The worst land grab in decades in the Brazilian Amazon is threatening the survival of isolated tribes that have no contact with the outside world, a rights group said Wednesday.
Ranchers and settlers in the remotest reaches of northwestern Brazil are voraciously cutting down rainforest to farm crops, encroaching on the ancestral lands of three uncontacted groups, said Survival International [Credit: AFP/Yasuyoshi Chiba]
Ranchers and settlers in the remotest reaches of northwestern Brazil are voraciously cutting down rainforest to farm crops, encroaching on the ancestral lands of three uncontacted groups, said Survival International.
The land grab is also threatening another tribe, the Uru Eu Wau Wau, or "Harpy Eagle" people, that has only limited contact with the outside world, said the London-based group.
Warning the groups face "annihilation," it accused local politicians in the state of Rondonia of backing the deforestation, even though the area is officially designated as an indigenous reserve and sits within a national park, Pacaas Novas.
Because isolated peoples' immune systems have never been exposed to the outside world's diseases, the land grab risks causing devastating outbreaks, Survival said.
"Around the world, industrialized society is stealing tribal lands in the pursuit of profit. What's happening in Brazil is simply a continuation of the invasion and genocide which characterized the European colonization of the Americas," said the group's director, Stephen Corry.
The organization quoted a letter the Harpy Eagle tribe sent to Brazilian police, in which they call the land grab "extremely serious."
"We are very worried because the invasions are close to our villages and putting the lives of women, old people, children and men at risk," said the letter.
Experts estimate between 50 and 90 percent of the populations of Brazil's isolated tribes were wiped out when the government initiated contact with them in the 1970s and 80s—official policy at the time.
Today, the government tries to avoid any contact with isolated peoples, in order to protect them.
Brazil is home to some 900,000 indigenous people from 305 different ethnic groups.
Even if people completely stopped converting tropical forests into farmland, the impacts of tropical deforestation would continue to be felt for many years to come. That's the conclusion of researchers reporting in the Cell Press journal >Current Biology who have used historical rates and patterns of tropical deforestation around the globe to estimate the resulting carbon emissions and species losses over time.
Modeled annual deforestation rates from 1950 to 2009 in five-year intervals [Credit: Rosa et al./Current Biology 2016]
The findings highlight the importance of accounting for the time lag between deforestation and its environmental impacts in meeting conservation goals.
"We show that even if deforestation had completely halted in 2010, time lags ensured there would still be a carbon emissions debt equivalent to five to ten years of global deforestation and an extinction debt of more than 140 bird, mammal, and amphibian forest-specific species, which, if paid, would increase the number of 20th century extinctions in these groups by 120 percent," says Isabel Rosa (@isamdr86) of the Imperial College of London. "Given the magnitude of these debts, commitments to reduce emissions and biodiversity loss are unlikely to be realized without specific actions that directly address this damaging environmental legacy."
It takes time after trees are cut down before the wood and other plant matter left at the site fully decay, releasing carbon into the atmosphere. The resulting loss of habitat also leads to species losses, but those effects also tend to occur gradually.
In the new study, Rosa and her colleagues used a spatially explicit land cover change model to reconstruct the annual rates and spatial patterns of tropical deforestation from 1950 to 2009 in the Amazon, Congo Basin, and Southeast Asia. Using those patterns, they estimated the resulting gross vegetation carbon emissions and species losses.
The findings show that current emissions and species extinctions are mostly tied to past actions. As a result, the researchers explain, changes in annual deforestation rates will initially have a smaller than expected effect on annual carbon emissions. For example, they write, a 30 percent reduction in deforestation rates as seen in the Brazilian Amazon between 2005 and 2010 only cut carbon emissions over the same time period by 10 percent.
The researchers also show that modern deforestation has left us with an estimated extinction debt of 144 vertebrate species found only in tropical forests. That's 20 percent more than the number of extinctions known to have occurred in vertebrate groups in more than a century.
"I expected an increase in both carbon emissions and species extinctions debts, but the magnitude of these debts was surprising," Rosa says.
The findings show that reaching national and global emissions targets will be even more challenging than anticipated.
"We need to do more if we want to avoid paying these debts, thus preventing further loss of species and carbon emissions," Rosa said. "We need to preserve existing habitats, but also restore forests that have been degraded. Allowing the forest to regrow on areas that have been deforested helps by creating 'new' suitable areas for species to survive in while allowing some of this excess carbon to be stored back in the new trees rather than emitted into the atmosphere."
Rosa says she'll continue to pursue the use of their models to support better policy and management decisions.
A new and more dangerous phase of impacts on the world's remaining tropical forests is emerging, threatening to simplify the world's most diverse ecosystem including mass species loss, according to new UCL-led research published today in Science.
Deforestation in Tesso Nilo, Sumatra [Credit: WWF]
The impact of humans on these areas has been increasing for millennia and today more than three-quarters of the world's remaining tropical forests have been degraded by human actions.
The scientists identified three prior phases of expanding impacts, the first when hunter-gatherers moved into tropical forests and the second following the emergence of tropical agriculture, some 6,000 years ago. Under both, the overall health of tropical forests was maintained.
Today, we live in the third phase, marked by much greater impacts, with distant decision-makers directing how land is used, including permanent intensive agriculture, often for soybeans or palm oil, frontier industrial logging for timber export, cross-continental species invasions, and early climate change impacts. The scientists term this phase the era of 'Global Integration', affecting even the most remote areas.
Lead author, tropical forest expert Dr Simon Lewis (UCL Geography and University of Leeds) said: "Earth has lost 100 million hectares of tropical forest over the last 30 years, mostly to agricultural developments. Few people think about how intertwined with tropical forests we all are. Many foodstuffs include palm oil which comes from once pristine Asian tropical forest, while remaining intact forests are buffering the rate of climate change by absorbing about a billion tonnes of carbon each year."
Current trends look set to intensify without major policy changes, as global food demand is projected to double, over 25 million kilometres of road are predicted to be built by 2050, and climate change intensifies, ushering in a new phase of human dominance of tropical forests.
Dr Lewis added: "I fear a global simplification of the world's most complex forests. Deforestation, logging and road building all create fragmented patches of forest. However, as the climate rapidly changes the plants and animals living in the rainforest will need to move to continue to live within their ecological tolerances. How will they move? This is a recipe for the mass extinction of tropical forest species this century.
"What is needed are unbroken areas of forest that link today's core tropical regions with forest areas about 4 degrees cooler, so as temperatures rise and rainfall patterns change species have a better chance of surviving rapid 21st century climate change. We need to bring conservation in line with the reality of climate change."
The authors note that while deforestation and degradation continue, more optimistically, logged forest retains many environmental benefits, and marginal agricultural lands are being abandoned, which can return back to forest.
Dr David Edwards (University of Sheffield), co-author of the study, said: "Much biodiversity still remains in selectively logged forests, and can recover in secondary forests that grow on abandoned farmland. There is abundant potential to incorporate these forests into global plans to make tropical biodiversity climate change ready.
"Despite their value for biodiversity, logged-over and old secondary forests are frequently threatened by conversion to species-poor agricultural plantations. We urgently need to protect these human-impacted forests, especially in regions such as Southeast Asia where almost nowhere is left undegraded."
A suite of policy measures can help tropical forests survive, including giving forest dwellers formal collective legal rights over their land, which previous studies have shown is one of the best ways of preserving forests. A study of 292 protected areas in Amazonia showed that indigenous reserves were the most effective at avoiding deforestation in high pressure areas.
Most of the financial benefits of logging and plantation agriculture, such as palm oil, flow out of the forests. Ensuring local people have collective long-term rights over their lands would mean that benefits flowing from forest lands accrue to local people. This can provide the beginnings of programs of 'development without destruction', tackling poverty while maintaining forests. This, the authors argue, provides human rights and conservation win-wins.
Dr Lewis added: "With long-term certainty of tenure people can plan, maintaining forests while investing in improving agricultural productivity without expanding into forested lands. Forest dwellers won't be perfect managers of forests, but they won't look for a quick profit and then move on, as big businesses often do.
"This is a pivotal year for the global environment. There are some good signs for the world's tropical forests, with the UN New York Declaration on Forests agreeing to not only halt deforestation, but also restore 150 million hectares of forest. However, there are ominous signs too, with the palm oil industry having driven the world's highest deforestation rates in South East Asia now gearing up to repeat this process across Africa.
"The Paris climate change talks in December are doubly important for forests and forest communities. The levels of emission cuts will be a critical factor in determining how many tropical forest plants and animals go extinct over the coming decades and centuries. The agreements on reducing deforestation, including durable finance, will be pivotal. The final test will be whether some funds for adaptation will include land-use planning to retain forest connectivity as the climate rapidly changes."
Source: University College London [August 24, 2015]
Research reveals that large areas of 'degraded' forest in Southeast Asia can play an important role in conserving mammal diversity.
Orangutan caught by motion-sensitive cameras [Credit: Oliver Wearn]
Mammals can be one of the hardest-hit groups by habitat loss, and a lot of research has been carried out to find the best ways to conserve mammal diversity.
Much of this research has focused on very large-scale changes in land use and the impacts this will have on overall mammal diversity. However, many important decisions about land use are made at much more local scales, for example at the level of individual landowners.
Now, in a detailed study led by Imperial College London that looked at mammal diversity across different small-scale landscapes in Borneo, researchers have identified previously logged forests as an overlooked source of refuge for mammals.
These 'selectively logged' forests, where only certain tree species are removed, are often considered to be degraded and are frequently cleared to make way for plantations. The new results, published in the >journal Ecological Applications, suggest they should be better protected.
The team recorded mammals using trap-and-release techniques and motion-sensing cameras over three years, creating an unprecedented 20,000 records of species in three land-use types: old-growth forest, logged forest and oil palm plantation. This is one of the most intensive studies of rainforest mammal diversity ever undertaken.
Leopard cat caught by motion-sensitive cameras [Credit: Oliver Wearn]
To their surprise, they found that mammal diversity for large mammals, like the clouded leopard and civets, was similar for both old-growth forests and logged forests. For small mammals, such as squirrels and rodents, the diversity was actually higher in logged forests.
Both sizes of mammals however suffered heavy losses of diversity in oil palm plantations. Most species discovered on the plantations likely spilled over from adjoining forests or riparian zones -- strips of forests surrounding rivers to reduce the chance of flooding.
Lead researcher Dr Oliver Wearn, who completed the research for his PhD in the Department of Life Sciences at Imperial, said that the surprise result that mammal diversity remains high in logged forests may be because of the way habitats are distributed.
"The logging process creates a greater variation in habitat types in a smaller area, from untouched areas on steep slopes to completely denuded areas of open grassland. Old-growth forests would likely have the same diversity if we looked at them on a much larger scale."
Bearded pig and young caught by motion-sensitive cameras [Credit: Oliver Wearn]
Dr Wearn also stresses that while a greater diversity is recorded now in these logged forests, it cannot yet be certain that this diversity will remain in the future as the knock-on effects of habitat loss take effect on mammals and other rainforest species.
He added: "What we can say from this study is that protecting those large areas of forest that have already been logged could help conserve mammal species better than preserving fragmented pockets of forests inside oil palm landscapes."
This study complements another recent study from Imperial, where researchers recommended rehabilitating logged forests as a way to prevent highly threatened species from becoming extinct.
"Where old growth forests remain, however, these are still the best habitats for mammals and other native species, and should be the absolute top priority for conservation," said Dr Wearn.
Author: Hayley Dunning | Source: Imperial College London [August 22, 2016]
Scientists from Wageningen UR and other institutes are proposing a new research model - the turnover model - as a way of answering the question why there are always so many plant species in tropical rainforests.
In their publication in New Phytologist magazine, the Dutch, British and Swiss scientists show that major evolutionary changes, such as the origin of large groups of species, occur with a reasonably constant frequency while the origin of new species is an explosive process.
Various models
Darwin’s contemporary Alfred Russel Wallace already argued that the Tropics are, in essence, a museum of biodiversity. As tropical climates are stable, Wallace suggested that species would gradually increase in number over longer time periods, the so-called museum model. More recently, however, it was suggested that the Pleistocene ice ages, and the impact thereof on the climate in the Tropics, resulted in recent explosions of speciation, the so-called cradle model.
Both models are supported by previous research into patterns of diversification in tropical plants. This research is performed by means of reconstructed ‘phylogenetic trees’; genealogical trees that show the interrelated descent of plant species. Where analyses of plant families focused on studying as many evolutionary lines as possible from the family, diversity was shown to increase gradually. For instance, the development of diversity in important tropical plant groups such as palm trees, the leguminous family and the soursop family, appear to follow the museum model. However, within these large plant families there are also plant genera that seem to follow the cradle model: so-called radiations in which many different species developed recently and over a short period of time.
Equatiing seems impossible
Equating these two models seems an impossible task. How can a large plant family that presents an explosive increase in the number of species diversify as an entire family following the museum model? The answer lies in analysing more species per family, and better modelling speciation over long periods in evolution via the computer.
In the turnover evolution model arise evolutionary lines with a more or less constant speed, while the individual species formation takes place abruptly and then happens explosively [Credit: Wageningen University]
Mahogany trees
Scientists from Wageningen UR, Kew (London) and Zürich compiled the largest amount of data so far for the Meliaceae , or mahogany family. This family mainly grows in the Tropics, and is known for valuable wood such as mahogany and Spanish cedar. Parts of the nuclear and chloroplast genome of approximately 35% of the species were sequenced; a technology in which all the building blocks of the DNA are mapped.
The analysis of evolutionary diversification showed that the diversity of larger groups, such as plant genera and families, does develop in accordance with the museum model, i.e., with a certain constant frequency in the origin of new branches. The scientists showed that, in addition to this ‘museum fundament’, the origin of individual species is an explosive process which occurs in accordance with the cradle model.
‘Young’ species
The research shows that the mahogany family developed approximately 68 million years ago. The circa 200 mahogany species that grow in the South American rainforests are largely the result of two explosions in speciation (radiations) that occurred independently in two evolutionary lines in the late Miocene epoch, which was less than 10 million years ago.
An interesting aspect of this explosive origin of large numbers of species within the mahogany family is that it involves two different groups within the family which independently evolved the same ecological adaptations, such as plant height and an adaptation of seeds to the same animal species that distribute them. In addition, the two groups show a similar speed of speciation. These abrupt increases in speciation speed occurred after the mahogany family had left its original habitat (tropical dry forests and seasonal forests) and colonised the rainforests, where they were faced with different climate conditions.
New model for evolution
The results of the study show that most mahogany species in the Tropics are relatively recent. It can be assumed that this also applies to other families. The authors propose a new model, the turnover model, in which the number of evolutionary lines increases with a more or less constant speed, while speciation occurs separately and in a more explosive way.
