Intact Amazon forests show possible signs of global warming impact

mongabay.com
June 04, 2014



Fragmentation in Rondonia, Brazil
Fragmentation in Rondonia, Brazil. Courtesy of Google Earth

Climate change may be taking a hidden toll on intact rainforests in the heart of the Amazon, finds a new study based on 35 years of observations.

The research, published in the journal Ecology, focused on the ecological impacts of fragmentation but unexpectedly found changes in the control forests. These shifts, which included faster growth and death rates of trees, increased biomass accumulation, and proliferation in vines, may be linked to rising carbon dioxide concentrations in the atmosphere, according to George Mason University's Thomas Lovejoy, who initiated the study in the late 1970's.

“These changes might be driven by increasing carbon dioxide in the atmosphere,” said Lovejoy in a statement. “Plants use carbon dioxide for photosynthesis and when it increases, the forest evidently becomes more unstable and dynamic, as long as the soils have enough nutrients.”

The findings, which are consistent with other research in the region, lend further evidence to the argument that the world's largest rainforest is under threat from both land use change and global warming.

“It’s like a boxer getting hit by a flurry of punches,” said lead author William Laurance of James Cook University. “Humans continue to dump billions of tons of greenhouse gases into the atmosphere every year, and it’s evidently affecting even the remotest forests on Earth.”


Intact forest in the heart of the Amazon

Meanwhile fragmented forests are even more vulnerable.

“Lots of trees have died while vines, which favor disturbed forests, proliferate rapidly,” said co-author Jose Luis Camargo of Brazil’s National Institute for Amazonian Research.

Other studies have show that those changes leave fragmented forests more prone to die-off and fire.

The net result is the Amazon rainforest may become less stable as CO2 levels and disturbance continue to rise.

“A big implication is that it’s going to be harder to predict future changes to ecosystems if they’re being affected by several environmental drivers,” said Lovejoy.

It also complicates further research efforts, according to the authors.

"Researchers should be aware of the potentially confounding effects of large-scale environmental changes, and if possible should design careful experiments to identify and measure their effects. In these settings, there will rarely be true experimental controls—because, by their very nature, large-scale changes are occurring virtually everywhere. It is not inconceivable that such drivers are affecting most terrestrial ecosystems on Earth, whether impacted by anthropogenic land-use changes or not."

CITATION: William F. Laurance et al. (2014) Apparent environmental synergism drives the dynamics of Amazonian forest fragments. Ecology http://dx.doi.org/10.1890/14-0330.1












AUTHOR: Rhett Butler founded Mongabay in 1999. He currently serves as president, head writer, and chief editor.





Related articles

Logging, fires take a hidden toll on Amazon rainforest

(05/28/2014) Selective logging and small sub-canopy fires are degrading vast areas of rainforest across the Brazilian Amazon, contributing to largely hidden carbon emissions, argues a study published today in Global Change Biology. The research found stark differences in carbon storage between primary forests, selectively logged forests, logged and burned forests, and regrowing or secondary forests.


Rainforests on fire: climate change is pushing the Amazon over the edge

(04/18/2014) From 1999-2010, nearly three percent of the Amazon rainforest burned, and climate forecasts indicate dry conditions conducive to fire will only become more commonplace in the future. A new study indicates that rainforests are more vulnerable to fire than previously thought, and it warns the current combination of climate change and deforestation may be pushing Amazon forests past the breaking point.


Indigenous tribes say effects of climate change already felt in Amazon rainforest

(04/30/2013) Tribal groups in Earth's largest rainforest are already being affected by shifts wrought by climate change, reports a paper published last week in the British journal Philosophical Transactions of the Royal Society B. The paper, which is based on a collection of interviews conducted with indigenous leaders in the Brazilian Amazon, says that native populations are reporting shifts in precipitation patterns, humidity, river levels, temperature, and fire and agricultural cycles. These shifts, measured against celestial timing used by indigenous groups, are affecting traditional ways of life that date back thousands of years.


Will Amazon species lose the climate change race?

(02/14/2013) Deforestation could increase the risk of biodiversity loss in the Amazon by forcing species to migrate further in order to remain at equilibrium with changing climates, says new research. "As migration models are made more realistic through the inclusion of multiple climatic, biotic, abiotic and human factors, the predicted distances between current and future climate analogues invariably increases," Kenneth Feeley, lead author of the paper published in Global Change Biology, told mongabay.com.


Amazon rainforest failing to recover after droughts

(12/24/2012) The impact of a major drought in the Amazon rainforest in 2005 persisted far longer than previously believed, raising questions about the world's largest tropical forest to cope with the expected impacts of climate change, reports a new study published in the journal Proceedings of the National Academy of Sciences.


Advanced technology reveals massive tree die-off in remote, unexplored parts of the Amazon

(12/12/2012) Severe drought conditions in 2010 appear to have substantially increased tree mortality in the Western Amazon, a region thought largely immune from the worst effects of changes occurring in other parts of the world's largest rainforest, reported research presented last week at the fall meeting of the American Geophysical Union (AGU). The findings suggest that the Amazon may face higher-the-expected vulnerability to climate change, potentially undercutting its ability to help mitigate greenhouse gas emissions by absorbing carbon dioxide through faster growth.


Scientists slam Telegraph blogger's claims that climate change will be good for the Amazon

(07/12/2012) Recent blog posts on The Telegraph and the Register claiming that tropical rainforests like the Amazon are set to benefit from climate change are 'uninformed' and 'ridiculous' according to some of the world's most eminent tropical forest scientists. The posts, published Sunday and Monday by Tim Worstall, a Senior Fellow at London's Adam Smith Institute, asserted that a new Nature study indicates that 'climate change will mean new and larger tropical forests.' But some of the world's leading tropical forest experts took aim at Worstall's logic, noting the limitations of the study as well as the other factors that are endangering rainforests.


Climate change could increase fires, logging, and hunting in rainforests

(03/13/2012) The combined impacts of deforestation and climate change will bring a host of new troubles for the world's tropical rainforests argues a new study in Trends in Ecology and Evolution. Drying rainforests due to climate change could lead to previously inaccessible forests falling to loggers, burning in unprecedented fires, or being overexploited by hunters.


Deforestation, climate change threaten the ecological resilience of the Amazon rainforest

(01/19/2012) The combination of deforestation, forest degradation, and the effects of climate change are weakening the resilience of the Amazon rainforest ecosystem, potentially leading to loss of carbon storage and changes in rainfall patterns and river discharge, finds a comprehensive review published in the journal Nature.




CITATION:
mongabay.com (June 04, 2014).

Intact Amazon forests show possible signs of global warming impact.

http://news.mongabay.com/2014/0604-amazon-fragmentation-effects.html