Increased tropical forest growth could release carbon from the soil

Aug 14, 2011
This is a view through the undergrowth in tropical forest at the study site in Panama. Credit: Dr. Emma Sayer

A new study shows that as climate change enhances tree growth in tropical forests, the resulting increase in litterfall could stimulate soil micro-organisms leading to a release of stored soil carbon.

The research was led by scientists from the Centre for Ecology & Hydrology and the University of Cambridge, UK. The results are published online today (14 August 2011) in the scientific journal Nature Climate Change.

The researchers used results from a six-year experiment in a rainforest at the Smithsonian Tropical Research Institute in Panama, Central America, to study how increases in litterfall - dead plant material such as leaves, bark and twigs which fall to the ground - might affect storage in the soil. Their results show that extra litterfall triggers an effect called 'priming' where fresh carbon from plant litter provides much-needed energy to , which then stimulates the decomposition of carbon stored in the soil.

Lead author Dr Emma Sayer from the UK's Centre for Ecology & Hydrology said, "Most estimates of the carbon sequestration capacity of are based on measurements of tree growth. Our study demonstrates that interactions between plants and soil can have a massive impact on carbon cycling. Models of must take these feedbacks into account to predict future atmospheric levels."

This is leaf litter around the buttress roots of a tropical tree at the study site in Panama. Credit: Dr. Emma Sayer

The study concludes that a large proportion of the carbon sequestered by greater tree growth in tropical forests could be lost from the soil. The researchers estimate that a 30% increase in litterfall could release about 0.6 tonnes of carbon per hectare from lowland tropical forest soils each year. This amount of carbon is greater than estimates of the climate-induced increase in forest biomass carbon in Amazonia over recent decades. Given the vast land surface area covered by tropical forests and the large amount of carbon stored in the , this could affect the global carbon balance.

Tropical forests play an essential role in regulating the global carbon balance. Human activities have caused carbon dioxide levels to rise but it was thought that trees would respond to this by increasing their growth and taking up larger amounts of carbon. However, enhanced leads to more dead plant matter, especially leaf litter, returning to the forest floor and it is unclear what effect this has on the carbon cycle.

Measuring CO2 efflux from the soil in subplots where the forest floor has been replaced with litter with a distinct isotopic signature. A wire mesh tent excludes forest litter from the subplots. Credit: Dr. Emma Sayer

Dr Sayer added, "Soils are thought to be a long-term store for carbon but we have shown that these stores could be diminished if elevated carbon dioxide levels and nitrogen deposition boost plant growth."

Co-author Dr Edmund Tanner, from the University of Cambridge, said, "This priming effect essentially means that older, relatively stable is being replaced by fresh carbon from dead plant matter, which is easily decomposed. We still don't know what consequences this will have for carbon cycling in the long term."

Explore further: Indians rally against climate change ahead of UN talks

More information: ‘Soil carbon release enhanced by increased tropical forest litterfall’ will be published online in the journal Nature Climate Change on 14 August 2011. DOI: 10.1038/nclimate1190

Provided by Centre for Ecology & Hydrology

3.8 /5 (10 votes)

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Techno1
2.1 / 5 (7) Aug 14, 2011
Oh well...

If these findings are true, then warming is pretty much unstoppable at this point.

Increasing plant growth increases CO2 now, eh?

Damned if you do, damned if you don't, so um...

Maybe the earth will vomit us all out.

And the fourth angel poured out his vial upon the sun; and power was given unto him to scorch men with fire.

We are passing 400PPM CO2 soon. I wonder how hot it will be in 2060, when we pass 500PPM CO2?

Hey, Hey, I wonder how hot it will be in 2100, when the earth passes 600PPM CO2?

And hey, if plants growing faster somehow causes soils to release more CO2 faster, than this may all be a vicious cycle which man cannot stop and even has nothing to do with directly.

Above, I assume a slope of 2.0 to 2.1, as it is now. Maybe it just rises faster and faster and faster instead, with plants growing faster and faster, and then soils releasing CO2 as fast as the plants can suck it up.

badger1966
3.7 / 5 (3) Aug 14, 2011
Either this article is incomplete, or it is missing a long term vs. Short term effect. Maybe in short term there is increase in carbon, but as all the organisms die and return their carbon to the Earth and more plants take carbon out the effect, overall would be for more rain forests. This article, or her research, is misrepresenting something.
deatopmg
2.6 / 5 (5) Aug 14, 2011
there's that word "could" again! Send money so we can study the process more.
Caliban
4.2 / 5 (5) Aug 14, 2011
It's good that an attempt is being made here to quantify the amount of carbon released as a result of increased forest growth.

However, I can't help noticing that no effort has been made to develop any ratio of increased soil release vs capture of carbon by the trees and other vegetation, which is the point that Badger is getting at.

This study has managed to isolate and decontextualize a single facet of a complex and interrelated process, to the point of making it meaningless in any real way. The authors of this research might just as well have concluded that turning up the heat on a pot of water will increase its rate of evaporation, for all that the conclusion tells us about anything.
ubavontuba
2.9 / 5 (10) Aug 14, 2011
This is ridiculous. Just where do they think the soil carbon comes from to begin with?

"Soil carbon is the generic name for carbon held within the soil, primarily in association with its organic content."

http://en.wikiped...l_carbon

You simply can't release more carbon than the forest stores in the soil to begin with.

And obviously, a "30% increase in litterfall" is HUGE! And, this litter (plus the living trees, plants, and leaves from which it derives) is primarily made of carbon! Therefore, increasing litterfall 30% just means the forest is storing that much more carbon, overall.

I mean seriously. This is like stating I'll lose weight by eating more! (I wish!)

If anyone buys the "science" in this article, I'll gladly sell them a foolproof and simple method to sequester carbon, for only $100 (cash only). LOL!
Techno1
2 / 5 (5) Aug 14, 2011
Ubavontuba:

It's more complicated than that. Read the article again.

Yes, 30% more litter fall, but the new dead foliage has stored the sunlight as chemical energy, and this material hasn't been depleted by life or other processes in the soils.

So what is happening is the bacteria is getting a big boost of energy from the NEW litterfall, and it gets so much excess energy that not only does it consume the new, but it consumes the old as well, therefore releaseing even more CO2.

Their results show that extra litterfall triggers an effect called 'priming' where fresh carbon from plant litter provides much-needed energy to micro-organisms, which then stimulates the decomposition of carbon stored in the soil


Bad bananas...
ubavontuba
1.8 / 5 (5) Aug 15, 2011
@Techno1:
It's more complicated than that.
No, it's not. If decomposition worked significantly faster in dense litter, you could extrapolate that dense forests would have the same (or even less) ground litter than sparse forests. Look around. This simply isn't true. And even if the microorganisms worked significantly faster, they'd simply run into a fuel limitation as they approached the top litter. It's simply physically impossible for them to indefinitely decompose more "fuel" than they receive.

It's a simple equation. If the mass/density of the forest flora and fauna increases, the forest sequesters more carbon.

Also, the article only relates to tropical forests. Most forests are temperate forests. The ground in temperate forests is significantly cooler, much (or even most) of the year. Microorganisms are significantly hindered by low temperatures.

There's no other way to put it. This article is simply bad science.
ubavontuba
1 / 5 (1) Aug 15, 2011
the new dead foliage has stored the sunlight as chemical energy, and this material hasn't been depleted by life or other processes in the soils.
Right. It's a bunch of stored, condensed carbon.

the bacteria is getting a big boost of energy from the NEW litterfall, and it gets so much excess energy that not only does it consume the new, but it consumes the old as well, therefore releaseing even more CO2.
Again, you run into the limitation of fuel. Also, for this to be true, you would have to establish that dense forests have proportionately less litter than sparse forests. I'm sorry, I'm not going to buy that.

However, I do have this foolproof and simple method to sequester carbon I'll sell you for only $100. Are you ready to place your order? Operators are standing by... LOL!

ubavontuba
1.8 / 5 (5) Aug 15, 2011
And so you know I'm not just making it up as I go along:

"Organic matter tends to accumulate in litter and soils of colder regions such as the boreal forests of North America and the Taiga of Russia. Leaf litter and humus are rapidly oxidized and poorly retained in sub-tropical and tropical climate conditions due to high temperatures and extensive leaching by rainfall."

http://en.wikiped...nk#Soils

Sanescience
not rated yet Aug 15, 2011
With headlines like "Now forest growth releases carbon" is it a wonder that there is so much fodder made by both sides?

I think the USA should join Australia. There are some pretty big mountains made from Olivine/Serpentine. Just start grinding them up, add some water misters and CO2 will get turned into carbonates for construction materials.

I think such schemes are waiting for global carbon credit markets. There going to be waiting for a while.
_nigmatic10
not rated yet Aug 15, 2011
Well. It was only a matter of time before the GW crowd said trees are causing it.
antialias_physorg
4 / 5 (4) Aug 15, 2011
Plants are a zero sum game when it comes to carbon. All they catch is released upon rotting/burning of that plant. Only a minisucule percentage gets sequestered in the soil - and that quickly reaches a saturation point.

The only way to affect the carbon in the atmosphere through plants is to increase the biomass that is present at any one time (i.e. increase the carbon that is concurrently locked in plant matter).

That, too, is a pretty minimal amount when compared to the carbon locked in aquatic organisms (whose carbon content stands a much better chance of being sequestered once those organisms die).

SteveL
5 / 5 (1) Aug 15, 2011
It would likely take a few decades of new growth before there is any significant increase in leaf deposits, by that time the carbon stored in the body, limbs and roots of the trees would far exceed the carbon in the leaves. The only real permanent (for our purposes) carbon sequestration is either through deep burial or tectonic subduction. But, I have yet to hear of anyone storing coal in old coal mines or pumping oil back into the ground.
Noumenon
4.6 / 5 (49) Aug 15, 2011
None of this matters, except as ineffective fodder for the leftist social engineering movement (which is failing). The human condition is far too ingrained in the use of energy, that it would rather go down with the ship, than be forced to fundamentally change it's intrinsic nature, at gun point.

The solution, ...if there is a problem at all,... will not come about through ad-hoc social control of the masses. We have history, which can not be rewritten, to demonstrate the futility of this. The solution will come about through technology and competition between various energy sources.

The science is extremely messy, with endless loose variables, and new things to consider evey day, and questionable data collection. Climate science is light years away from being a precision science. There is no thermostat nor can there be, for the entire planet.

Even if I thought there was merit to AGW, I would say the same thing,... it's just how it is, rather than how I want it to be.
SteveL
5 / 5 (2) Aug 15, 2011
Even if someone doesn't believe humanity is causing global warming; if they have any intelligence at all they should still realize that our world has limited resources and due to our waste products we are basically dumping on our water and food sources. I really don't care so much what the impedus is. We as a species need to change our wasteful ways and begin to think about what we are leaving to those 100 or even 1000 years from now. We need to forget about GOD (or space aliens) saving us from ourselves. This is our mess and we need to grow up a bit and clean up our act. There is no one else to do it for us.
Techno1
3 / 5 (2) Aug 15, 2011
Climate science is light years away from being a precision science. There is no thermostat nor can there be, for the entire planet


Sure there is.

The volume of ice is one of the most absolutes measures you can make for the total heat content of the hydrosphere and atmosphere, precisely because of the fact that the heat of fusion/melting for water is so high; being 80 times the specific heat capacity.

http://igloo.atmo...;sy=2011

So when you see how much less ICE there is now compared to 30 years ago, it means the planet IS warmer, regardless of what caused it...

Noumenon
4.7 / 5 (47) Aug 15, 2011
Climate science is light years away from being a precision science. There is no thermostat nor can there be, for the entire planet


Sure there is.

The volume of ice is one of the most absolutes measures{...}
So when you see how much less ICE there is now compared to 30 years ago, it means the planet IS warmer, regardless of what caused it...


A thermostat is a device used to control temperature and this is was meant, that we can't control the global climate,... not that it can't be measured in principal.
GSwift7
1 / 5 (1) Aug 17, 2011
Plants are a zero sum game when it comes to carbon. All they catch is released upon rotting/burning of that plant. Only a minisucule percentage gets sequestered in the soil - and that quickly reaches a saturation point.


Yes, exactly. If forests acted to continuously remove co2 from the air, all the co2 would have been used up millenia ago. The biosphere is elastic, and acts to maintain an equilibrium. The more growth you have now, the more death you will have tomorrow. By increasing co2 from an outside source such as fossile fuels, you can raise the equilibrium point and accelerate the speed of the cycle. That's generally a good thing for the biosphere, as it equates to an increase in biological activity and therefore biodiversity. It's not always good, but in general it is.

Tropical forests usually have very little topsoil because they are very poor at mineralizing neutrients from litterfall. It's so warm and humid there that it get consumed too fast.
GSwift7
2 / 5 (4) Aug 17, 2011
The volume of ice is one of the most absolutes measures you can make for the total heat content of the hydrosphere and atmosphere, precisely because of the fact that the heat of fusion/melting for water is so high; being 80 times the specific heat capacity


Actually no. Ice volume is highly variable, and subject to short term regional conditions such as wind speed and direction. Total ocean heat content is much more stable on all time scales and is a much better measuring stick. Sea surface temperature is highly variable, but below the apx 700 meter inversion zone, it's very stable and you don't have to worry about phase change conversions. The oceans are the Earth's heat engine and thermostat. They've been doing some unpredicted things lately though. Should be interesting to watch over the next couple decades, now that we have better data thanks to ASOS and ARGOS.
ubavontuba
2 / 5 (4) Aug 18, 2011
Plants are a zero sum game when it comes to carbon. All they catch is released upon rotting/burning of that plant. Only a minisucule percentage gets sequestered in the soil - and that quickly reaches a saturation point.
This simply isn't true. The soil retention of carbon is the largest carbon sink on the planet.

"Soils represent a short to long-term carbon storage medium, and contain more carbon than all terrestrial vegetation and the atmosphere combined."

http://en.wikiped...nk#Soils

And:

"over 2700 Gt of carbon is stored in soils worldwide, which is well above the combined total of atmosphere (780 Gt) or biomass (575 Gt), most of which is wood."

http://en.wikiped...Overview

And speaking of wood, did you know forest products are excellent carbon stores?

"Save the planet! Buy a bigger house and more furniture!" LOL!

GSwift7
2.3 / 5 (6) Aug 18, 2011
This simply isn't true. The soil retention of carbon is the largest carbon sink on the planet.

"Soils represent a short to long-term carbon storage medium, and contain more carbon than all terrestrial vegetation and the atmosphere combined.


Oh good lord, this is one of my BIGGEST pet peevs with you people. How many times do I have to explain the difference between a sink and a store? The largest store of carbon in the world is not the same as the largest sink. The largest sink is the thing with the largest negative flux of carbon. At the present time, that's the ocean. Soil does store a massive amount of carbon, in the form of polycarbonates. However, the soil stays prety close to saturation all the time, so the net flux of carbon going into the soil is NEARLY the same as the flux going out. The difference is very small. The ocean floor accumulates carbon much faster than it is releasing it, making it the largest SINK right now. It's all about flux, not storage capacity.
GSwift7
2.3 / 5 (6) Aug 18, 2011
Plants are a zero sum game when it comes to carbon. All they catch is released upon rotting/burning of that plant. Only a minisucule percentage gets sequestered in the soil - and that quickly reaches a saturation point.
This simply isn't true. The soil retention of carbon is the largest carbon sink on the planet.

"Soils represent a short to long-term carbon storage medium, and contain more carbon than all terrestrial vegetation and the atmosphere combined


continued:

You need to define the term "sequester". When I say "sequester" I'm talking about carbon that is being removed from the carbon cycle. Soil carbon isn't removed from the carbon cycle. It is stored for short to long time periods, as your quote says, but it eventually gets back into the cycle. Only a tiny amount per year is mineralized below the topsoil. If you look at the growth rate of stalagmites and stalagtites in a cave, you can get an idea of the speed at which permanent mineralization happens.
GSwift7
2.7 / 5 (7) Aug 18, 2011
A forest or prarie might become a significant sink on a short time scale, such as 50 to 500 years, but that's nothing in geological time. On time scales over 500 years, forests will be ALMOST neutral. Fires will release carbon, and then the forest will rapidly regrow for 50 to 100 years, then slow down and grow for another 200 to 400 years until it reaches maximum organic density based on available sun and water. Then it levels off at the same storage capacity that it had before the fire or flood. Net change? almost zero, at time scales over 500 years. So, with a net change of almost zero, it isn't a significant sink. It is a significant store, but a store isn't the same as a sink. I hate studies that try to analyze carbon uptake/output rates on short time scales because they massively confuse the average reader.

"Save the planet! Buy a bigger house and more furniture!" LOL!


just dump all our papar waste into the ocean. That is best.
ubavontuba
1.8 / 5 (5) Aug 19, 2011
How many times do I have to explain the difference between a sink and a store? The largest store of carbon in the world is not the same as the largest sink.
But it is a sink, especially in the temperate forests:

"Organic matter tends to accumulate in litter and soils of colder regions such as the boreal forests of North America and the Taiga of Russia."

http://en.wikiped...nk#Soils

"Forests are carbon stores, and they are carbon dioxide sinks when they are increasing in density or area. In Canada's boreal forests as much as 80% of the total carbon is stored in the soils as dead organic matter."

http://en.wikiped...#Forests

And, forest density is increasing:

http://www.physor...ing.html

(especially notice the robust growth of the treeline in the distance!)
ubavontuba
1 / 5 (2) Aug 19, 2011
just dump all our papar waste into the ocean. That is best.
Right. Like that's not likely to have any negative side effects (sarcasm).
ubavontuba
1 / 5 (1) Aug 19, 2011
You need to define the term "sequester". When I say "sequester" I'm talking about carbon that is being removed from the carbon cycle.
I would argue that transitional storage is a relatively permanent form of storage. As a dead tree decays, it's mass is replaced by new trees.

GSwift7
2 / 5 (4) Aug 19, 2011
From your own quotes, a forest is only a significant sink when it is increasing in density. They are currerntly increasing in density because they are returning to the way they were before we deforested them. It's just going back to its original long-term state. Once they do return to that maximum density, they stop being a significant sink, and are just a store again.

Your own sources say that. I'm not espousing some wild fringe theory here. This is mainstream stuff, commonly agreed amongst both skeptics and non-skeptics alike. This isn't an area where there is much disagreement.

My comment about dumping paper into the ocean was an absurd joke, of course.

I really don't think we are disagreeing on this aside from the fact that you refuse to define a sink versus a source on long time scales rather than short ones. In the story above, they are saying that tropical forests can be sources rather than sinks. They are still big stores, even if they become temporary sources though.
GSwift7
2.6 / 5 (5) Aug 19, 2011
If you insist on looking at short time scales, then forests are sources of carbon as often as they are sinks. The long term balance is nearly neutral. On short time scales, the times of expansion and increasing density are balanced by fires, tree disease outbreaks, insect plagues, and of course human destruction. So, on short time scales, you would be equally correct to call a forest a sink or a source, depending on what little slice of time you're looking at and where. Peat bogs and swamps are much better sinks than forests, as they are a better mechanism for mineralization of carbon. As I have said from the beginning, forests are a sink on long time scales, but not a big one. It's just really slow compared to the ocean bottom, where more carbon is removed from the cycle than anywhere else.

I like trees and forests. I love to hike, camp and canoe. I strongly support forest conservation, and it's one of the few causes I give money to. That doesn't make them a sink though.
GSwift7
1 / 5 (1) Aug 19, 2011
I would argue that transitional storage is a relatively permanent form of storage. As a dead tree decays, it's mass is replaced by new trees.


That is technically correct, but if you want to look at it that way, then the air also counts as transitional storage. It is more in line with conventional definitions of the terms to count soil organics and airborn carbon as part of the active carbon cycle, and not sequestered.
ubavontuba
1.8 / 5 (5) Aug 19, 2011
{q]From your own quotes, a forest is only a significant sink when it is increasing in density. They are currerntly increasing in density because they are returning to the way they were before we deforested them. This would suggest we're using significantly less forest products than ever before. This seems unlikely.

The article I provided states: "Even in the South American nations studied, more density helped maintain regional carbon levels in the face of deforestation."

So it's not like the tress are suddenly safe from our saws.

And I've seen lots of old pictures of North American, pristine (unlogged) forests compared with new pictures of the same forests. The density change is quite apparent.

ubavontuba
1 / 5 (1) Aug 19, 2011
I really don't think we are disagreeing on this aside from the fact that you refuse to define a sink versus a source on long time scales rather than short ones
Perhaps, but I think the forests have been around a long time - by any measure.

In the story above, they are saying that tropical forests can be sources rather than sinks.
I disagree. If you have a 30% increase in litter, you're likely to have a proportionate increase in biomass as well (unless you would argue the trees have gotten smaller and are sprouting more leaves - just because). This increased biomass represents a sink.

The long term balance is nearly neutral.
It varies with growing conditions. Right now, the biosphere is booming:

http://wattsupwit...e-cause/

And, did you read about the million year old mummified forest in the Arctic?

http://www.physor...ees.html

ubavontuba
1.8 / 5 (5) Aug 19, 2011
Correction. This was supposed to appear as follows:

From your own quotes, a forest is only a significant sink when it is increasing in density. They are currerntly increasing in density because they are returning to the way they were before we deforested them.
This would suggest we're using significantly less forest products than ever before. This seems unlikely.

The article I provided states: "Even in the South American nations studied, more density helped maintain regional carbon levels in the face of deforestation."

So it's not like the tress are suddenly safe from our saws.

And I've seen lots of old pictures of North American, pristine (unlogged) forests compared with new pictures of the same forests. The density change is quite apparent.

ubavontuba
1.8 / 5 (5) Aug 21, 2011
Here's a site which contains lots of those Sierra forest photo comparisons I mentioned:

http://www.ridgel...ject.htm
GSwift7
2 / 5 (4) Aug 22, 2011
I disagree. If you have a 30% increase in litter, you're likely to have a proportionate increase in biomass as well (unless you would argue the trees have gotten smaller and are sprouting more leaves - just because). This increased biomass represents a sink.


Are you saying that you don't think the article says that, or are you saying that you think they are wrong?

The researchers estimate that a 30% increase in litterfall could release about 0.6 tonnes of carbon per hectare from lowland tropical forest soils each year. This amount of carbon is greater than estimates of the climate-induced increase in forest biomass carbon


When the carbon released is greater than the carbon taken in, that's a source, though they didn't use the word 'source'.

If you're saying that you question their conclusions, then I'm with you on that one. More atmospheric carbon seems like it would affect soil solubility and force more to be held in soil. That seems obvious to me.
GSwift7
2 / 5 (4) Aug 22, 2011
Yeah, I'm with you on the deforestation thing too. Overall, we're stripping the forests globally. There are a few areas that are growing back though, like the northeast US. There's a bunch of former farmland that's been abandoned and returned to forest in the past 50 years. That's generally not the case elsewhere though. It is pretty rare these days in the US to see anyone clear a forest in order to make a farm. The conservation agencies have been noticing that northeastern lakes are suffering because of the rapid reforestation up there. The rotting biomass is causing lake acidification as water carries chemicals through the soil into the lakes. I guess it's a good problem to have, and not likely to be permanent, as the forests will eventually reach max density again and it 'should' all balance back out.
GSwift7
1 / 5 (1) Aug 22, 2011
Perhaps, but I think the forests have been around a long time - by any measure.


In the case of tropical forests, yes, for the most part. In the case of boreal forests on the north american and eurasian continents, no. The whole northern hemisphere was a baren moonscape with not even sparse grass growing on it as recently as 10,000 years ago. The receding ice sheets left behind nothing but bare rock in most places. For example, the part of California where the giant redwoods now grow. It took as much as 1000 years after the ice receded before trees came back, and then it was another 1000 before the primary trees you see there now took hold. Most people don't know that. It's undisputed fact though.
ubavontuba
1.8 / 5 (5) Aug 22, 2011
Are you saying that you don't think the article says that, or are you saying that you think they are wrong?
I think it's clear the article ignores the necessity for a sustained increase in biomass to accomplish the 30% increase in litter.

When the carbon released is greater than the carbon taken in, that's a source, though they didn't use the word 'source'.
I don't buy it. If the carbon released is greater than the carbon taken in, the biomass/forest mass must necessarily decrease and the litter mass must necessarily decrease as well. It would be self regulating. As I indicated above, you're going to run into fuel limitation problems.

If you're saying that you question their conclusions, then I'm with you on that one.
That is what I'm saying. Their observations must be self-limiting. It's like putting more wood on a fire to make it burn hotter. It works for awhile, until you run out of wood altogether.
ubavontuba
1 / 5 (1) Aug 22, 2011
More atmospheric carbon seems like it would affect soil solubility and force more to be held in soil. That seems obvious to me.
Oh, I don't know about that so much as I think the flora would certainly benefit from the carbon rich atmosphere.

The whole northern hemisphere was a baren moonscape with not even sparse grass growing on it as recently as 10,000 years ago.
I disagree with this. Those woolly mammoths had to eat something!

It's true the sequoia were nearly wiped out by the ice age, but small pockets survived in California because the prevailing winds (from the relatively warm ocean) protected them from the deep freeze.

GSwift7
2 / 5 (4) Aug 23, 2011
I think it's clear the article ignores the necessity for a sustained increase in biomass to accomplish the 30% increase in litter.


Agreed. Any effect they observe would be short-lived anyway. The forest should return to whatever equilibrium state it was at previously, after adjusting to any short term change. Of course, in reality, it changes constantly, from day to day, week to week, year to year. I read an article on the subject once that made an interesting point, which I wasn't aware of. They said that densely packed plants, such as corn in a field or a tropical canopy, will consume all the available co2 very quickly without wind to mix the air, then they essentially shut down. They also stop consuming co2 at night, of course, and will actually 'exhale' some without the sun to drive photosynthesis.
GSwift7
2 / 5 (4) Aug 23, 2011
I don't buy it. If the carbon released is greater than the carbon taken in, the biomass/forest mass must necessarily decrease and the litter mass must necessarily decrease as well. It would be self regulating.


I agree with that 100% too. The forest 'system', which includes microorganisms, insects, animals, etc will generally have some organism in every available nich where there is a food source. It's highly elastic and self-regulating, based on available sunlight, water, soil chemistry, etc. As I said in the previous post, whatever they observed with this experiment would be a tiny little blip in a great big system, hardly noticeable in the grand scheme of things. They wasted their time.
GSwift7
2 / 5 (4) Aug 23, 2011
More atmospheric carbon seems like it would affect soil solubility and force more to be held in soil. That seems obvious to me.
Oh, I don't know about that so much as I think the flora would certainly benefit from the carbon rich atmosphere


Wouldn't it make logical sense that if you increase the co2 in any one part of the system, you should see all the other parts of the cycle also end up with more carbon? Just like in the ocean. Higher co2 in the air leads to more carbonates (which is what causes the acidification) in the water. Soil chemistry isn't much different from the ocean in that regard. More co2 in the air would mean more chances for chemical reactions which form polycarbonates in the soil.
GSwift7
2 / 5 (4) Aug 23, 2011
I disagree with this. Those woolly mammoths had to eat something!


That was afterwards. At the peak of the ice age there were litterally miles of ice, and it extended all the way down to about half way down the USA. You can see boulders scattered around in the north which were dropped by the ice when it melted, and which obviously didn't come from any local formations. For example, a 60 ton chunck of gray granite in an area where there's no granite for a thousand miles. The ice sheets were unbroken accross all of canada. Those forests are very new. It took centuries for small plants to spread back north. Look at places where smaller glaciers have receded in recent times. The scree of rocks and boulders, with almost zero life was the condition of the majority of north america for a very long time. The mammoths lived south of the ice.
GSwift7
2 / 5 (4) Aug 23, 2011
I did some more reading on the subject of ice age conditions and conditions following the most recent glacial period. It seems that Alaska remained ice free because it was too arid, though it was plenty cold. a good chunk of area along the northern midwest was a giant glacial lake. The central US was polar desert. East US was taiga/permafrost. A good chunk of the west was temperate desert. You are correct that parts of california remained ice free. I was correct about canada being totally stripped down to bedrock though. There's a color-coded map on wiki:

http://en.wikiped...l_period

Cool stuff. Have a look and let your imagination try to grasp that world. wow. It's hard to read some of the similar colors though.
ubavontuba
1 / 5 (1) Aug 24, 2011
The mammoths lived south of the ice.
It's a wonder then, that so many have only just emerged from the Siberian permafrost. How did they get there?

From your glacial period source:
"The last glacial period was ...from approximately 110,000 to 10,000 years ago."

But:

"Radiocarbon dating determined Dima died about 40,000 years ago."

And:

"(Lyuba) was discovered encased in a layer of permafrost near the Yuribei River in Russia, where it had been buried for 37,000 years."

http://en.wikiped..._remains

So, if your source is correct, woolly mammoths lived on mile thick sheets of barren ice, and were magically transported to the base of the glaciers and buried in the Siberian permafrost?

See? This is what I didn't like about the article. So much information is ignored and dismissed as being unimportant.

ubavontuba
1 / 5 (1) Aug 24, 2011
Wouldn't it make logical sense that if you increase the co2 in any one part of the system, you should see all the other parts of the cycle also end up with more carbon?
I doubt forest floors are very permeable to atmoshpheric carbon, already outgassing and being so saturated with carbon as it is.

But, if the system is capable of storing more carbon, it certainly will. That's why you need to consider temperate and boreal forests in relation to this article. They can, and do, continually store carbon. A 30% increase in litter from them, would amount to 30% more biomass lying about.

In boreal forests it's cold, so the temperature acts as a preservative. And conifer needles acidify the soil, reducing the rate of decomposition even further. Adding more needles would only serve to compound this effect.

antialias_physorg
5 / 5 (1) Aug 24, 2011
Wouldn't it make logical sense that if you increase the co2 in any one part of the system,

When it comes to storing CO2 the forsts are pretty much negligible. The overwhelming majority of CO2 is stored in the oceans (about 93%). Forests are pretty much a "2D" storage - being not much more than a biofilm a few meters high, whereas the oceans are more of a "3D" storage. Small temperature changes in the oceans affect solubility of CO2 (and thereby atmospheric CO2 content) to a much greater extent than deforestation could.
GSwift7
2 / 5 (4) Aug 24, 2011
I doubt forest floors are very permeable to atmoshpheric carbon, already outgassing and being so saturated with carbon as it is.


don't forget about rain/gound water. Any increase in airborn co2 will be transfered into the soil immediately by water, in direct proportion to atmospheric concentration. It's an elastic system that tries to stay in a dynamic equilibrium.
GSwift7
2 / 5 (4) Aug 24, 2011
They can, and do, continually store carbon. A 30% increase in litter from them, would amount to 30% more biomass lying about


It's basically the same mechanism as in the tropics, just slower. If you increase litterfall it will still eventually reach a new equilibrium point. There is a finite limit to how much topsoil will form in a given region, no matter how long it is able to accumulate. There's usually clay beneath, in the boreal locations you are talking about, then bedrock. Organic (carbon) material is a food source for soil organisms. If there is food, then there will be organisms to fill all the available niches and consume the food. That even happens under the most extreme conditions, such as mid-ocean vents.
GSwift7
2 / 5 (4) Aug 24, 2011
to antialias:

Yes, exactly. Pro-forest conservation efforts would like for forests to be perceived as "good", but I think they are actually detracting from the true measure of the value of forests, for their beauty and diversity, when they try to mix forests into the global warming debate. It's like trying to say that you should buy a Ferrari because they have really nice carpet on the floors. Seems a shame to me.
GSwift7
2 / 5 (4) Aug 24, 2011
Here's a bizzarre twist that'll make your brain seize up:

I was listening to a nature show on NPR yesterday. They had a naturalist/bird expert from Clemson University on the show. A listener called in to ask why a certain type of bird doesn't ever come to her feeders any more. The answer was because those birds are in massive decline on the east coast, and maybe in danger of regional extinction. Why? Reforestation. There's lots of former farmland on the east coast that is being allowed to return to forest, leaving a diminished habitat for grassland birds that have taken hold here in the past couple centuries. It's really just going back to the way it was, but certainly not good news for those types of birds. Probably affects a few other species like rodents and reptiles too, but it was a bird show, so that's all they were talking about. Extinctions from reforestation. Not what the tree-huggers want to hear or publicize.
antialias_physorg
5 / 5 (1) Aug 24, 2011
Extinctions from reforestation.

Forests, however, are a much richer habitat than grasslands. So for every species that gets pushed back by reforestation you have two species which find a habitat (don't quote me on that ratio but I'm willing to wager it's better than 1-to-1).

And there is enough farmeland still in use - so those grassland species are hardly in danger of going extinct.

Forests do have their role to play in global warming, though: They soak up heat (the air over forests is always cooler than over fields or cities)...just not so much with the CO2-issue.
GSwift7
2 / 5 (4) Aug 24, 2011
Forests, however, are a much richer habitat than grasslands. So for every species that gets pushed back by reforestation you have two species which find a habitat (don't quote me on that ratio but I'm willing to wager it's better than 1-to-1).

And there is enough farmeland still in use - so those grassland species are hardly in danger of going extinct


Yes, I'm sure the forest is better.

Actually those grassland species are in danger, according to the guy yesterday. He said he hasn't seen any of the specific type of bird he was talking about in several years. It's a major concerne, according to him. He said that that bird is the most rapidly declining bird in north america.
antialias_physorg
5 / 5 (1) Aug 25, 2011
t's a major concerne, according to him. He said that that bird is the most rapidly declining bird in north america.

Well, no matter what there will always be one "most rapidly declining" species.
He should be talking about total numbers of declining species and seeing which group (as pertaining to habitat type) are the ones most at risk.

Reminds me a bit of what a friend of mine once told me (he's an MD): 100% of people die. There will always be one disease/condition which is the major killer. Eliminate one disease and another will become more prevalent (not because it suddenly becomes more deadly but just because those who would have died of the other - now curable - disease now have more time to develop another disease.)
ubavontuba
1.8 / 5 (5) Aug 25, 2011
It's an elastic system that tries to stay in a dynamic equilibrium.
Exactly. This is why the forest floor isn't likely to absorb more CO2 from the atmosphere, should atmospheric CO2 increase. The forest floor is generally the source for atmospheric CO2 in the forest. It's outgassing, not absorbing CO2.

Rain might drive more CO2 into the forest floor temporarily, but as it evaporates it'll allow the CO2 to escape. The exception is water which infitrates and becomes ground water. It takes carbonates deep into the soil, but it's a very slow process and the volume isn't likely to increase as a result of atmospheric CO2, as the carbonates already reside in the soil.

ubavontuba
1 / 5 (1) Aug 26, 2011
It's basically the same mechanism as in the tropics, just slower. If you increase litterfall it will still eventually reach a new equilibrium point.
Right. But the growth required to sustain the increased litterfall represents a corresponding increase in biomass, and hence an increase in carbon storage.

That's sad about the birds. The landscape is changing rapidly everywhere though.

I watched a PBS show about a wolf hunt in the late 1800's ("Lobo the King of Currumpaw"). The pictures of New Mexico from the time showed a rather barren landscape. The modern video footage shows tremendous amounts of grass and brush in the same locations.

Anecdotally, increased atmospheric CO2 seems to be great for the flora and fauna around my house too. I can hardly keep up with the tree trimming and brush cutting. I'm half expecting Tarzan to swing by, any minute!