CO2 Is Greening The Planet: African Savannahs Getting a Makeover to Forests

Umbrella Thorn Acacia, Lake Nakuru National Park, Kenya Photographic Print

Umbrella Thorn Acacia, Lake Nakuru National Park, Kenya
by Adam Jones – click to order a photo or poster

I’ve covered this before, such as when NASA posted satellite data showing that the biosphere is booming thanks to CO2 fertilization. This new study from Goethe University in Frankfurt, Germany suggests that the Umbrella Thorn Acacia trees will make a comeback.

Tree trumps grass to rule the savannas

A new study published today in “Nature” by authors from the Biodiversity and Climate Research Centre and the Goethe University Frankfurt suggests that large parts of Africa’s savannas may well be forests by 2100. The study suggests that fertilization by atmospheric carbon dioxide is forcing increases in tree cover throughout Africa. A switch from savanna to forest occurs once a critical threshold of CO2 concentration is exceeded, yet each site has its own critical threshold. The implication is that each savanna will switch at different points in time, thereby reducing the risk that a synchronous shock to the earth system will emanate from savannas.

Tropical grasslands, savannas and forests, areas the authors call the savanna complex, are expected to respond sensitively to climate and atmospheric changes. This is because the main players, grasses and trees, differ fundamentally in their response to temperature, carbon dioxide supply and fire and are in an unrelenting struggle for the dominance of the savanna complex. The outcome of this struggle determines whether vast portions of the globe’s tropical and sub-tropical regions are covered with grasslands, savannas or forests.  In the past such shifts in dominance have played out in slow motion, but the current wave of atmospheric changes has accelerated the potential rate of change.

Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.  “However, most of these studies were conducted in northern ecosystems or on commercially important species” explains Steven Higgins, lead author of the study from the Biodiodversity and Climate Reseach Centre and Goethe-University. “In fact, only one experimental study has investigated how savanna plants will respond to changing CO2 concentrations and this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations, and that their growth really starts taking off at the CO2 concentrations we are currently experiencing.“

The vegetation shifts that the Higgins and Scheiter study projects are an example of what some theorists call catastrophic regime shifts. Such catastrophic regime shifts can be triggered by small changes in the factors that regulate the system. These small changes set up a cascade of events that reinforce each other causing the system to change more and more rapidly. The study demonstrated that the savanna complex showed symptoms of catastrophic regime shifts.  “The potential for regime shifts in a vegetation formation that covers such vast areas is what is making earth system scientists turn their attention to savannas” comments Higgins.

Knowing when such regime shifts will occur is critical for anticipating change. This study discovered that locations where the temperature rise associated with climate change occurs rapidly, for example in the center of southern Africa, are projected to switch later to forest as the high rate of temperature increase allows the savanna grasses to remain competitive for longer in the face of rising atmospheric CO2 concentration. This means that even though a single location may experience its catastrophic regime shift, the vegetation change when averaged over a region will be smoother. Such gradual transitions in regional vegetation patterns will reduce the potential for shocks to the earth system. “While this may seem reassuring, we have to bear in mind that these changes are still rapid when viewed on geological time scales”, says Higgins.

The practical implications of the study are far reaching. For example, the study identified a belt that spans northern central Africa where fire suppression would encourage savannas to transition to forests. “So if you wanted to sequester carbon as part of a carbon mitigation action, this is where you should do it” explained Higgins “with the caveat that where this will work is shifting as atmospheric conditions change.” A worrying implication is that the grasslands and open savannas of Africa, areas with unique floras and faunas, are set to be replaced by closed savannas  or forests.  Hence it appears that atmospheric change represents a major threat to systems that are already threatened by over-grazing, plantation forestry and crop production.

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Paper:

Steven I. Higgins and Simon Scheiter (2012). Atmospheric CO2 forces abrupt vegetation shifts locally, but not global. Nature, DOI: 10.1038/nature11238

download PDF, 116 KB

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Jeff

Hopefully we are equally skeptical of models that promise good news a century from now

Christian

So forestation and de-forestation are both bad things……or do I read this the wrong way?

Peter

Could the decimation of the large animal population of the Savana have anything to do with this uptick in tree growth? I would think the former large Elephant population could not have been all that friendly to slow growing trees. And what about increased urbanization of the Indiginous population? Seems that there might be numerous factors that might be at play here.

DirkH

“A worrying implication is that the grasslands and open savannas of Africa, areas with unique floras and faunas, are set to be replaced by closed savannas or forests. Hence it appears that atmospheric change represents a major threat”
Save the barren wastelands of the planet from the threat of wuthering vegetation!

Steve Keohane

Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.
Which planet have the flora they are referring to?

KevinM

You must read old articles on “Musings from the ChiefIO” with subjects like
“CO2 is plant food”. There are lots of them, and many are humorous as well as informative.
e.g. http://pindanpost.com/2012/07/01/co2-is-plant-food-part-66-for-those-who-doubt/
And just why do greenhouses pump in CO2 if “Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.”

Hasbeen

It’s the lack of elephants, natures bulldozer, that’s the problem.

steveta_uk

Interesting redefinition of the word “catastrophic”.
Apparently gradual catastrophes are likely.

Rob Potter

I think Peter (@7.45) has it correct – the incerase in trees is a result of decreased grazing. You can see this anywhere there is a reduction in grazing animals and I don’t suppose African savannah’s are any different to other grasslands.
Their early statement is pretty bizarre “Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.” Are they trying to say that all the glasshouse growers are wasting their money and that the collection of papers on CO2 Science are not experimental studies?
This smacks of an attempt at finding the cloud in the silver lining……

johnmcguire

Anthony, I take it you read nature mag for the humor factor. But they are not even a good joke.

Jer0me

I am constantly amazed that these people have created their own illusory ‘static’ nature. Nature changes all the time (the real thing, not the magazine). This is how and why life changes. We should rejoice in more diverse habitats and opportunity for life, but suddenly it’s a Bad Thing.
Sheesh!

Meyer

Only a modelist would think trees are catastrophic.

“this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations”
================
So, it would appear that Al Gore, the Team, Climate Science and the IPCC, in wanting us to cut back to per-industrial CO2 levels, are in fact advocating that we starve trees.

Chris Mortimer

Looks like a natural cycle to me.
Trees grow – locals burn the trees for fuel (no alternative due to the green brigades madness) – more co2 plant food released – trees grow etc etc.

Pamela Gray

The “tree-ing” of savannas probably isn’t due to CO2 increase as much as it is due to ENSO oceanic-atmospheric oscillations providing necessary growing conditions for trees. And it could also be related to an increase in whatever animal spreads the seeds into the savanna. For example, might tree eating animals such as giraffs, be on the increase due to better preservation efforts? Animals like that are great seed spreaders.

mikerossander

re: “Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.”
Does Higgins source that assertion? Because it would appear to be directly contradicted by the Science magazine article discussed here just a few days ago (Susanne von Caemmerer, W. Paul Quick, and Robert T. Furbank (2012). The Development of C4 Rice: Current Progress and Future Challenges. Science 336 (6089): 1671-1672.)

reducing the risk that a synchronous shock to the earth system will emanate from savannas.
Wow, that is a risk I would never have thought of…boy what great imagination! Catastrophic regime shifts? Are they expecting a Coup? Just think…those devilish savannahs, lurking…lurking, ready to pounce synchronously and shock the earth. Diabolical!
Jer0me says:
July 2, 2012 at 8:24 am
“I am constantly amazed that these people have created their own illusory ‘static’ nature.”
The most fundamental assumption of climate change alarmism: Change from some apparently immutable base line, one so small as to be hidden by the error bars. Yet it marches on, ambushing, er, or rebushing, savannahs everywhere. Shocking!

More baffle gab from the model people. My experience in the parkland of Alberta and Saskatchewan tells me fire is the most important component followed by moisture in the grasses vs trees balance. Something, by the way, known for generations.

eqibno

What a dilemma!
More trees due to that evil changing climate…. We can’t have that! We must reduce CO2 so that we keep those lovely grasslands as they are…errr were…errr should be?
My question is: Will the Greens cut down the offending trees in the meantime to give the poor old grass a chance?
They may have to ask industrialists to sustainably harvest the trees (using green methods, of course) to keep the exact number that used to be where they believe it should be….

pat

The spread of acacia may cause a dramatic difference, if true. Once established it is extremely hardy, with the deepest root system of any flora, it can reach down to a water table and is salt tolerant. In most places it does not create a dense forest, but rather a scattered tree line. But it hosts a large variety of fauna, including honey bees that will further impact. Both the leaves and green seed pods are edible. The mulch ring, while not great, will allow moisture retention and cooler temperatures.

Steve C

Love the bit about “reducing the risk that a synchronous shock to the earth system will emanate from savannas”. Sounds pretty much like nature’s usual gradual re-accommodation to change to me, but of course “gradual” doesn’t sound very scary, unlike “synchronous shock” talk.

phlogiston

Jer0me says:
July 2, 2012 at 8:24 am
I am constantly amazed that these people have created their own illusory ‘static’ nature. Nature changes all the time (the real thing, not the magazine). This is how and why life changes. We should rejoice in more diverse habitats and opportunity for life, but suddenly it’s a Bad Thing.
Sheesh!

You are right, large areas of Africa have alternated regularly from forest to Savannah over the last million years or so.
We are seeing here the “the world was created in 1850” mindset of the AGW camp.
The only creative challenge in these people’s minds is how to make any change associated with increasing CO2 look like a dire catastrophe. So now the hymn sheet is “trees are bad, grass is good”. But hang on – when ecologists talk about deforestation in Brazil etc and conversion of forest to grass-based agriculture, then it was “trees are good, grass is bad”.
Where have I read something like that before?
O yes – it was in Animal Farm, by George Orwell. The pigs were taught to sing “two feet bad, four feet good”. But then Napolean and the ruling pigs learned to walk bipedally themselves, so the correct song was changed to “four feet bad, two feet good”.
So lets all sing along now: “carbon dioxide bad, extinction of plants and all life on earth GOOD” (not all that singable I guess…)

MattN

So….this is bad, right?

A Lovell

I remember a TV programme presented by Archbishop Attenborough about elephants changing the landscape from savannah to forest over generations. The following is from the WWF website.
“Elephants directly influence forest composition and density, and can alter the broader landscape. In tropical forests, elephants create clearings and gaps in the canopy that encourage
tree regeneration. In the savannas, they can reduce bush cover to create an environment favorable to a mix of browsing and grazing animals.”
Has elephant behaviour been taken into consideration in this study?

Huub Bakker

Elephants love grass and will knock down Acacia trees if they become too plentiful. They are one of the reasons that the savannah survives. Nature’s bulldozers indeed.

Paul Coppin

Henceforth, the Holocene shall be known as the Hollowcene, wherein it has been shown, and repeatedly replicated, that in the 21st century, the great “explosion” of CO2 is strongly and positively correlated with the explosion of empty PhDs, devoid of skills, intellect and acumen, wrapped as they are with all the glitter akin to galaxies, but like the galaxies, comprised of an inner core from which no useful energy emanates.

Sean

If you do not want the trees, just cut them down. People will welcome the fire wood, and timber.
Humans have mastered slash and burn thousands of yeras ago.

David L. Hagen

Some figures available with the Abstract for:
Steven I. Higgins and Simon Scheiter (2012).Atmospheric CO2 forces abrupt vegetation shifts locally, but not global. Nature Climate Change, DOI: 10.1038/nature11238

SasjaL

Steve Keohane on July 2, 2012 @ 7:54 am said:

Mars! Where else …?
Isn’t the acacia eaten by the tallest animal on the savannah …?
Wasn’t the Sahara a green, really green region 10 000 years ago …?
The studie is old news …!

re: “Experimental studies have generally shown that plants do not show a large response to CO2 fertilization.”
Does Higgins source that assertion? Because it would appear to be directly contradicted by the Science magazine article discussed here just a few days ago (Susanne von Caemmerer, W. Paul Quick, and Robert T. Furbank (2012). The Development of C4 Rice: Current Progress and Future Challenges. Science 336 (6089): 1671-1672.)
################
look at the charts and see how the effect is variety dependent.

Joachim Seifert

This must be a Frankfurt lie…. please see the “inconvenient truth-film”
of Al Gore, showing dried out, ripped and broken soil patches all over
to the horizon….and LESS vegetation.. This is the truth and also
“inconvenient”…..
someone did not learn from Al, who knows everything better on climate….
JS..

Myron Mesecke

Jeff says:
July 2, 2012 at 7:33 am
Hopefully we are equally skeptical of models that promise good news a century from now
All we know so far is that this is a study. Did they use computer models for this study? When we find this out then we can decide if we need to be skeptical.

“Experimental studies have generally shown that plants do not show a large response to CO2 fertilization” Which studies might these be? The folks over at CO2science.org hav catalogued an impressive array of studies demonstrating large responses over a wide variety of plants, including (in fact mainly considering) commercial varieties.

R. Craigen

“Experimental studies have generally shown that plants do not show a large response to CO2 fertilization” Which studies might these be? The folks over at CO2science.org hav catalogued an impressive array of studies demonstrating large responses over a wide variety of plants, including (in fact mainly considering) commercial varieties.

Silver Ralph

We are also seeing a shift in the N.H. jet streams, which are up to 500km further south in both summer and winter.
This is not only delivering much colder weather to northern Europe, it is also greening North Africa and sending the Sahara further south (hence the drought in the Saheel).

Jim

Total bunkum. CO2 went from 0.03% of the atmosphere to 0.04% of the atmosphere. This isn’t enough to have any significant effect on temperature, and it certainly isn’t going to have any significant effect on plant growth. It might have a minimal effect on growth rates, but it’s not going to change grasslands into tropical rain forests. Sorry this doesn’t pass the smell test, Anthony.

Jim

@R. Craigen: CO2science.org is no better of a source than pro-AGW sites. It’s an activist site too, and so not interested in real science. It’s just advocated the opposite view point. There is NO evidence that a tiny, almost immeasurably small change in a trace gas can effect global temperature or global flora. Come on, think about it! The concentration of CO2 in the atmosphere has increased less than one one-hundredth of a percent since 1900. Maybe if CO2 suddenly made up say 1% of the atmosphere, it might be believeable.

Justthinkin

eqibno asks….My question is: Will the Greens cut down the offending trees in the meantime to give the poor old grass a chance?
Why not?? They all ready burn down African villages and the surrounding forests to plant crap for their bio fuels??? (which blends well with the UN’s Agenda 21)
But not to worry. I have it on good authority(same sources Higgins uses) that it is actually just astroturf.

Jim says:
“CO2 went from 0.03% of the atmosphere to 0.04% of the atmosphere. This isn’t enough to have any significant effect on temperature, and it certainly isn’t going to have any significant effect on plant growth.”
Jim, take a look at these links. They show conclusively that a rise in CO2 results in more rapid plant growth:
click1
click2
click3
click4
click5
click6
CO2 has been much higher in the geologic past, when the biosphere teemed with life. The biosphere is currently starved of CO2, thus even a small increase has significant results. More CO2 is better. There is no downside with either current or projected concentrations. It’s all good.
You are right about the lack of any measurable effect CO2 has on global temperatures:
http://members.shaw.ca/sch25/FOS/GlobalTroposphereTemperaturesAverage.jpg

CATASTROPHIC regime change??
Why is it that ANY change in the natural environment is immediately labeled “catastrophic” based upon nothing other than some biologists idea of what is ‘supposed to be’ based upon what they saw on Mutual of Omaha’s Wild Kingdom as a child?. Apparently they have all forgotten that a few shakes of an aeon’s tail ago all of Africa’s savannahs were climaxed tropical rainforests, the ones where our proto-hominid ancestors used to live – up in the trees. The consequence of the ‘catastrophe’ of that particular tropical biome drying up was – us! – and all of those lovely grazing ungulates [who may have to graze a little harder to keep their grasslands open].
Now while I am perfectly willing to entertain the notion that increased CO2 fertilization will indeed lead to regime changes away from open grasslands to forests – we’ll see what happens. I seriously doubt though, that we will see the sudden disappearance of the grasslands and their grazing herds, unless we get rid of all of the grazing ungulates FIRST. It is instructive to look at what happened the North American grasslands after the bison was eliminated [largely eliminated]. The bison kept the great prairies, prairies, against the natural tendency towards forestation.
For all in all, I have a hard time imagining a trend towards forestation as anything other than a large net benefit for Africa, and the Earth as a whole.
W^3

Tim Clark

“According to leaf-level physiological models based on this mechanism, a doubling of the CO2 concentration from 350 to 700 p.p.m. and a 2–5 °C increase in temperature will favour C3 over C4 photosynthetic types. The implication is that, at the leaf level, the impacts of predicted CO2 changes overwhelm the impacts of predicted temperature changes.”
Epic physiological FAIL:
It depends on the absolute temp. The C-3 carbon capture enzyme Ribulose Bisphosphate Carboxylase has a much lower PKA above about 88F and actually respires above about 92F species dependent).The C-4 Phospho-enol-pyruvate Carboxylase functions with a lower dropoff up to about 96F (species dependent).
“This plot reveals that at high CO2 concentrations, C4-dominated states become more likely at sites with low rainfall (less than 250 mm), which explains why the model predicts that grasslands replace deserts (Fig. 1a). This interpretation is consistent with the theory that the water use efficiency of vegetation increases with atmospheric CO2 concentrations. At the high end of the rainfall gradient (Fig. 2a), the shift to C3-dominated states is both forced and catalysed by atmospheric CO2.”
Reasonable, considering C-4 plants have a higher Water use Efficiency on average.
Oh no! Looks like another hockey stick. Is it precipitation that causes the growth, or temperature or CO2?
“Our findings that shifts from C4-dominated to C3-dominated ecosystems are to be expected in the savanna complex are consistent with empirical observations, “with chamber experiments on the response of savanna trees” and C4 grasses to atmospheric CO2 concentration, and with leaf physiological models.”
They didn’t test trees, they tested leaves.
So, in summation, if all these variables favor C-3 plants, they will grow.
Go figure.

Rhys Jaggar

A classic example of the ‘law of unexpected outcomes’.
Well, maybe it’s not unexpected to people who really understand savannahs, but I’m sure it would be unexpected to computer modellers who in the main have little understanding of ecosystem biology.

Gerry Parker

Which implies the desertification of Africa is over? Which would reduce the wind blown Sahara dust from killing the reefs in the Caribbean basin. Both of which could be interpretted as good news. But wait….

Gerry Parker

And reducing the incidence of human asthma…

DesertYote

During the Roman Warm, much of what is now open savannas, was closed savannas or forest. The savanna is just another part of “The Circle of Life”.

Gerry Parker says:
July 2, 2012 at 12:02 pm
Which implies the desertification of Africa is over?
////////////////////////////////////////////////////////////////////////////////
Southern Sahel has been re-greening (don’t like the word – alternative anyone?!) for a few years now, I believe
Yeah – google of southern sahel regreening confirms this

Jimbo

The vegetation shifts that the Higgins and Scheiter study projects are an example of what some theorists call catastrophic regime shifts. Such catastrophic regime shifts can be triggered by small changes in the factors that regulate the system.

This is an example of Catastrophic Anthropogenic Regional Greening. 😉 No good ever comes from carbon dioxide. It’s all bad no matter how you look at it. Less green = bad. More green = bad. More trees = bad. Fewer trees = bad. It’s all BAD.

belvedere

Wow.. this shows how powerfull of a system our planet earth is…
*taking my hat off*

gringo jay

Caveat to bear in mind is that depending on the type of tree and the local properties that soil entails there is a side effect to increased % CO2 in that tree canopy. This is not even taking into account seasonal soil moisture and the type of preference of every tree there.
The photosynthesizing period of the tree is when the extra CO2 furnished Carbon can lead to more tree root mass; and the result may start to show up in some types that same day and in others after a delay of almost a month. So a seasonally adjusted rhythm of canopy is laid over this dynamic if tree’s leaves are no longer green (yellow) or many of canopy leaves have fallen.
The subtle factor is that all the above ground CO2 induced tree growth is also increasing the tree root surface (due to more available Carbon building block molecules).
However, during the daytime tree’s photosynthesizing actually results in all that extra below ground surface area of tree roots undergoing a process of increased soil respiration. Which means the available local soil moisture is wicked toward the root & proportionately more “water” evaporation occurs below that tree canopy enjoying extra CO2.
So, the result is under that CO2 enriched tree relatively less moisture is in that soil and then the savanna (grass) under that canopy will have to become more tolerant of lower soil moisture – or die back it’s own bio-mass so the grass can get by despite greater degree of soil respiration.

@ Jim:
“Total bunkum. CO2 went from 0.03% of the atmosphere to 0.04% of the atmosphere. This isn’t enough to have any significant effect on temperature, and it certainly isn’t going to have any significant effect on plant growth. It might have a minimal effect on growth rates, but it’s not going to change grasslands into tropical rain forests. Sorry this doesn’t pass the smell test, Anthony.”
You may be right, Jim, but isn’t an increase from .03% to .04% a double digit increase? — something on the order of 20-30%. If I’m understanding this correctly, that would seem possibly quite significant enough to have a measurable impact on plant growth. It all depends how much of a limiting factor Co2 was given the the other constraints of the plant’s environmental system. If Co2 was the limiting factor, small amounts could have large effects — or, at least, I would want to talk to a real expert before saying that the effects are necessarily small.