Amazon rainforests could transition to savannah-like states in response to climate change, new study predicts

December 29, 2015 by Shreya Dasgupta, Mongaby
The massive Amazon forest is home to around 16,000 species of trees. Credit: Rhett Butler

By the end of this century, as climate continues to warm, dry seasons could become longer and more intense in the Amazon region. Droughts could become more commonplace. But the fate of the Amazon forest—home to around 300 billion trees, and crucial to the Earth's water and carbon cycle—in this drier future remains largely uncertain.

Some studies have predicted that the Amazon could suffer from a catastrophic die-back post 2050. Others have suggested that the region would mostly remain intact. Now, scientists say that the models used in these studies are flawed. The vast Amazonia is unlikely to respond to environmental changes in the same way, researchers say in a study published Monday in the Proceedings of the National Academy of Sciences. Instead, different parts of the Amazon will react differently and with varying intensities.

The problem with previously used climate-change models, researchers say, is that they treat the immensely diverse Amazon rainforest as a vast swath of monotonous green. By doing so, these models fail to capture the complexity of the Amazonian ecosystem.

To avoid these pitfalls, co-author Paul Moorcroft, an ecologist at Harvard University, and his colleagues, developed and used a new model called the Ecosystem Demography Biosphere model that allows scientists to track the response of individual trees to climate change. To predict how the Amazon could change in the future, the team combined field observations and remote sensing estimates to the model.

Anthropogenic activities like logging and mining, combined with longer dry seasons, could exacerbate transition of the Amazon rainforests to drier savannah-like states. Credit: Rhett Butler

The researchers did not find any evidence supporting previous studies that the Amazon forests would either collapse, or be unresponsive, in a warmer, drier climate in the future. Instead, their results suggest that the Amazon would show varied response to changes in the climate. And these changes will be gradual, the team found.

The model predicted, for example, that as dry seasons become longer, forests will lose more biomass. Gradually, high-biomass rainforests will transition to low-biomass dry forests and savannah-like states.

Parts of the Amazon that have a four-month long dry season could lose around 20 percent of their biomass with a two-month increase in dry season length, the model predicts. Drier forests, which have six-months long dry seasons, would respond more rapidly to changes in climate, losing around 29 percent of their biomass with a one-month increase in dry season length.

"Fire, logging, and other anthropogenic disturbances may, however, exacerbate these climate change-induced ecosystem transitions," the authors write in the paper.

The model also found that the soil type would influence how quickly the forests change. This is because the type of soil determines how much rainfall the soil holds, which in turn shapes the types of trees that grow in that soil.

For example, the model predicted that forests in soil with low clay content will be relatively unaffected by the change in climate regime. In contrast, forests in soils with high clay content are more likely to change more rapidly in response to longer and increased water stress.

To understand, and accurately predict, how a complex and diverse forest responds to changes in climate, it is important to consider how and soils affect the performance of individual trees, the authors write.

"As we have shown here, models that incorporate plant-level dynamics are able to characterize observed extant patterns of variation in the structure, composition, and dynamics of Amazonian ecosystems more accurately," the authors add, "and accounting for these patterns has important implications for the sensitivity and ecological resilience of Amazon forests to different levels of climatological perturbation."

Explore further: Risk of Amazon rainforest dieback is higher than IPCC projects, researchers say

More information: Naomi M. Levine et al. Ecosystem heterogeneity determines the ecological resilience of the Amazon to climate change, Proceedings of the National Academy of Sciences (2015). DOI: 10.1073/pnas.1511344112

Related Stories

Water forms common thread in diverse rainforest ecosystems

April 21, 2015

Rainforests, which are so critical to the earth's climate that they are frequently called the planet's lungs, are often thought of as a single collection of ecosystems. But researchers at Princeton University and other institutions ...

Recommended for you

19 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

OdinsAcolyte
1.5 / 5 (8) Dec 29, 2015
The Earth and life have survived much more drastic changes.
Adapt or die but stop the fear mongering.
It makes you seem weak, ignorant and needy.
Steve 200mph Cruiz
4.6 / 5 (12) Dec 29, 2015
Shut up odins, at no point has anyone said, "everyone gonna die!"
How are we supposed to adapt if we ignore all the consequences of our actions?
Strength and understanding come from predicting the future and having an edge over what happens.
A lot of things are going to change with the combination of climate change and the surface of the earth and its various chemistries being sold in incremental segments.

How are valuable (ecologically and financially) rainforest trees supposed to spread to more accommodating biomes, when they start growing on some poor farmers property?
It's all closing in, and its not in a way that has any historically comparable way, and that was ignoring industrial/plastic trash giving cancer to everything, and the extinction of key stone species worldwide
SamB
1 / 5 (5) Dec 31, 2015
This should make it easier for the farmers as they will not need to cut down large swaths of forests. Also, range wildlife will flourish and will eventually create a new tourist attraction in this area.
john_mathon
1 / 5 (5) Jan 02, 2016
There is no doubt in my mind we should study these things. The question is if articles need to be phrased such as "rainforests could transition to savannah" implying that if we continue putting out CO2 rainforests WILL convert to savannahs. In fact the probabilities are unknown and virtually anything could happen. On the other hand lots of things could happen and the rainforests could switch to savannah if we DON"T keep putting out CO2. We may be impacted by a meteor and a billion people die in 10 years. The sun may have a conniption and wipe out life on earth entirely. We may play with genetics and ... How do we rationally decide what to research? Looking at the number of articles in phy.org on stupid climate change hypothesis I'm guessing we're now spending half our entire research budget in the world on the impact of CO2 when it is likely that we will see no significant impact whatsoever from CO2.
john_mathon
1 / 5 (5) Jan 02, 2016
We have poured 57% of all the CO2 man has ever put into the atmosphere in the last 20 years. The net result is zilch. According to some the heat went into the deep ocean. Nobody knows if and when it would ever come out or if that is where the heat went from all that CO2. This could go on forever. Over the last 100+ years there has been 1.2C change however, there was no significant CO2 produced during the first 0.4C we got. Another 0.4C seems to have been manufactured through artfully prepared adjustmentrs to thousands of temperature stations selected almost as carefully as Mann selected his 12 trees to make the hockey stick. The remaining real 0.4C was probably half related to a natural PDO/AMO osciullation meaning CO2 contributed 0.2C. If we continue for another 80 years and pour exponentially more CO2 we might see another 0.2C. Not the biggest problem facing humanity.
Vietvet
4.3 / 5 (6) Jan 02, 2016
@jhon-m

A tip of the hat for your glorious display of willful ignorance.
gkam
2.3 / 5 (6) Jan 02, 2016
jmathon, look up "ten hottest years in history" and get back to us.

Thanks,

- The Rest of the World
john_mathon
3.7 / 5 (3) Jan 03, 2016
Hottest years since when? Since 2 years ago? What were you born in 2000? Do you think things never happened before you were born?
gkam
2 / 5 (4) Jan 03, 2016
You do not get the point: How many Humans were around in those times of extreme conditions?
HannesAlfven
1 / 5 (3) Jan 03, 2016
The real story here is that every single one of these studies costs an enormous amount of money, and that is money which could be spent addressing the controversies which whistleblowers like Dr. Gerald Pollack is claiming exist in every single scientific domain. The public should be pushing to spend this money on these challenges to textbook theory rather than these enormously speculative IPCC projections -- which are truthfully based upon so many assumptions that the conclusions cannot be relied upon as predictive.
john_mathon
1 / 5 (3) Jan 03, 2016
There was a dust bowl in the midwest in the 1930s, 1940s. Droughts, heat waves. We've seen them all before and NOTHING happening today hasn't happened a MILLION times before on this planet.
gkam
2 / 5 (4) Jan 03, 2016
You do not get it.

But you will.

Good luck to us all.
john_mathon
1 / 5 (1) Jan 06, 2016
Political driven science is no-science. It's not possible to do science when you are operating using illogical processes. Clearly there is not enough information to say we know anything about all this. This idea that "it's all settled" is the most preposterous anti-scientific statement I've ever seen. Even physicists know their theories are all wrong. They all have contradictions, problems that aren't understood that means all they can really say is that in our experience if you do X then Y will happen. In climate "science" they say this will happen, when it doesn't happen which it NEVER does they then go back reinterpret the data and after reanalysis say ah this is the real data. To my knowledge I have NEVER seen a climate prediction from this theory that matched the data UNTIL the data was reanalyzed. Often the reanlaysis uses entirely new mathematical tequniques nobody has used before. Check out the errors: it's astonishing: https://logiclogi.../2015/12
gkam
1 / 5 (4) Jan 06, 2016
john, your mind has set like concrete.

When the truth sinks in, it will break.

But we all have our errors - I actually enlisted and volunteered for the war of my generation. It was enough to keep me from being a "joiner" from there on.
TheGhostofOtto1923
4 / 5 (4) Jan 06, 2016
john, your mind has set like concrete.

When the truth sinks in, it will break.

But we all have our errors - I actually enlisted and volunteered for the war of my generation. It was enough to keep me from being a "joiner" from there on.
ImeImeImeImeIme the topic is always you, isnt it you psychopath?
gkam
1 / 5 (4) Jan 06, 2016
I am, in your posts.

Face it, I am your adolescent fixation, otto. You cannot resist me because of your own inadequacies. You tried the bully and other postures, but nothing works because I am a real person and you are just an anonymous sniper, cowering behind a phony name, like you bragged about.

I think it is time the government found out about you showing off the OBE, as if you earned one. You did not.
Uncle Ira
4.2 / 5 (5) Jan 06, 2016
I think it is time the government found out about you showing off the OBE, as if you earned one. You did not.


Well hooyeei Cher. Why you don't email them and tell them about it? I am sure it will do just as much good as all the silly emails and complaints you flood the front office with about taking back the physorg from the goobers.

Oh yeah, I almost forget. The ones about physorg aiding and abetting criminal liability were a hoot too Cher. The peoples in the front office thought those were good big fun too.

Oh yeah, I almost forget one more thing too. What kind of geniuses get together to make a bunch of sockpuppet accounts so they can lodge multiple complaints thinking they are looking like a bunch of different peoples instead of the three peoples they are? Those accounts come with individual computer id's EVEN when you use a proxy. You got to use DIFFERENT computers WITH your proxies.
TheGhostofOtto1923
4 / 5 (4) Jan 06, 2016
Yeah I expect a call from the queen any day now.

Bwahaahaaaaaaahaa
TheGhostofOtto1923
3.7 / 5 (3) Jan 06, 2016
Actually I did earn it. I got a handshake, a framed certificate, and a free meal at chipotles.

Bwahaahaaaaaa.

No it was Arthur treachers fish and chips.

Bwahaahaaaaaaahaa you sick old man.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.