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A large-scale deforestation experiment: Effects of patch area and isolation on Amazon birds

Smithsonian Libraries
As compared with extensive contiguous areas, small isolated habitat patches lack many species. Some species disappear after isolation; others are rarely found in any small patch, regardless of isolation. We used a 13-year data set of bird captures from a large landscape-manipulation experiment in a Brazilian Amazon forest to model the extinction-colonization dynamics of 55 species and tested basic predictions of island biogeography and metapopulation theory. From our models, we derived two metrics of species vulnerability to changes in isolation and patch area. We found a strong effect of area and a variable effect of isolation on the predicted patch occupancy by birds.

As Humpback Whales Migrate to Antarctica, One Straggler Washes Ashore in the Amazon

Smithsonian Magazine

Last Friday, researchers from the Brazilian conservation group Bicho D’Água spotted a group of vultures circling a mangrove on the remote island of Marajó. Upon arriving to take a closer look, the team made a startling discovery: As Matthew Haag writes for The New York Times, the scavengers were feasting on the carcass of a 26-foot-long humpback whale calf—an unusual sight given the fact that at this time of year, the whale should’ve been some 4,000 miles away in its seasonal Antarctic feeding grounds.

Speaking with Brazilian news site O Liberal, Bicho D’Água marine biologist Renata Emin offered a possible explanation for the calf’s presence, explaining, “We’re guessing that the creature was floating close to the shore [when] the tide, which has been pretty considerable over the past few days, picked it up and threw it inland.”

Still, the Independent’s Tim Wyatt points out, it remains unclear why the whale was so far inland, let alone roaming the northern Brazilian coast. Although humpback whales typically congregate around the country’s southern Bahia coast during the August through November breeding season, it’s rare for the creatures to journey north toward the mouth of the Amazon River.

Haag of The New York Times further notes that during the Southern Hemisphere’s summer, humpbacks migrate to the Antarctic’s warmer polar waters, abandoning the equatorial region of Brazil until the hemisphere’s winter months.

It’s likely the beached calf was separated from its mother during the whales’ mass migration south, Aamna Mohdin reports for the Guardian. Experts estimate the unlucky creature was about 12 months old—as the Epoch Times’ Louise Bevan writes, this is around the age when calves tend to depart from their mothers.

According to Bevan, the current leading hypothesis posits that the whale died at sea and was thrown about 50 feet inland by rough currents and high tides. Photographs of the scene offer few discernible clues to the calf’s cause of death, but as Bicho D’Água biologist Emin tells Brazilian news site G1, researchers are pursuing several lines of investigation: In addition to checking the calf for marks that could indicate whether it was trapped in a net or hit by a boat, the team is waiting on a necropsy report that should be ready within the next 10 days.

In the meantime, the Maritime Herald has raised at least one potential cause of death, suggesting that the calf died after ingesting plastics found in its marine environment. As EcoWatch reports, this is becoming an increasingly common occurrence across the world. Last November, a sperm whale washed up in Indonesia with nearly 13 pounds of plastic in its stomach.

Peter Evans, director of the British-based Sea Watch Foundation, shares an alternative theory with the Guardian’s Mohdin: “This calf probably got separated from its mother, maybe its mother had died, in the southern summer, and then wandered about trying to find food,” he says. “The idea that it was killed by ingesting plastic would need some evidence first to support it. It seems to me more likely that it simply starved to death.”

Unfortunately, the Telegraph’s Ryan Walker points out, it’s possible scavenging and decomposition that took place between the whale’s death and its discovery could hinder scientists from reaching definitive conclusions on its unusual fate.

Given the sheer size of the calf—despite the fact that it’s roughly half the size of an adult humpback, the whale still weighs a staggering 10 tons—and remote nature of its resting place, authorities plan on leaving the carcass largely intact. The creature’s skeleton, according to the Independent’s Wyatt, will be dismantled, preserved and sent to a natural history museum in the nearby city of Belem.

Rare Footage Shows the Last Surviving Member of an Uncontacted Amazon Tribe

Smithsonian Magazine

Since the 1990s, Brazilian officials have been tracking a man who is believed to be the lone surviving member of an isolated indigenous tribe. Though he is infrequently seen, the man leaves traces of his life in the Amazon jungle: a footprint here, a chopped tree there, holes for trapping prey, patches of planted fruit and vegetables.

Recently, as Sarah Dilorenzo of the Associated Press reports, officials released a short video of the unnamed man, offering a rare glimpse of one of the Brazil’s uncontacted tribespeople.

Brazil's National Indian Foundation, or Funai, recorded the brief video clip in 2011, but only made it public recently. Shot from a distance, the footage shows the man hacking at a tree with an axe. There is only one other known image of the man, captured by a documentary filmmaker in the 1990s, which shows his partially obscured face peering out from behind a cluster of thick foliage.

Anthropologists believe the man, who appears to be between 55 and 60 years old, has been living on his own in the jungles of Rondônia State for more than 20 years. The other members of his tribe were likely killed by ranchers, according to Ernesto Londoño of the New York Times. Funai has made several attempts to contact the man since, but he made it clear that he is not interested, even wounding an official with his arrow in 2005.

So Funai has been trying to help the man from a respectful distance. Officials have left him seeds and tools, and they are working to ensure that the area where he lives remains protected.

Altair Algayer, coordinator of the team that keeps track of the man, tells the AP’s Dilorenzo that officials wavered over releasing the tape because they could not ask the man for his permission. Ultimately, however, they decided to make the footage public, in the hope that it will reinforce the need to maintain legal protections of indigenous territories and call attention to the precarious existence of Brazil’s uncontacted peoples.

As logging, mining and farming industries push deeper into the Amazon, the more than 100 isolated tribes that live in Brazil have been facing acute threats to their existence. A major concern, according to the advocacy group Survival International, is disease. Isolated tribes are highly susceptible to flus and other infections transmitted by outsiders, and “it is not unusual” for 50 percent of a tribe to be wiped out by foreign illnesses within the first year of contact, Survival states.

Some indigenous groups have also been abandoning their land, driven away by noise and pollution. And some tribes have been deliberately attacked by ranchers and other industry workers vying for their land. Last year, for instance, 10 members of an uncontacted tribe were reportedly massacred by illegal gold miners in a remote region along the Jandiatuba River.

The Tanaru indigenous reserve, where the man in the video lives, is currently surrounded by ranchers and loggers, Slate reported in 2010, and Funai is struggling to keep the man and others like him safe. Budget cuts have forced the organization to shutter some of its monitoring stations, and Londoño of the Times reports that some of its outposts have been attacked by miners and loggers.

For now, however, the mysterious man in the video appears to be faring quite well. In May, the team that monitors him saw signs—footprints and a cut tree—indicating that he is still alive.

“He is the ultimate symbol of resilience and resistance,” Fiona Watson, research and advocacy director at Survival International, tells Londoño. “But we are witnessing genocide in real time. Once he’s gone, his people will have disappeared forever, along with all their history and knowledge.”

Researchers Travel to the Amazon to Find Out if Musical Taste is Hardwired

Smithsonian Magazine

It can often feel like there is something deep and universal about a collection of notes making up a chord or arranged into a beautiful melody. For some, music can crawl up the spine and evoke real shivers. Over the centuries, Western music has assumed its highly developed system of harmony and intervals was tapping into some grand truth innately recognized by all humans; after all, even Justin Bieber's music is based on mathematical ratios described by Pythagoras himself.

But new research shows that it may all be in the listener’s head, Sarah Kaplan reports The Washington Post. “People tend to assume that features of music that are present in Western music have some kind of fundamental importance, some biological basis,” Josh McDermott, an auditory neuroscientist at the Massachusetts Institute of Technology who traveled to the Amazon to study musical preference, tells Kaplan. “But this result suggests that isn't the case.”

A large chunk of the Earth’s population has been introduced to the Western musical tradition, meaning people grow up exposed to similar tone patterns and musical idioms. So McDermott decided to find a culture with no exposure to Western music to see if there was any biological or universal preference for Western harmonies.

According to a press release, anthropologist Ricardo Godoy invited McDermott to study members of the Tsimane. The indigenous people of some 12,000 farmers and foragers in the Bolivian Amazon have their own musical tradition, but it involves singing one line at a time and does not involve harmonies.

In 2011 and again in 2015, McDermott visited the Tsimane with Godoy. He tested 250 people playing them a series of notes, including consonant chords and dissonant chords, noting their preference for each, Ramin Skibba reports at Nature News.

The team also gave the same tests to Spanish-speaking villagers in a nearby town, people in the Bolivian capital of La Paz and groups of American musicians and non-musicians.

While they Tsimane could tell the difference between harmony and dissonance, they did not express a preference for one over the other. “What we found is the preference for consonance over dissonance varies dramatically across those five groups,” McDermott says in the press release. “In the Tsimane it’s undetectable, and in the two groups in Bolivia, there’s a statistically significant but small preference. In the American groups it’s quite a bit larger, and it’s bigger in the musicians than in the nonmusicians.”

The study concludes that musical preference comes from familiarity. "Rather than being an inevitable consequence of auditory system biology,” the researchers write in the study published in Nature, “it seems that the preferences exhibited by Western listeners for harmonic frequencies arise from exposure to Western music.”

In other words, if someone grows up with Bach and the Beatles, they learn to love the major scale. If they grew up in a family that listens to nothing but dissonant composers like Arnold Schoenberg and Balinese Gamelan music, then, well… they may need a separate study.

There is some evidence, however, that there could be some biological basis for the music we like and dislike. Skibba reports that McGill University neuroscientist Robert Zatorre points out that research on macaque monkeys show that they have neurons in their brain that respond differently to consonant and dissonant tones, something that may occur in the human brain as well. Still, he adds that humans are born with flexible brains and nervous systems, and are highly influenced by the environment they grow up in.

The effects of forest fragmentation on primates in the Brazilian Amazon

Smithsonian Libraries
Forest fragmentation, arising from deforestation, is a primary threat to primate conservation; however, species do not respond to fragmentation in the same manner. This dissertation examines how forest fragmentation affected 1) the distribution and persistence of six primate species and 2) the behavioral ecology of the northern bearded saki monkey (Chiropotes sagulatus). Research was conducted at the Biological Dynamics of Forest Fragments Project, located approximately 80 km north of Manaus, Amazonas, Brazil. Nine forest fragments and two areas of continuous forest were surveyed for primates from July-August 2003 and January 2005-June 2006. Fragment attributes (e.g., size, isolation, matrix attributes) were determined using satellite images. Although some species e.g., red howler monkey, Alouatta seniculus) were common in the forest patches, other species (e.g., black spider monkey, Ateles paniscus) were rarely present. Primate species richness was predicted by fragment size, distance to closest forest patch greater than 0.5 ha, and proportion of secondary growth in the matrix, but primate characteristics (e.g., body size, home range, degree of frugivory) did not predict species presence in the fragments. Although the bearded saki monkey is a medium-size, highly frugivorous monkey with a large home range, it was present in forest fragments less than 5% of the species’ home range size in continuous forest. Each bearded saki group was followed for three consecutive days during each data cycle. Every five minutes, the location and behavior of the monkeys were recorded. Monkeys in the small forest fragments had smaller group sizes, smaller day ranges, different travel and spatial patterns, and different behavioral activity budgets than monkeys in larger fragments and continuous forest. There was little overlap in diet between bearded saki groups, even when fruiting species were present in several study sites. The lack of successful births in the small forest fragments, discrepancies in diet between groups, avoidance of low-growth matrix, and avoidance of particular habitats raise concern for the population’s future. Forest fragment size and habitat type, as well as the presence and configuration of forest patches and secondary forest growth in the matrix, are important considerations when managing arboreal primate species in a fragmented landscape.

Forest fragmentation reduces seed dispersal of Duckeodendron cestroides, a Central Amazon endemic

Smithsonian Libraries
ABSTRACT Fragmentation that alters mutualistic relationships between plants and frugivorous animals may reduce the seed dispersal of trees. We examined the effects of forest fragmentation on the distributions of seeds and seedlings of a Central Amazon endemic tree, Duckeodendron cestroides. In the dry seasons of 2002-2004, seeds and first-year seedlings were counted within wedge-shaped transects centered around Duckeodendron adults in fragments and nearby continuous forests at the Biological Dynamics of Forest Fragmentation Project. Analyses showed that fragmentation reduced seed dispersal quantity and quality. The percent and distance of dispersed seeds were both twice as great in continuous forest as in fragments. The distances of each tree's five furthest dispersed seeds were three times greater in continuous forest than fragments. Over the 3-yr study, 20 times more seeds were dispersed more than 10 m from parent crowns in continuous forest than fragments. A regression analysis showed more dispersed seeds at all distances in continuous forest than fragments. Dispersal differences were strong in 2002 and 2004, years of large fruit crops, but weak or absent in 2003, when fruit production was low. As distance from parent crowns increased, the number of seedlings declined more rapidly in fragments than continuous forest. Distance-dependent mortality between the seed and seedling stages appeared to be more important in continuous forest than fragments. This research provides ample, indirect evidence demonstrating that forest fragmentation can result in the breakdown of a seed dispersal mutualism, potentially jeopardizing the reproduction of a rare, tropical tree. RESUMO Fragmentacao que altera as relacoes mutuais pode reduzir a dispersao de sementes. Aqui, apresentamos os resultados dos efeitos de fragmentacao da floresta Amazonica em dispersao e germinacao de sementes de Duckeodendron cestroides, uma arvore endemico ao Amazonia Central. A pesquisa foi feito no Projeto Dinamica Biologico de Fragmentos Florestais. Durante as estacoes secas de 2002-4, localizamos sementes e plantulas recem nascidas arredor de arvores maes em fragmentos e em mata continua. A porcentagem de sementes dispersas fora da copa e a distancia de dispersao foram duas vezes maior em mata continua do que em fragmentos. As distancias das cinco sementes dispersas mais distante de cada arvore foram tres vezes maior em mata continua. Durante os tres anos, 20 vezes mais sementes foram dispersas >10 m das arvores maes em mata continua. Os analises de regressao mostrarem menos sementes dispersas com aumento de distancia da arvore mae; as duas linhas, mata continua e fragmentos, foram diferentes, aquele de mata continua sempre acima e paralelo ao aquele de fragmentos. As diferencias foram fortes em 2002 e 2004, anos de muitos frutos, mas poucas o ausentes em 2003 quando teve menos frutos. O numero de plantulas diminuiu com distancia da arvore mae mais rapido em fragmentos do que em mata continua. Sobre a mortalidade, dependente de distancia, a porcentagem de sementes germinadas mostrou mais importancia na mata continua do que nos fragmentos. Nosso projeto apresenta evidencia indireta que a fragmentacao da floresta pode interromper o mutualismo de dispersao de sementes, possivelmente ameacando a reproducao duma arvore tropical, rara.

A DNA Search for the First Americans Links Amazon Groups to Indigenous Australians

Smithsonian Magazine

More than 15,000 years ago, humans began crossing a land bridge called Beringia that connected their native home in Eurasia to modern-day Alaska. Who knows what the journey entailed or what motivated them to leave, but once they arrived, they spread southward across the Americas.

The prevailing theory is that the first Americans arrived in a single wave, and all Native American populations today descend from this one group of adventurous founders. But now there’s a kink in that theory. The latest genetic analyses back up skeletal studies suggesting that some groups in the Amazon share a common ancestor with indigenous Australians and New Guineans. The find hints at the possibility that not one but two groups migrated across these continents to give rise to the first Americans.

“Our results suggest this working model that we had is not correct. There’s another early population that founded modern Native American populations,” says study coauthor David Reich, a geneticist at Harvard University.  

The origin of the first Americans has been hotly debated for decades, and the questions of how many migratory groups crossed the land bridge, as well as how people dispersed after the crossing, continue to spark controversy. In 2008, a team studying DNA from 10,800-year-old poop concluded that a group of ancient humans in Oregon has ancestral ties to modern Native Americans. And in 2014, genetic analysis linked a 12,000-year-old skeleton found in an underwater cave in Mexico to modern Native Americans.

Genetic studies have since connected both these ancient and modern humans to ancestral populations in Eurasia, adding to the case that a single migratory surge produced the first human settlers in the Americas. Aleutian Islanders are a notable exception. They descend from a smaller second influx of Eurasians 6,000 years ago that bear a stronger resemblance to modern populations, and some Canadian tribes have been linked to a third wave.

Reich’s group had also previously found genetic evidence for a single founding migration. But while sifting through genomes from cultures in Central and South America, Pontus Skoglund, a researcher in Reich’s lab, noticed that the Suruí and Karitiana people of the Amazon had stronger ties to indigenous groups in Australasia—Australians, New Guineans and Andaman Islanders—than to Eurasians.

Other analyses haven’t looked at Amazonian populations in depth, and genetic samples are hard to come by. So the Harvard lab teamed up with researchers in Brazil to collect more samples from Amazonian groups to investigate the matter. Together they scrutinized the genomes of 30 Native American groups in Central and South America. Using four statistical strategies, they compared the genomes to each other and to those of 197 populations from around the world. The signal persisted. Three Amazonian groups—Suruí, Karitiana and Xavante—all had more in common with Australasians than any group in Siberia. 

Researchers mapped similarities in genes, mutations and random pieces of DNA of Central and South American tribes with other groups. Warmer colors indicate the strongest affinities. (Pontus Skoglund, Harvard Medical School)

The DNA that links these groups had to come from somewhere. Because the groups have about as much in common with Australians as they do with New Guineans, the researchers think that they all share a common ancestor that lived tens of thousands of years ago in Asia but that doesn’t otherwise persist today. One branch of this family tree moved north to Siberia, while the other spread south to New Guinea and Australia. The northern branch likely migrated across the land bridge in a separate surge from the Eurasian founders. The researchers have dubbed this hypothetical second group “Population y” for ypykuéra, or “ancestor” in Tupi, a language spoken by the Suruí and Karitiana.

When exactly Population y arrived in the Americans remains unclear—before, after or simultaneously with the first wave of Eurasians are all possibilities. Reich and his colleagues suspect the line is fairly old, and at some point along the way, Population y probably mixed with the lineage of Eurasian settlers. Amazonian tribes remain isolated from many other South American groups, so that’s probably why the signal remains strong in their DNA.  

The results line up with studies of ancient skulls unearthed in Brazil and Colombia that bear stronger resemblance to those of Australasians than the skulls of other Native Americans. Based on the skeletal remains, some anthropologists had previously pointed to more than one founding group, but others had brushed off the similarities as a byproduct of these groups living and working in similar environments. Bones can only be measured and interpreted so many ways, while genes usually make a more concrete case.

“The problem so far was that there has never been strong genetic evidence to support this notion,” says Mark Hubbe, an anthropologist at Ohio State University who was not affiliated with the latest study.

But even genetic evidence is subject to skepticism and scrutiny. Cecil Lewis Jr., an anthropological geneticist at the University of Oklahoma, cautions that Amazonian groups are low on genetic diversity and are more susceptible to genetic drift. “This raises very serious questions about the role of chance … in creating this Australasian affinity,” he says.

Another group led by Eske Willerslev and Maanasa Raghavan at the University if Copenhagen reports in Science today that Native Americans descend from just one line that crossed the land bridge no earlier than 23,000 years ago. While they didn’t look at Amazonian groups in-depth, the team did find a weak link between Australasians and some South American populations, which they chalk up to gene flow from Eskimos. 

There’s just one problem: Evidence of Population y doesn’t persist in modern Eurasian groups, nor does it seem to show up in other Native Americans. If Aleutian Islanders or their ancestors had somehow mixed with an Australasian group up north or made their way south to the Amazon, they'd leave genetic clues along the way. “It’s not a clear alternative,” argues Reich. 

Both studies therefore suggest that the ancestry of the first Americans is a lot more complicated than scientists had envisioned. “There is a greater diversity of Native American founding populations than previously thought,” says Skoglund. “And these founding populations connect indigenous groups in far apart places of the world.”

Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites

Smithsonian Libraries
Aim The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Location Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1 Methods Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. Results The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%. Main conclusions Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space.

The Amazon Has Lost More Than Ten Million Football Fields of Forest in a Decade

Smithsonian Magazine

This year, I was on the judging panel for the Royal Statistical Society’s International Statistic of the Decade.

Much like Oxford English Dictionary’s “Word of the Year” competition, the international statistic is meant to capture the zeitgeist of this decade. The judging panel accepted nominations from the statistical community and the public at large for a statistic that shines a light on the decade’s most pressing issues.

On Dec. 23, we announced the winner: the 8.4 million soccer fields of land deforested in the Amazon over the past decade. That’s 24,000 square miles, or about 10.3 million American football fields.

(Chart: The Conversation, CC-BY-ND Source: Mongabay)

This statistic, while giving only a snapshot of the issue, provides insight into the dramatic change to this landscape over the last 10 years. Since 2010, mile upon mile of rainforest has been replaced with a wide range of commercial developments, including cattle ranching, logging and the palm oil industry.

This calculation by the committee is based on deforestation monitoring results from Brazil’s National Institute for Space Research, as well as FIFA’s regulations on soccer pitch dimensions.

Calculating the cost

There are a number of reasons why this deforestation matters – financial, environmental and social.

First of all, 20 million to 30 million people live in the Amazon rainforest and depend on it for survival. It’s also the home to thousands of species of plants and animals, many at risk of extinction.

Second, one-fifth of the world’s fresh water is in the Amazon Basin, supplying water to the world by releasing water vapor into the atmosphere that can travel thousands of miles. But unprecedented droughts have plagued Brazil this decade, attributed to the deforestation of the Amazon.

During the droughts, in Sao Paulo state, some farmers say they lost over one-third of their crops due to the water shortage. The government promised the coffee industry almost US$300 million to help with their losses.

Finally, the Amazon rainforest is responsible for storing over 180 billion tons of carbon alone. When trees are cleared or burned, that carbon is released back into the atmosphere. Studies show that the social cost of carbon emissions is about $417 per ton.

Finally, as a November 2018 study shows, the Amazon could generate over $8 billion each year if just left alone, from sustainable industries including nut farming and rubber, as well as the environmental effects.

Financial gain?

Some might argue that there has been a financial gain from deforestation and that it really isn’t a bad thing. Brazil’s president, Jair Bolsonaro, went so far as to say that saving the Amazon is an impediment to economic growth and that “where there is indigenous land, there is wealth underneath it.”

In an effort to be just as thoughtful in that sense, let’s take a look. Assume each acre of rainforest converted into farmland is worth about $1,000, which is about what U.S. farmers have paid to buy productive farmland in Brazil. Then, over the past decade, that farmland amounts to about $1 billion.

The deforested land mainly contributes to cattle raising for slaughter and sale. There are a little over 200 million cattle in Brazil. Assuming the two cows per acre, the extra land means a gain of about $20 billion for Brazil.

Chump change compared to the economic loss from deforestation. The farmers, commercial interest groups and others looking for cheap land all have a clear vested interest in deforestation going ahead, but any possible short-term gain is clearly outweighed by long-term loss.

Rebounding

Right now, every minute, over three football fields of Amazon rainforest are being lost.

What if someone wanted to replant the lost rainforest? Many charity organizations are raising money to do just that.

At the cost of over $2,000 per acre – and that is the cheapest I could find – it isn’t cheap, totaling over $30 billion to replace what the Amazon lost this decade.

Still, the studies that I’ve seen and my calculations suggest that trillions have been lost due to deforestation over the past decade alone.

Effects of forest disturbance on breeding habitat availability for two species of anurans in the Amazon

Smithsonian Libraries
Deforestation may cause substantial changes in community structure along freshwater habitat gradients. This study evaluated how biotic and abiotic factors affect the distribution and reproductive success of two frog species in Central Amazon. Ponds in continuous and disturbed forest were surveyed to determine the distribution of their associated aquatic predators and the production of newly metamorphosed frogs. The effect of each predator assemblage on tadpole survival was tested using mesocosms. Newly metamorphosed Osteocephalus taurinus occurred in short hydroperiod ponds in disturbed forest, where they had lower encounter frequencies with aquatic insects and no fish were detected. In contrast, newly metamorphosed Phyllomedusa tarsius were associated with longer hydroperiod ponds in continuous forest where fish and aquatic insects were prevalent. In the experimental study, O. taurinus tadpoles had lower survival rates than P. tarsius tadpoles, suggesting that O. taurinus is more vulnerable to fish and insect predators. These results are consistent with the pattern of metamorphic success along the hydroperiod gradient in the study area. If intact continuous forest continues to be harvested, species that require ponds with longer hydroperiods for successful metamorphosis would be prone to population declines.

Does the disturbance hypothesis explain the biomass increase in basin-wide Amazon forest plot data?

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Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change.

Foraging strategy and breeding constraints of Rhinophylla pumilio (Phyllostomidae) in the Amazon lowlands

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Bat diversity peaks in neotropical lowland forests, where 70-100 species may coexist in local assemblages. Understanding of factors that promote and maintain this diversity requires a thorough knowledge of the ecology and behavior of individual species. We studied the movement pattern, focusing on range size and foraging strategy, of the small frugivorous bat Rhinophylla pumilio (Phyllostomidae), with particular emphasis on constraints females have to deal with when rearing young. Because of the scattered distribution of its main food resource, infructescences of epiphytes, we hypothesized that R. pumilio should spend most of its flight time searching for food. Because its small body size incurs higher flight costs in comparison to larger fruit-eating bats, we further proposed that it should feed within small foraging areas that are close to each other and that commuting flights between foraging areas should be short and infrequent, resulting in small home ranges. Furthermore, we predicted that lactating females would change range size as well as activity budget by performing more search flights to increase food intake for milk production and more commuting flights to feed their young during nighttime. We radiotracked 9 females (4 nonreproductive, 4 lactating, and 1 subadult) and 2 males in the primary rain forest of Nouragues, French Guiana, for a total of 49 nights. Supporting our initial prediction, the foraging strategy of R. pumilio was mostly restricted to short (40- to 120-m) search flights in a single, rather small foraging area (3.5-14.1 ha). We observed a decrease in flight distances and size of foraging area, and an increase in total flight time throughout the night in lactating females that probably transported their young and nursed them in their foraging areas at night. Finally, we propose that the sensitivity of R. pumilio to forest fragmentation reported in previous studies may in part be caused by its foraging strategy because it consists mostly of short-distance search flights that make it difficult or impossible, particularly for lactating females, to regularly cross broad expanses of inhospitable matrix in fragmented forests. Fragmentation may therefore decrease breeding success and foster population decline in this species.

A narrative of travels on the Amazon and Rio Negro, with an account of the native tribes, and observations on the climate, geology, and natural history of the Amazon valley. By Alfred R. Wallace ..

Smithsonian Libraries
Also available online.

Spine title: Wallace's Travels.

Provenance: Class prize presentation bookplate to John F. Hornby, signed by A. Newland.

Dibner gift.

Elecresource

Contributions to an insect fauna of the Amazon Valley : Coleoptera--Longicornes : Part I. Lamiares / by H.W. Bates

Smithsonian Libraries
Originally published in the Annals and Magazine of Natural History, ser 3, v. 8-9, 12-17 (1861-1866).

Binder's title: Longicorns of the Amazon Valley.

Also available online.

Ent copy 39088003565389 is the 1st title bound with the author's Contributions to an insect fauna of the Amazon Valley (Coleoptera, Prionides). [London] 1869, and Contributions to an insect fauna of the Amazon Valley (Coleoptera,Cerambycidae). [London] 1870.

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