' might be the correct word. I don't know if he still feels this way, but Paul Stamets has on at least one occasion accused the fungi of farming the forest and not the other way around. If the fungi maintain a situation that is unfavorable to a particular tree, then they are not interested in having that tree around (whether that ultimately proves to be self-inflicted harm is sorted out by natural selection).
      - jberryman 6y ago
        OT: but do you have any favorite books on ecology you can recommend to an interested lay-person?
        hinkley 6y ago
        I’m not much past 1000 hours myself, which is about when you can string together original thoughts that might be correct. I was always a fan of systems thinking so it’s been sucking me in. The matriarch of the family was the last master gardener as far as I’m aware, but I still have 15 years to match her and I think I might just... except she had a massive apple tree whose match I’ve seen maybe once, and I’ll be dead before any tree I plant is over 18”. Secret Life of Trees, Mycelium Running, and to a lesser extent Gaia’s Garden (by the late, great Toby Hemenway) all have different vignettes about solid ecology that created as many questions as they answered, but lacking a teacher that can be a good thing. I’m slowly filling those gaps in elsewhere.
- quixoticelixer- 6y ago
  Except that lots of forests have terrible soil with low pH , low carbon, very low nutrient levels and are actually quite difficult for things to grow in.
pvaldes 6y ago
Healthy soil means soil with life. Fertile soil that takes 100 years to mature. After a wildfire only the mineral soil remains. Is sand and rocks basically. This soil can not store water at the same level.

hinkley 6y ago

The correct answer is a combination of that and accounting for the dynamics between tree species. Friend who does wetland restoration complained many times about how typical projects show up and plant 20 species all at once and walk away. Problem is, plants establish at different rates and conditions. They close canopy at different rates. They change soil biology in favor or against other species at different rates. In his ideal world, the 'planting' would be spread out over 4 years, where the slow plants get a head start. However, I'm not sure he's entirely right either. Because after 4 years, you'll have an area full of opportunistic plants if you don't do something to close the canopy fairly quickly. And if that's true, then there is no way to replant a forest except to spend 40 years doing it, forcing successions to get to your target species in 80 years instead of 200.

hinkley 6y ago
I say "no way", but it deserves a clarification. There is no way to do it at scale. There is forest succession, and there is secondary forest succession. If a hurricane, ice storm, 2 year drought, or the shock wave of a volcano wipes out all of the trees in an area, you get what is called a secondary succession. Much of the soil and all of the wood is still there, so a shorter path that goes from forest clearing to mature forest species can be taken instead. Logging destroys the process, and you go back to prairie, which is a longer route. If you're restoring an acre? You can ship in enough wood chips to approximate the food chain around a dead tree, kickstarting a secondary succession. It's a trick Permaculturists are using to build soil far faster than your science book says, but they only do it by diverting a waste stream from thousands of neighbors. You'd never find enough material to replant the forest between you and the next town. But you could build an island, and when that's done build another, and let them grow toward each other and toward the next town (who does the same) and you might have something better than a million hectares of doug fir in forty years, ready to burn down again.