From the Centre for Ecology & Hydrology
Increased tropical forest growth could release carbon from the soil
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 carbon 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 micro-organisms, which then stimulates the decomposition of carbon stored in the soil.
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  IMAGE: 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…
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Lead author Dr Emma Sayer from the UK’s Centre for Ecology & Hydrology said, “Most estimates of the carbon sequestration capacity of tropical forests 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 climate change must take these feedbacks into account to predict future atmospheric carbon dioxide levels.”
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 soil, this could affect the global carbon balance.
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 IMAGE: This is leaf litter around the buttress roots of a tropical tree at the study site in Panama.
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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 tree growth 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.
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 soil carbon 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.”
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A rather circular argument about nothing with no consequences, are they trying to prove that nature is trying to destroy us!!! WTF CO2 will and has been increasing biomass world wide big time. The world has been running on almost empty for so long and when the world starts to bloom they have a pink fit. What do these greenies really want?
Let me get this straight, the carbon offset I might pay for my flight goes towards growing trees, which releases more carbon? It has taken them 6 years to work out that if you have more/bigger trees you have more leaf litter??? if one of my undergrads had written this I wouldn’t be impressed.
This is turning into a joke.
Models of climate change must take these feedbacks into account to predict future atmospheric carbon dioxide levels.
Maybe the models should take this into account to determine the current carbon dioxide levels that are not attributed to mankind.
“Things are not worse than we thought.”
Does common sense go out of the window when any “scientific” research involving carbon dioxide takes place? Or can I be truly cynical and ask if this research is an attempt to prove that planting more forests cannot undo the bad things that mankind has done to the planet, therefore we need to be taxed more to prevent us flying and using our cars?
The Carbon Cycle is a vital recycling process and we are finding out more and more about it. As to this research proving a possible extra climate driver or being a ‘danger’ or whatever alarmist claptrap that will now appear I say ‘So What’.
This process has been in operation for billions of years and recent learning about a small part of it does not change anything. Especially the reality that carbon dioxide does NOT drive climate.
It does drive plant growth and as far as plants are concerned the more the better.
The bleeding system has worked for billions of years. Now Johny come lately man briefly enters onto the scene postulating this way, then that way. Give me a break! I will settle for Pythagoras theorem where the “sum of the squares……”
The science is settled.
The science is settled.
The science is settled.
What part of that do these researchers not understand?
“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.””
So – plants remove CO2 from the atmosphere, more plants do not. Is this the vegetation/CO2 tipping point that climate catastrophists have been waiting for?
This kind of statement goes beyond simple error into Monty Python territory. It would be funny if they weren’t spending our money on this astonishing nonsense.
Once the carbon is released from the soil, what happens next? There is a LOT of green leaves above… Of course, at nights there will be net CO2 release to the atmosphere, but during the daytime? So release of CO2 from the soil is one thing, and what happens next is another thing.
I hope no one advises to cut as much of rain forrest as possible (as a result of this research) 🙂
So, um… chop down the rainforests?
Seems to me this is beneficial to a forest… a natural source of food just wafting up from the ground. Maybe it’s the way they’re supposed to be.
Man, I’m sure glad I’m not one of those people that panics every time I hear about another source, or potential source, of Carbon Dioxide… they’re finding it everywhere these days. Next it will be found outgassing from Coke and Mountain Dew…
That’s just plain funny. They’ve gone and created their own custom-made ‘tipping point’!
1. Climate change causes trees to grow (they don’t reveal how they can tell this).
2. More trees=more leaf litter=more humic acid=more ‘carbon’. (it’s not enough that the poor element is maligned by terminology misuse)
3. More ‘carbon’ gets released, causing more climate change. Brother.
When will it all just shut up and go away?
No such thing as a free lunch. Soils known to be rich in available organic carbon are usually productive. Part of this is because they consume soil carbon much as described and possibly by other cycles. Part is because the carbon helps increase the cation exchange capacity of the soil (its ability to hold nutrients before they are flushed down the creek).
Any competent geochemist will tell you that organic carbon does not accumulate in soils with time. It plateaus out at about 2% by weight, with higher values in the rare terra preta and lower values in desert sands. This is because we are dealing with a dynamic system with a number of competing reactions whose individual rates can vary, in ways that have not been measured and identified so often.
The thought that one can sequester carbon in soils or trees is true only so long as the trees are maintained at or near maximum carbon yield weight per hectare of tree and when other soil nutrients are not severely limiting. You cannot harvest forest and grow new trees in a ‘sustainable’ way because each tree you take from the property has a weight of carbon, phosphorus, potassium, calcium, trace elements and so on. These become depleted unless artificial fertiliser (usually) or mulch (so old fashioned) is applied.
So stay well clear of snake oil salesmen asking you to invest in tree plantations for carbon credits. Such schemes will usually carry the seeds of their destruction, but have the advantage that they are likely to outlast the salesman, who would make a rounded fertilizer by himself. (True – 100 years ago, boatloads of mummified cats were shipped from Egypt to England for fertilizer.)
1. Dump leaves under a plastic tent for a couple of years.
2. ???
3. Profit!
Hook a dynamo up to Galileo’s corpse, we’ll have all the energy we need.
…”it is unclear what effect this has on the carbon cycle.”
:…”we have shown that these stores could be diminished if elevated carbon dioxide levels and nitrogen deposition boost plant growth.”
“We still don’t know what consequences this will have for carbon cycling in the long term.”
Obviously, more long- term grant money is needed for further study.
This is the start of the “more CO2 is bad” even if it doesn’t cause CAGW meme.
Gosh! Whatever next? Question: CO2 is a massy molecule. There is not a lot of wind (I am led to believe) inside rain forests. Will this newly released CO2 rise above the canopy to become “well mixed” at levels being measured on the forest floor?
“We still don’t know what consequences this will have for carbon cycling in the long term”
Try “None”, leaves have been falling off trees ever since trees were invented! Nature seems to have managed OK thus far without a six year study.
So, replanting the amazon is a BAD thing.
So, let’s get this straight…. we’re told that the biosphere absorbs about half of the extra co2 we sinning humans have put into the atmosphere from burning fossil fuels. But this is now found to be impossible because although measurement shows biomass has increased 7% in 30 years, the additional leaf litter causes bugs in soil to release more co2 than the additional biomass absorbs?
Doesn’t look like settled science to me.
So this would have some implications for the backyard mulch pile, correct? I’m so confused. Should I burn my annual leaf fall? Maybe I should burn my tree’s to prevent leaf litter, and pave over everything. What to do, what to do.
“the resulting increase in litterfall could stimulate soil micro-organisms leading to a release of stored soil carbon.” Or, it could not!
“dead plant material such as leaves, bark and twigs which fall to the ground – might affect carbon storage in the soil.” Or, it might not!
“Our study demonstrates that interactions between plants and soil can have a massive impact on carbon cycling. Models of climate change must take these feedbacks into account to predict future atmospheric carbon dioxide levels.” Or, it can not! Oh & what’s with the “prediction”, Mystic Meg, or should it be Septic Peg??
“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”. Have they? By how much? What percentage of the total atmospheric Carbon Dioxide is attributable to them? Perhaps the original “was thought”, was wrong!
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.” Was that “thought” right? Could, if?
“We still don’t know what consequences this will have for carbon cycling in the long term.” You don’t know? Still? After 20 years & billions of dollars & pounds & every other currency known to humanity being flung at it? More improtantly, it is obvious to anyone that this priming malarky has been going on for millions of years in none ice-bound areas & interglacials 🙂
Cambridge is not a million miles from Norwich (UEA), you know (about 56 miles WSW as the proverbial crow flies!) & Norfolk borders Cambridgeshire!!! They’re practically kissin’ cousins, geographically speaking!!!!! Perhaps some of the bizarre thinking going on at UEA has percolated through the ether to Cambridge, who knows?
“Human activities have caused carbon dioxide levels to rise” is one of those throwaway remarks that might persuade some to believe it is substantial and produces harmful effects; but we here all know different: carbon dioxide is harmless, nay, beneficial, and doesn’t to any real extent cause warming. Unfortunately, until the sceptic side finds someone able to say so in a form that has some force and gets noticed, we shall go on hearing the same old same old for years and years.
A small plant or a huge tree – it’s all the same principle: they are simply part of a carbon CYCLE. What drops to the ground from the trees is only what came out of the ground (and the air) in the first place. And don’t even get me started on microbes. Or termites. Or cows. It’s a CYCLE, STUPID!
The lesser amount of stored carbon in the soil is counterbalanced by the greater amount of carbon stored in the greater number of micro-organisms.
Is it proper to call greater CO2 levels, “climate change”?
It’s a conspiracy I tell you! This is how the plants are take over the planet
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