Arquivo da tag: Floresta Amazônica

Newly discovered ancient Amazonian cities reveal how urban landscapes were built without harming nature (Science Alert)


A newly discovered network of “lost” ancient cities in the Amazon could provide a pivotal new insight into how ancient civilisations combined the construction of vast urban landscapes while living alongside nature. 

A team of international researchers, including Professor Jose Iriarte from the University of Exeter, has uncovered an array of intricate settlements in the Llanos de Mojos savannah-forest, Bolivia, that have laid hidden under the thick tree canopies for centuries. 

The cities, built by the Casarabe communities between 500-1400 AD, feature an unprecedented array of elaborate and intricate structures unlike any previously discovered in the region – including 5m high terraces covering 22 hectares – the equivalent of 30 football pitches – and 21m tall conical pyramids. 

Researchers also found a vast network of reservoirs, causeways and checkpoints, spanning several kilometres. 

The discovery, the researchers say, challenges the view of Amazonia as a historically “pristine” landscape, but was instead home to an early urbanism created and managed by indigenous populations for thousands of years. 

Crucially, researchers maintain that these cities were constructed and managed not at odds with nature, but alongside it – employing successful sustainable subsistence strategies that promoted conservationism and maintained the rich biodiversity of the surrounding landscape. 

The research, by Heiko Prümers, from the Deutsches Archäologisches Institut, Carla Jaimes Betancourt from the University of Bonn, José Iriarteand Mark Robinson from the University of Exeter, and Martin Schaichfrom the ArcTron 3D is published in the journal Nature

Professor Iriarte said: “We long suspected that the most complex pre-Columbian societies in the whole basin developed in this part of the Bolivian Amazon, but evidence is concealed under the forest canopy and is hard to visit in person. Our lidar system has revealed built terraces, straight causeways, enclosures with checkpoints, and water reservoirs. There are monumental structures are just a mile apart connected by 600 miles of canals long raised causeways connecting sites, reservoirs and lakes.   

“Lidar technology combined with extensive archaeological research reveals that indigenous people not only managed forested landscapes but also created urban landscapes, which can significantly contribute to perspectives on the conservation of the Amazon.   

“This region was one of the earliest occupied by humans in Amazonia, where people started to domesticate crops of global importance such as manioc and rice. But little is known about daily life and the early cities built during this period.” 

The team of experts used lidar technology – dubbed “lasers in the sky” – to peer through the tropical forest canopy and examine the sites, found in the savannah-forest of South West Amazonia. 

The research revealed key insights into the sheer magnitude and magnificence of the civic-ceremonial centres found buried in the forest.   

It showed that the core, central spread over several hectares, on top of which lay civic-ceremonial U-shaped structures, platform mounds and 21-m tall conical pyramids.  

The research team conservatively suggest that the scale of labour and planning to construct the settlements has no precedents in Amazonia and is instead comparable only with the Archaic states of the central Andes. 

Crucially, the research team insist this new discovery gives a pivotal new insight into how this ancient urbanism was carried out sustainably and embracing conservationism. 

At the same time the cities were built communities in the Llanos de Mojos transformed Amazonian seasonally flooded savannas, roughly the size of England, into productive agricultural and aquacultural landscapes.  

The study shows that the indigenous people not only managed forested landscapes, but also created urban landscapes in tandem – providing evidence of successful, sustainable subsistence strategies but also a previously undiscovered cultural-ecological heritage. 

Co-author, Dr Mark Robinson of the University of Exeter added: “These ancient cities were primary centres of a regional settlement network connected by still visible, straight causeways that radiate from these sites into the landscape for several kilometres. Access to the sites may have been restricted and controlled.  

“Our results put to rest arguments that western Amazonia was sparsely populated in pre-Hispanic times. The architectural layout of Casarabe culture large settlement sites indicates that the inhabitants of this region created a new social and public landscape.

“The scale, monumentality and labour involved in the construction of the civic-ceremonial architecture, water management infrastructure, and spatial extent of settlement dispersal, compare favourably to Andean cultures and are to a scale far beyond the sophisticated, interconnected settlements of Southern Amazonia.” 

Lidar reveals pre-Hispanic low-density urbanism in the Bolivian Amazon is published in Nature.

Pictures are available at

Forests follow unexpected—and surprisingly fast—paths to recovery (Anthropocene Magazine)

A new study found that carbon, nitrogen and soil density in cleared forests reached 90% of levels in untouched forests after 1 to 9 years. They key was leaving them alone.

By Warren Cornwall

February 16, 2022

Forests follow unexpected—and surprisingly fast—paths to recovery

A new study found that carbon, nitrogen and soil density in cleared forests reached 90% of levels in untouched forests after 1 to 9 years. They key was leaving them alone.

Jungles grow with such abandon they can obscure entire civilizations beneath roots and vines. That fertility could prove vital in the race to heal the scars of deforestation.

Tropical forests burned and cleared for farming and ranching in Central and South America and West Africa can bounce back in little more than a century, with some key features recovering in decades, according to new research.

While not a panacea for the destruction of ancient jungles across the globe, scientists say the findings suggest that if left to themselves, many of these places could regain the lush forests that are rich havens of biodiversity that also suck carbon from the atmosphere.

“These regrowing forests cover vast areas, and can contribute to local and global targets for ecosystem restoration,” said Lourens Poorter, an ecologist at Wageningen University in the Netherlands, who was part of the research.

Tropical jungles like the Amazon have been called the lungs of the planet for good reason. Fueled by abundant water, long growing seasons and fertile soils, forests ringing the planet’s equatorial middle can suck vast amounts of carbon from the atmosphere and provide a home for two-thirds of the world’s species.

But this richness has also made them a target for loggers, ranchers and farmers, ranging from small-time settlers to huge agricultural companies. Today, less than 50% of tropical rainforests are still standing.

As conservationists work to protect tropical landscapes, questions surround the fate of former forests turned into pasture and farmland. In the tropics in the Americas alone, an estimated 28% of forests are regrowing after being cleared. So a team of 90 scientists from research centers across the globe set out to see how these lands recovered.

Because such recovery can stretch for decades, the researchers sought to fast-forward through the process by simultaneously examining 77 sites at different stages of growth, including some old-growth forests. Places had been cleared and then abandoned for more than a century in some cases, and as little as a year in others. The locations covered both dry and wet forests, sprinkled across Central and South America and coastal west Africa.

At each location, the researchers measured a dozen key indicators of different kinds of ecological dynamics, including the makeup of the soil, leaf and stem size, how many plants fixed nitrogen in the soil, the total mass of all plants, the largest tree, and the diversity of plant species.

The forests followed unexpected paths to recovery. Scientists were surprised to see how quickly the soils recovered. Carbon, nitrogen and soil density reached 90% of levels in untouched forests after 1 to 9 years. Likewise, the functional composition of plants in the forests – the size of tree leaves, the density of wood in trees and presence of nitrogen-fixing trees – happened sooner than predicted, taking between 3 and 27 years to approach old-growth conditions, the researchers reported in Science.

The rapid soil recovery indicates that soil nutrients were buffered from slash-and-burn agriculture or enhanced by people as they burned foliage or planted nitrogen-fixing grasses, the scientists surmised. Most of the study plots were also not subject to high-intensity farming that can suck nutrients from the soil.

Some features of the forest flora also came back quickly. Fast-growing plants that first reclaim open ground gave way to more shade-tolerant plants relatively quickly, and plants returned by resprouting from seeds left by cleared plants.

“Nature will take care of it if we let it,” said Clemson University ecologist Saara DeWalt, who contributed data from forests in Panama that she has tracked since the 1990s. “Restoration of tropical forests should rely on natural regeneration. It’s the most efficient way to do it. It’s the most ecologically efficient. It’s the most economically efficient.”

Some kinds of recovery took much longer. The cleared areas took between 27 and 119 years for the total mass of greenery and the largest tree size to approach pristine conditions. It took 12 decades for the full panorama of species found in old-growth tropical forests to appear in re-growing forests.

Even that, however, is “notably fast” given the complexity of tropical forests, the scientists noted. The overall picture is one of resilience after farming or ranching, as long as it’s not too intensive and there is forest nearby to provide seeds. “If there’s no source for seeds, heavily degraded soils, and no way for animals to get there, that’s going to be a problem,” DeWalt said. “There will be times when planting will be necessary.”

Poorter, et. al. “Multidimensional tropical forest recovery.” Science. Dec. 9. 2021

Indigenous peoples by far the best guardians of forests – UN report (The Guardian)

Preserving Latin America’s forests is vital to fight the climate crisis and deforestation is lower in indigenous territories

Damian Carrington Environment editor @dpcarrington

Thu 25 Mar 2021 14.00 GMT Last modified on Thu 25 Mar 2021 16.44 GMT

A Waiapi boy climbs up a Geninapo tree to pick fruits to make body paint at the Waiapi indigenous reserve in Amapa state, Brazil.
A Waiapi boy climbs up a Geninapo tree to pick fruits to make body paint at the Waiapi indigenous reserve in Amapa state, Brazil. Photograph: AFP Contributor/AFP/Getty Images

The embattled indigenous peoples of Latin America are by far the best guardians of the regions’ forests, according to a UN report, with deforestation rates up to 50% lower in their territories than elsewhere.

Protecting the vast forests is vital to tackling the climate crisis and plummeting populations of wildlife, and the report found that recognising the rights of indigenous and tribal peoples to their land is one of the most cost-effective actions. The report also calls for the peoples to be paid for the environmental benefits their stewardship provides, and for funding for the revitalisation of their ancestral knowledge of living in harmony with nature.

However, the demand for beef, soy, timber, oil and minerals means the threats to indigenous peoples and their forest homes are rising. Hundreds of community leaders have been killed because of disputes over land in recent years and the Covid-19 pandemic has added to the dangers forest peoples face.

Sateré-Mawé men collect medicinal herbs to treat people showing Covid symptoms, in a rural area west of Manaus, Brazil.
Sateré-Mawé men collect medicinal herbs to treat people showing Covid symptoms, in a rural area west of Manaus, Brazil. Photograph: Ricardo Oliveira/AFP/Getty Images

Demands by indigenous peoples for their rights have become increasingly visible in recent years, the report said, but this has come with increasing persecution, racism, and assassinations. Supporting these peoples to protect the forests is particularly crucial now with scientists warning that the Amazon is nearing a tipping point where it switches from rainforest to savannah, risking the release of billions of tonnes of carbon into the atmosphere.

The report was produced by the UN Food and Agriculture Organization and the Fund for the Development of Indigenous Peoples of Latin America and the Caribbean (Filac), based on a review of more than 300 studies.

“Almost half of the intact forests in the Amazon basin are in indigenous territories and the evidence of their vital role in forest protection is crystal clear,” said the president of Filac, Myrna Cunningham, an indigenous woman from Nicaragua. “While the area of intact forest declined by only 5% between 2000 and 2016 in the region’s indigenous areas, in the non-indigenous areas it fell by 11%. This is why [indigenous peoples’] voice and vision should be taken into account in all global initiatives relating to climate change, biodiversity and forestry.”

“Indigenous peoples have a different concept of forests,” she said. “They are not seen as a place where you take out resources to increase your money – they are seen as a space where we live and that is given to us to protect for the next generations.”

Indigenous and tribal territories contain about a third of all the carbon stored in the forests of Latin America, said Julio Berdegué, the FAO’s Regional Representative: “These peoples are rich when it comes to culture, knowledge, and natural resources, but some of the poorest when it comes to incomes and access to services.” Supporting them would also help avoid new pandemics, he said, as these are most often the result of the destruction of nature.

Cattle graze on land recently burned and deforested by farmers near Novo Progresso, Pará state, Brazil.
Cattle graze on land recently burned and deforested by farmers near Novo Progresso, Pará state, Brazil. Photograph: André Penner/AP

“Even under siege from Covid-19 and a frightening rise in invasions from outsiders, we remain the ones who can stop the destruction of our forests and their biodiverse treasures,” said José Gregorio Diaz Mirabal, indigenous leader of an umbrella group, the Coordinator of the Indigenous Organizations of the Amazon Basin. He said the report’s evidence supports his call for climate funds to go directly to indigenous peoples and not governments vulnerable to corruption. Advertisement

The report found the best forest protection was provided by peoples with collective legal titles to their lands. A 12-year study in the Bolivian, Brazilian, and Colombian Amazon found deforestation rates in such territories were only one half to one-third of those in other similar forests. Even though indigenous territories cover 28% of the Amazon Basin, they only generated 2.6% of the region’s carbon emissions, the report said.

Indigenous peoples occupy 400m hectares of land in the region, but there is no legal recognition of their property rights in a third of this area. “While the impact of guaranteeing tenure security is great, the cost is very low,” the report said, needing less than $45 per hectare for the mapping, negotiation and legal work required.

The report said it would cost many times more to prevent carbon emissions from fossil fuel burning using carbon capture and storage technology on power plants. The granting of land rights to indigenous people has increased over the last 20 years, Cunningham said, but has slowed down in recent years.

Paying indigenous and tribal communities for the environmental services of their territories has reduced deforestation in countries including Ecuador, Mexico, and Peru. Berdegué said such programmes could attract hundreds of millions of dollars per year from international sources.

The need for protection is urgent, the report said, with annual deforestation rates in Brazil’s indigenous territories rising from 10,000 hectares in 2017 to 43,000 hectares in 2019. In January, indigenous leaders urged the international criminal court to investigate Brazil’s president, Jair Bolsonaro, over his dismantling of environmental policies and violations of indigenous rights.

Elsewhere, the area of large intact forests in indigenous territories has fallen between 2000 and 2016, with 59% lost in Paraguay, 42% in Nicaragua, 30% in Honduras and 20% in Bolivia. Mining and oil concessions now overlay almost a quarter of the land in Amazon basin indigenous and tribal territories, the report said.

Para estudioso do clima, “sorte” explica pandemia não começar pelo Brasil (ECOA/UOL)

Artigo original

Rodrigo Bertolotto De Ecoa, em São Paulo 14/04/2020 18h04

“A Amazônia tem a maior quantidade de microorganismos do mundo. E estamos perturbando o sistema o tempo todo, com populações urbanas se aproximando, desmatamento e comércio de animais silvestres. Então, talvez tenha sido sorte que a pandemia não tenha começado no Brasil”, disse Carlos Nobre, presidente do Painel Brasileiro de Mudanças Climáticas e pesquisador sênior do Instituto de Estudos Avançados da USP (Universidade de São Paulo).

O cientista Carlos Nobre, referência brasileira em estudos sobre aquecimento global e pesquisador do Instituto Nacional de Pesquisa Espacial (Inpe) - Reinaldo Canato/Folhapress
O cientista Carlos Nobre, referência brasileira em estudos sobre aquecimento global e pesquisador do Instituto Nacional de Pesquisa Espacial (Inpe) Imagem: Reinaldo Canato/Folhapress

Nobre participou nesta terça de um seminário “Covid-19 e Clima: Como Estão Conectados?” promovido pela Rede Brasil do Pacto Global da ONU (Organização das Nações Unidas) em parceria com Ecoa, que retransmitiu sua palestra, no formato webinar, ou seja, um seminário pela web.

“Pandemia mostra impacto do desequilíbrio do sistema na nossa vida”

Ele lembrou do caso da leishmaniose, endemia típica da Amazônia que tem como causador um protozoário e o vetor é o mosquito palha. A doença se espalhou pelo mundo, devido à aproximação dos homens dos ambientes silvestres, mas agora está controlada, tendo cura e remédio. O problema agora é outro por lá. “Agora, Manaus está entrando em colapso com o coronavírus, e a doença está chegando às aldeias. Temos que lembrar que os indígenas têm menos resistência imunológica a essas contaminações.”

Nobre também falou como a poluição debilita quem tem contado agora com o vírus surgido na China no final de 2019. “A poluição e o vírus atacam o sistema respiratório. Essa combinação é muito perversa”, afirmou o estudioso.

Ele recordou das queimadas na floresta amazônica em 2019, a que ponto isso afetou os ares até da região Sudeste do Brasil e como esse cenário pode se repetir agora em 2020, quando se está verificando novos recordes de desmatamento.

O ar de São Paulo e outras cidades está mais limpo com menos carros em circulação nesses dias de quarentena, mas, se as queimadas recomeçarem, esse cenário vai mudar e criar novas vulnerabilidades. No ano passado, os postos de saúde da Amazônia estavam cheios pela fumaça das queimadas. Agora estão com a Covid-19.

Aprendizados da crise

O cientista discutiu os vários pontos que aproximam o atual surto biológico com os problemas climáticos, sua especialidade.

“Dá para fazer um paralelo entre essas crises globais. Essa pandemia nos mostra o que pode acontecer quando há um desequilíbrio do sistema. Ela é um alerta e um guia para evitarmos grandes riscos, como os que as mudanças climáticas poderão trazer para a vida na Terra. Se a temperatura do planeta subir cinco graus, os humanos vão ter de viver confinados, como agora, porque em determinados horários todos os dias o termômetro vai estar além do limite fisiológico do corpo nas áreas tropicais como o Brasil.”

Nobre falou das lições que podem ficar desta crise global e das possíveis soluções quando o planeta sair das urgências do coronavírus. Para ele, um dos aprendizados é que a economia caminhe para a sustentabilidade.

“Os países europeus estão discutindo agora uma economia mais verde. E a China também está sinalizando nesse mesmo caminho. Se isso acontecer, o pêndulo mundial vai mudar, e o Brasil vai ter de ir atrás. Os EUA são contra, mas isso pode mudar se em janeiro de 2021 não estiver mais o Donald Trump na Casa Branca”, afirmou Nobre, projetando as dificuldades de reeleição do político republicano com a possível recessão provocada pelo afastamento social durante a crise.

O pesquisador também salientou que é importante mudar a matriz energética, e essa crise pode ser o momento de acelerar esse processo. “Precisamos eletrificar os transportes, e criar mais energia solar e eólica, diminuindo o consumo de combustíveis fósseis.”

Para ele, as mudanças climáticas vão trazer riscos maiores que os atuais com o coronavírus se não forem tomadas providências. “É uma catástrofe com um tempo e uma magnitude muito maior. Por isso, é difícil dimensionar. Mas a atual pandemia é uma amostra disso. E um risco maior também, afinal, todo o planeta vai ser afetado, não só o homem, como agora.”

Veja íntegra do seminário:

How the Amazon’s Cashews and Cacao Point to Cultivation by the Ancients (New York Times)

Scientists studying the Amazon rain forest are tangled in a debate of nature versus nurture.

Many ecologists tend to think that before Europeans arrived in the Americas, the vast wilderness was pristine and untouched by humans. But several archaeologists argue that ancient civilizations once thrived in its thickets and played a role in its development.

Now, researchers have found evidence that indigenous people may have domesticated and cultivated Amazonian plants and trees thousands of years ago, further supporting the idea that ancient humans helped shape the forest.

“Large areas of the Amazon are less pristine than we may think,” said Hans ter Steege, a tropical ecologist at the Naturalis Biodiversity Center in the Netherlands, and an author of a paper published in Science on Thursday. “The people who lived there before Columbus left serious footprints that still persist in the composition as we see today.”

He was one of more than a hundred researchers who found that domesticated tree and palm species — like cacao, cashews, the açaí palm, the Brazil nut and rubber — were five times more likely to dominate the modern Amazonian forest than nondomesticated plants.

Carolina Levis, a doctoral student at the National Institute for Amazonian Research in Brazil and Wageningen University and Research Center in the Netherlands, was the lead author on the study. She and her team looked at a database from the Amazon Tree Diversity Network containing 1,170 plots of forest. Most plots measured approximately 2.5 acres each and had previously been investigated on foot by ecologists who counted and identified the plant species in the plots. Ms. Levis then identified 85 domestic plants to analyze.

One way the team determined that a plant had been domesticated was a look at its fruit. They found, for example, some peach palms that bore fruit weighing 200 grams, or 0.44 pounds, when the fruit grown in the wild matured to about one gram. Several of the domesticated plants they identified are still grown by South Americans.

The harvesting of peach palm in the Amazon. Credit: Tinde van Andel 

Ms. Levis compared her list of 85 plants to another database of more than 3,000 archaeological sites, including ceramics, dirt mounds and rock paintings, dating back before the Spaniards and Portuguese arrived in the Americas 500 years ago. The domesticated plants flourished near the archaeological sites, far more so than nondomesticated ones.

“It’s the first time that we show these correlations between plant species in the forest today and archaeological finds,” she said.

The findings suggest that either the ancient civilizations grew and cultivated the plants, or that they purposely settled in areas that had plants they could eat and use. Ms. Levis said she suspected that people were domesticating the plants, although the study did not definitively pinpoint how settlements were chosen. In some plots, more than half of the plant life consisted of domesticated trees and palms.

Jennifer Watling, an archaeologist at the University of São Paulo, Brazil, who was not involved with the study, said in an email that “the large number of data points sampled by these authors gives good reason to believe that the distribution of domesticated species in many areas of Amazonia is strongly linked to the actions of pre-Columbian societies.”

But Crystal McMichael, a paleoecologist from the University of Amsterdam, said the database comparisons were not convincing. New direct evidence, like fossils of domesticated plants at the archaeological sites, would help advance such theories, she said. While the study shows a potential association between ancient people and modern forest composition, it does not preclude the possibility that the domesticated plant patterns occurred with more modern settlements, she said in an email.

Dr. ter Steege disagreed. The study “changed my view of the forest,” he said. “It’s not only the ecology or the environment that created this forest, but also the people who lived there before.”

Corte seletivo e fogo fazem Floresta Amazônica perder 54 milhões de toneladas de carbono por ano (Agência Fapesp)

JC e-mail 4973, de 16 de junho de 2014

A perda de carbono corresponde a 40% daquela causada pelo desmatamento total

Uma pesquisa conduzida por cientistas no Brasil e no Reino Unido quantificou o impacto causado na Floresta Amazônica por corte seletivo de árvores, destruição parcial pelo fogo e fragmentação decorrente de pastagens e plantações. Em conjunto, esses fatores podem estar subtraindo da floresta cerca de 54 milhões de toneladas de carbono por ano, lançados à atmosfera na forma de gases de efeito estufa. Esta perda de carbono corresponde a 40% daquela causada pelo desmatamento total.

O estudo, desenvolvido por 10 pesquisadores de 11 instituições do Brasil e do Reino Unido, foi publicado em maio na revista Global ChangeBiology.

“Os impactos da extração madeireira, do fogo e da fragmentação têm sido pouco percebidos, pois todos os esforços estão concentrados em evitar mais desmatamento. Essa postura deu grandes resultados na conservação da Amazônia brasileira, cuja taxa de desmatamento caiu em mais de 70% nos últimos 10 anos. No entanto, nosso estudo mostrou que esse outro tipo de degradação impacta severamente a floresta, com enormes quantidades de carbono antes armazenadas sendo perdidas para a atmosfera”, disse a brasileira Erika Berenguer, pesquisadora do Lancaster Environment Centre, da Lancaster University, no Reino Unido, primeira autora do estudo.

Segundo Joice Ferreira, pesquisadora da Empresa Brasileira de Pesquisa Agropecuária (Embrapa Amazônia Oriental), em Belém (PA), e segunda autora do estudo, um dos motivos dessa degradação ser menos percebida é a dificuldade de monitoramento. “As imagens de satélite permitem detectar com muito mais facilidade as áreas totalmente desmatadas”, afirmou.

“Nossa pesquisa combinou imagens de satélite com estudo de campo. Fizemos uma avaliação, pixel a pixel [cada pixel na imagem corresponde a uma área de 900 metros quadrados], sobre o que aconteceu nos últimos 20 anos. Na pesquisa de campo, estudamos 225 parcelas (de 3 mil metros quadrados cada) em duas grandes regiões, com 3 milhões de hectares [30 mil quilômetros quadrados], utilizadas como modelo para estimar o que ocorre no conjunto da Amazônia”, explicou Ferreira.

As imagens de satélite, comparadas de dois em dois anos, possibilitaram que os pesquisadores construíssem um grande painel da degradação da floresta ao longo da linha do tempo, em uma escala de 20 anos. Na pesquisa de campo foram avaliadas as cicatrizes de fogo, de exploração madeireira e outras agressões. A combinação das duas investigações resultou na estimativa de estoque de carbono que se tem hoje.

Duas regiões foram estudadas in loco: Santarém e Paragominas, na porção leste da Amazônia, ambas submetidas a fortes pressões de degradação. Nessas duas regiões foram investigadas as 225 áreas.

“Coletamos dados de mais de 70 mil árvores e de mais de 5 mil amostras de solo, madeira morta e outros componentes dos chamados estoques de carbono. Foi o maior estudo já realizado até o momento sobre a perda de carbono de florestas tropicais devido à extração de madeira e fogos acidentais”, disse Ferreira.

Segundo ela, a pesquisa contemplou quatro dos cinco compartimentos de carbono cujo estudo é recomendado pelo Painel Intergovernamental sobre Mudanças Climáticas (IPCC, na sigla em inglês), da Organização das Nações Unidas (ONU): biomassa acima do solo (plantas vivas), matéria orgânica morta, serapilheira (camada que mistura fragmentos de folhas, galhos e outros materiais orgânicos em decomposição) e solos (até 30 centímetros de profundidade). “Só não medimos o estoque de carbono nas raízes”, disse.

Para efeito de comparação, foram consideradas cinco categorias de florestas: primária (totalmente intacta); com exploração de madeira; queimada; com exploração de madeira e queimada; e secundária (aquela que foi completamente cortada e cresceu novamente).

As florestas que sofreram perturbação, por corte ou queimada, apresentaram de 18% a 57% menos carbono do que as florestas primárias. Uma área de floresta primária chegou a ter mais de 300 toneladas de carbono por hectare, enquanto as áreas de floresta queimada e explorada para madeira tiveram, no máximo, 200 toneladas por hectare, e, em média, menos de 100 toneladas de carbono por hectare.

Corte seletivo tradicional
O roteiro da degradação foi bem estabelecido pelos pesquisadores. O ponto de partida é, frequentemente, a extração de madeiras de alto valor comercial, como o mogno e o ipê; essas árvores são cortadas de forma seletiva, mas sua retirada impacta dezenas de árvores vizinhas.

Deflagrada a exploração, formam-se várias aberturas na cobertura vegetal, o que torna a floresta muito mais exposta ao sol e ao vento, e, portanto, muito mais seca e suscetível à propagação de fogos acidentais. O efeito é fortemente acentuado pela fragmentação da floresta em decorrência de pastagens e plantações.

A combinação dos efeitos pode, então, transformar a floresta em um mato denso, cheio de árvores e cipós de pequeno porte, mas com um estoque de carbono 40% menor do que o da floresta não perturbada.

“Existem, hoje, vários sistemas de corte seletivo, alguns um pouco menos impactantes do que outros. O sistema predominante, que foi aquele detectado em nosso estudo, associado ao diâmetro das árvores retiradas e à sua idade, pode subtrair da floresta uma enorme quantidade de carbono”, disse Plínio Barbosa de Camargo, diretor da Divisão de Funcionamento de Ecossistemas Tropicais do Centro de Energia Nuclear na Agricultura (Cena) da Universidade de São Paulo (USP) e membro da coordenação da área de Biologia da FAPESP, que também assinou o artigo publicado na Global ChangeBiology.

“Por mais que recomendemos no sentido contrário, na hora do manejo efetivo acabam sendo retiradas as árvores com diâmetros muito grandes, em menor quantidade. Em outra pesquisa, medimos a idade das árvores com carbono 14. Uma árvore cujo tronco apresente o diâmetro de um metro com certeza tem mais de 300 ou 400 anos. Não adianta retirar essa árvore e imaginar que ela possa ser substituída em 30, 40 ou 50 anos”, comentou Camargo.

A degradação em curso torna-se ainda mais preocupante no contexto da mudança climática global. “O próximo passo é entender melhor como essas florestas degradadas responderão a outras formas de distúrbios causados pelo homem, como períodos de seca mais severos e estações de chuva com maiores níveis de precipitação devido às mudanças climáticas”, afirmou o pesquisador britânico Jos Barlow, da Lancaster University, um dos coordenadores desse estudo e um dos responsáveis pelo Projeto Temático ECOFOR: Biodiversidade e funcionamento de ecossistemas em áreas alteradas pelo homem nas Florestas Amazônica e Atlântica.

Além dos pesquisadores já citados, assinaram também o artigo da Global ChangeBiologyToby Alan Gardner (Universityof Cambridge e Stockholm EnvironmentInstitute), Carlos Eduardo Cerri e Mariana Durigan (Escola Superior de Agricultura Luiz de Queiroz/USP), Luiz Eduardo Oliveira e Cruz de Aragão (Instituto Nacional de Pesquisas Espaciais e UniversityofExeter), Raimundo Cosme de Oliveira Junior (Embrapa Amazônia Oriental) e Ima Célia Guimarães Vieira (Museu Paraense Emílio Goeldi).

O artigo A large-scalefieldassessmentofcarbon stocks in human-modified tropical forests (doi: 10.1111/gcb.12627), de Erika Berenguer e outros, pode ser lido em

(Agência Fapesp)

Líder indígena brasileiro ganha prêmio ‘Herói da Floresta’ da ONU (G1;Globo Natureza)

JC e-mail 4703, de 11 de Abril de 2013.

Almir Suruí, de Rondônia, fez parceria com Google para monitorar floresta. Ele está na Turquia para receber o título internacional

Almir Suruí, líder indígena de Rondônia, é um dos vencedores do prêmio “Herói da Floresta” este ano. O título é concedido pelas Nações Unidas.

A cerimônia oficial de entrega estava prevista para acontecer na noite desta quarta-feira (10) em Istambul (hora local), onde acontece o Fórum sobre Florestas da ONU, que congrega representantes de 197 país.

Os outros quatro “Heróis da Floresta” deste ano são dos Estados Unidos, Ruanda, Tailândia e Turquia. Almir é o vencedor pela América Latina e o Caribe. Líder dos índios paiter suruí, Almir criou diferentes iniciativas para proteger e desenvolver a Terra Indígena Sete de Setembro, em Rondônia, onde mora.

O projeto mais conhecido usa a internet para valorizar a cultura de seu povo e combater o desmatamento ilegal. A partir de uma parceria com o Google e algumas ONGs, os suruí colocaram à disposição dos usuários da rede um “mapa cultural” que dá informações sobre sua cultura e história.

Eles também usam telefones celulares para tirar fotos da derrubada ilegal de floresta, determinando com o GPS o local exato do crime ambiental e enviando denúncias a autoridades competentes.

No ano passado, outros brasileiros já haviam sido premiados como “Heróis da Floresta” pela ONU: Paulo Adário, diretor do Greenpeace para a Amazônia, e o casal de ativistas José Cláudio Ribeiro e Maria do Espírito Santo, assassinado no Pará em maio de 2011, que foi nomeado como uma homenagem póstuma.