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This is somewhat of a misleading headline. Yes, the rate of deforestation may have peaked in 1980s. There is also not very good data on this before 1990s. The e

This is somewhat of a misleading headline. Yes, the rate of deforestation may have peaked in 1980s. There is also not very good data on this before 1990s. The estimate of forested areas in the context of our land use distribution are still in decline. Now this is adjacent but whats more important in my mind is not reflected in any of these data; that is to say that most of the planet's savanna have been completely lost. Savanna are arguably more important than forest due to the sequestration of carbon in-ground systems (as opposed to woody biomass) and the amount of caloric availability they offer to wild animals. They thus support a huge amount of biomass (though not necessarily biofuel, like a forest). Some of the areas that are being afforested originally would have been savannas but due to biodiversity loss, they succeed directly to forests (no animals to control the spread of trees). By some estimates less than 1% of North American oak savanna still exists today.

Robotbeat 5y ago
Is the savanah really an effective carbon sink, or is this still based on the (recently discredited) humus theory of soil?
- thatcat 5y ago
  Humus stabilizing in soil is the result of mycorhizzae extracting mineral elements from the soil and exchanging that for carbohydrates. The humus theory was that humus is an essential nutrient. If humus theory were true carbon would be removed, not added to soil. That theory was debunked more than 20 y ago. https://blog.nutri-tech.com.au/mycorrhizal-magic-new-biological-breakthrough/ https://blog.nutri-tech.com.au/mycorrhizal-magic-new-biologi...
- jnmandal 5y ago
  Not related. The suspected importance of savanna is more based on biodiversity than soil science. In these biomes, you have comparatively large amounts of animal and insect biomass. You have animals constantly eating the plants. This causes deep rooted plants which can regenerate quickly to dominate as they grow back intermittently. The sequestered carbon is mostly in the plants and animals as opposed to soil. Measuring biomass accumulation below ground is more difficult than above ground (counting trees is pretty easy). However some land use pattern studies have looked at which areas have historically been savanna normally show overlap with heavy agriculture regions as the soil is so good. In some cases these former oak savannas in the US will have dozens of feet of fertile topsoil. So there's some speculation that the high soil fertility in such biomes is due to compaction from grazing animals, which I guess is not related to the humus theory, but would be a similar idea about how so much carbon can accumulate.
mrjangles 5y ago
I found a great little link that compares deforestation / reforestation over time for different countries sorted by things like GDP. https://ourworldindata.org/forests-and-deforestation https://ourworldindata.org/forests-and-deforestation As you can see, most wealthy countries have been increasing their forest cover since 1990 (and indeed since the late 1970's though this graph doesn't go back that far). As poorer countries increase their industrial base and means of wealth production, they too will be able to afford to take care of their environments as well as a the West does.
- jnmandal 5y ago
  Yes, this is exactly what I was talking about. In the US for example, almost all of our historical savanna has been replaced by forests. The upper midwest used to be mostly oak savana biome but since the advent of afforestation those areas, mostly regrow as forest. This shift seems most related to eradication of native species which were able to maintain a system at certain level of ecological succession. So maybe without wolves, bison, passenger pigeons, (maybe even mastodon) these ecosystems aren't able to regrow and we instead get a much less biodiverse forest. There is some suspicion this has been the case for several hundred years as oral history from native American tribes suggests they at one time overhunted these resources and afterwards took an active hand in managing some of these ecosystems. However since the native Americans never cleared these areas they may have been in a better position to maintain them (mostly via controlled fires) whereas modern Americans are often starting with farm fields. Anyways yes, afforestation is happening at good clip but much of it is plantation and a lot of the afforested areas were never previously forest. The same is true in other countries from what I have seen. Even India has massive afforestation but most is agroforestry. A lot still remains to be seen. It's possible that these forests don't make sense as carbon sinks. Savana systems for local agriculture could be more efficient at mitigating carbon emissions. Nearly a third of land is now used for grazing worldwide and much of the output is shipped internationally. Like many other systems in nature and otherwise, it's very complex. So I'm not so sure the 90's era practice of reducing deforestation to simple arithmetic is constructive in an era where scientific community is pushing to maximize carbon sinks.

Robotbeat 5y ago

Is the savanah really an effective carbon sink, or is this still based on the (recently discredited) humus theory of soil?

thatcat 5y ago
Humus stabilizing in soil is the result of mycorhizzae extracting mineral elements from the soil and exchanging that for carbohydrates. The humus theory was that humus is an essential nutrient. If humus theory were true carbon would be removed, not added to soil. That theory was debunked more than 20 y ago. https://blog.nutri-tech.com.au/mycorrhizal-magic-new-biological-breakthrough/ https://blog.nutri-tech.com.au/mycorrhizal-magic-new-biologi...
jnmandal 5y ago
Not related. The suspected importance of savanna is more based on biodiversity than soil science. In these biomes, you have comparatively large amounts of animal and insect biomass. You have animals constantly eating the plants. This causes deep rooted plants which can regenerate quickly to dominate as they grow back intermittently. The sequestered carbon is mostly in the plants and animals as opposed to soil. Measuring biomass accumulation below ground is more difficult than above ground (counting trees is pretty easy). However some land use pattern studies have looked at which areas have historically been savanna normally show overlap with heavy agriculture regions as the soil is so good. In some cases these former oak savannas in the US will have dozens of feet of fertile topsoil. So there's some speculation that the high soil fertility in such biomes is due to compaction from grazing animals, which I guess is not related to the humus theory, but would be a similar idea about how so much carbon can accumulate.

mrjangles 5y ago

I found a great little link that compares deforestation / reforestation over time for different countries sorted by things like GDP. https://ourworldindata.org/forests-and-deforestation https://ourworldindata.org/forests-and-deforestation As you can see, most wealthy countries have been increasing their forest cover since 1990 (and indeed since the late 1970's though this graph doesn't go back that far). As poorer countries increase their industrial base and means of wealth production, they too will be able to afford to take care of their environments as well as a the West does.

jnmandal 5y ago
Yes, this is exactly what I was talking about. In the US for example, almost all of our historical savanna has been replaced by forests. The upper midwest used to be mostly oak savana biome but since the advent of afforestation those areas, mostly regrow as forest. This shift seems most related to eradication of native species which were able to maintain a system at certain level of ecological succession. So maybe without wolves, bison, passenger pigeons, (maybe even mastodon) these ecosystems aren't able to regrow and we instead get a much less biodiverse forest. There is some suspicion this has been the case for several hundred years as oral history from native American tribes suggests they at one time overhunted these resources and afterwards took an active hand in managing some of these ecosystems. However since the native Americans never cleared these areas they may have been in a better position to maintain them (mostly via controlled fires) whereas modern Americans are often starting with farm fields. Anyways yes, afforestation is happening at good clip but much of it is plantation and a lot of the afforested areas were never previously forest. The same is true in other countries from what I have seen. Even India has massive afforestation but most is agroforestry. A lot still remains to be seen. It's possible that these forests don't make sense as carbon sinks. Savana systems for local agriculture could be more efficient at mitigating carbon emissions. Nearly a third of land is now used for grazing worldwide and much of the output is shipped internationally. Like many other systems in nature and otherwise, it's very complex. So I'm not so sure the 90's era practice of reducing deforestation to simple arithmetic is constructive in an era where scientific community is pushing to maximize carbon sinks.