Amazon forests failing to keep up with climate change

A team of more than 100 scientists has assessed the impact of global warming on thousands of tree species across the Amazon to discover the winners and losers from 30 years of climate change. Their analysis found the effects of climate change are altering the rainforest’s composition of tree species but not quickly enough to keep up with the changing environment.

Amazon forests failing to keep up with climate change
Dying forest in Central Amazon, Brazil, 2016 [Credit: Adriane Esquivel Muelbert/University of Leeds]

The team, led by University of Leeds in collaboration with more than 30 institutions around the world, used long-term records from more than a hundred plots as part of the Amazon Forest Inventory Network (RAINFOR) to track the lives of individual trees across the Amazon region. Their results, published in Global Change Biology, found that since the 1980s, the effects of global environmental change – stronger droughts, increased temperatures and higher levels of carbon dioxide in the atmosphere – has slowly impacted specific tree species’ growth and mortality.
In particular, the study found the most moisture-loving tree species are dying more frequently than other species and those suited to drier climates were unable to replace them.

Lead author Dr Adriane Esquivel Muelbert, from the School of Geography at Leeds, said: “The ecosystem’s response is lagging behind the rate of climate change. The data showed us that the droughts that hit the Amazon basin in the last decades had serious consequences for the make-up of the forest, with higher mortality in tree species most vulnerable to droughts and not enough compensatory growth in species better equipped to survive drier conditions.”

Amazon forests failing to keep up with climate change
Measuring Amazon tree growth in forest plot, Peru (2009)
[Credit: Roel Brienen/University of Leeds]

The team also found that bigger trees – predominantly canopy species in the upper levels of the forests – are outcompeting smaller plants. The team’s observations confirms the belief that canopy species would be climate change “winners” as they benefit from increased carbon dioxide, which can allow them to grow more quickly. This further suggests that higher carbon dioxide concentrations also have a direct impact on rainforest composition and forest dynamics – the way forests grow, die and change.
In addition, the study shows that pioneer trees – trees that quickly spring up and grow in gaps left behind when trees die – are benefiting from the acceleration of forest dynamics.

Study co-author Oliver Phillips, Professor of Tropical Ecology at Leeds and founder of the RAINFOR network said: “The increase in some pioneer trees, such as the extremely fast growing Cecropia, is consistent with the observed changes in forest dynamics, which may also ultimately be driven by increased carbon dioxide levels.”

Amazon forests failing to keep up with climate change
Measuring big trees in Central Amazon, Brazil, 2016 [Credit: Adriane Esquivel Muelbert/University of Leeds]

Co-author Dr Kyle Dexter, from the University of Edinburgh, said: “The impact of climate change on forest communities has important consequences for rain forest biodiversity. The species most vulnerable to droughts are doubly at risk, as they are typically the ones restricted to fewer locations in the heart of the Amazon, which make them more likely to be extinct if this process continues.

“Our findings highlight the need for strict measures to protect existing intact rainforests. Deforestation for agriculture and livestock is known to intensify the droughts in this region, which is exacerbating the effects already being caused by global climate change.”

Source: University of Leeds [November 08, 2018]



Marine Protected Areas overlook a large fraction of biodiversity hotspots

Current marine protected areas (MPAs) leave almost three-quarters of ecologically and functionally important species unprotected, concludes a new performance assessment of the Finnish MPA network.

Marine Protected Areas overlook a large fraction of biodiversity hotspots
Credit: Thinkstock

Published in Frontiers in Marine Science, the study finds the MPAs were designated with little knowledge of local marine biodiversity — and that increasing existing networks by just 1% in ecologically most relevant areas could double conservation of the most important species. In addition to identifying areas of high conservation value, the methodology — which uses a unique new dataset of 140,000 samples — can also be used in ecosystem-based marine spatial planning and impact avoidance, including siting of wind energy infrastructure, aquaculture and other human activities.

Marine ecosystems are facing an unprecedented loss of biodiversity from habitat destruction, changing marine environments and increasing extraction of marine resources.

“This means now, more than ever, protected areas are crucial for sustaining marine ecosystems”, says Elina Virtanen, lead author of the study from the Finnish Environment Institute (SYKE), Finland.

Marine Protected Areas — which can encompass estuaries, seas and oceans — safeguard these natural resources from human activities. In Europe, EU member states use the EU Habitats Directive to designate protected areas based on a list of habitats and species deemed important for conservation.

In Finland, which has one of the most complex marine environments worldwide, around 10% of seas are currently protected. But the assessment of Finnish MPA efficiency reveals this has still left important parts of the ecosystem completely unprotected — with an average of only 27% of marine biodiversity currently protected.

So how has this happened?

“Establishment of these protected sites has relied on certain important habitats, such as lagoons, shallow bays and reefs, or the presence of seals or important bird areas, rather than knowledge of underwater species present or the ecological value of those areas,” explains Virtanen.

While the current Marine Protected Areas serve to protect many important habitats, they give too little consideration to underwater nature, especially functionally important species. But because extensive protective coverage has already been implemented in Finnish seas, clear evidence is required for any changes to be made to existing MPAs.

“It was therefore important to indicate the areas that are the most important hotspots for marine biodiversity,” says Virtanen.

The researchers had access to almost 140,000 recently collected samples of data on species and habitat distribution, as well as data on human pressures and the marine environment. These data were input into ecological distribution models to get a comprehensive view of the current marine environment.

These distribution models were then applied to a spatial prioritization technique called Zonation, which grades areas based on their ecological importance. This can be used to identify areas of high conservation value.

“We found that increasing the protected area from just 10% to 11% in the most biodiverse areas would double conservation of the most ecologically important species,” says Virtanen. “This means increased protection of rare and threatened species, functionally important species and fish reproduction areas.”

However, the researchers emphasize that increasing protected areas is not the only means for safeguarding the integrity of the marine ecosystem. Human activities threatening biodiversity can also be reallocated to areas of low biodiversity and conservation value using ecosystem-based marine spatial planning.

“We felt it is also important to highlight where sea usage can be allowed, such as the extraction of seabed materials, aquaculture, or wind energy,” says Virtanen.

This means a big win for marine protection, as well as a cost-effective MPA designation method that can keep policy-makers happy.

Provided sufficient data exist, the approach can be used globally to show that small but targeted changes can have massive effects on the efficiency of protected areas — and a major boost for sustainable use of the sea.

“There is a need to reassess current MPA boundaries to ensure they focus conservation efforts to the most valuable areas, and an increased emphasis on ecological efficiency is essential when designating or expanding MPAs,” says Virtanen. “This way we can ensure that Marine Protected Areas achieve global conservation objectives meaningfully and efficiently.”

Source: Frontiers [November 08, 2018]