Tag Archives: tropical forest

Warmer temperatures release carbon dioxide from tropical soils

If current trends continue, global warming will cause a massive release of carbon from soils in tropical forests — soils that contain one-third of the carbon stored in soils globally.

Credit Flickr Darren and Brad (CC BY-NC 2.0)

The input and outflow of CO2 into the soil used to be mostly in balance before humanity started ramping up emissions. The gases released by deadwood and decaying leaves were balanced by the microorganisms that fed on that matter.

But climate change is now altering such balance, researchers are warning.

“Carbon held in tropical soils is more sensitive to warming than previously recognized,” lead author Andrew Nottingham, a researcher at the University of Edinburgh, told AFP. “Even a small increase in respiration from tropical forest soils could have a large effect on atmospheric CO2 concentrations, with consequences for global climate.”

Previous research showed that rising temperatures could release carbon locked away in cooler or frozen soils such as in the Arctic tundra. A study from 2016, estimated that by 2050, soils could release as much CO2 as the US — but that study didn’t even consider tropical soils.

Carbon in tropical soils was thought to be less vulnerable to loss under climate change than is soil carbon at higher latitudes, but experimental evidence for this was lacking. In the new study, Nottingham and his team published evidence showing that tropical-forest soils might be more vulnerable to warming than was initially thought, especially if temperatures continue to rise.

The authors placed warming rods around the perimeter of undisturbed soil plots in a tropical forest on Barro Colorado Island, Panama, increasing the temperature of the soil profile by 4ºC for two years. They periodically measured the efflux of CO2 with a set of chambers placed over the soil. Their results showed observed an unexpectedly large increase of 55% in soil CO2 emissions. Trying to understand the growth, they excluded the roots from the soil under the chambers and realized that most of the extra CO2 was because of a greater-than-expected increase in the respiration of soil microbes.

Extrapolating from the findings, the researchers estimated that if all the world’s tropical soils warmed by 4ºC for a two-year period sometime before 2100, it would release 65 billion tons of carbon, equivalent to about 240 billion tons of CO2, into the atmosphere.

“That is more than six times the current annual emissions from human-related sources. This could be an underestimation, because we might see large continued loss beyond the two years in our experiment,” Nottingham said, also adding that deeper stores of carbon below two meters weren’t taken into account in the study.

The surface temperature of the planet has grown just over one degree Celsius above preindustrial levels. This has been enough to boost the severity of droughts, heatwaves and superstorms, among other climate events. On land alone, the temperature rose 2ºC, doubling the global average.

The study was published in the journal Nature.

This is the tallest tropical tree in the world

Image credits: Robin Martin/Carnegie Institution for Science

Biologists have located the world’s tallest tropical tree, a 94.1-metre (309-foot) specimen in Borneo. It’s not an isolated case – the tree is surrounded by 49 other mammoths.

“I’ve been doing this for a solid 20 years now, and I have to say, this was one of the most moving experiences in my career,” ecologist Gregory Asner from the Carnegie Institution for Science at Stanford University told Mike Gaworecki at Mongabay.

“This tallest tropical tree, and the 49 runners-up, are truly phenomenal expressions of the power of nature.”

The tree was identified with an aircraft called the Carnegie Airborne Observatory, using LiDAR technology. LIDAR, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure distances and ranges — essentially a light-based radar. It’s accurate enough to be trusted, and researchers are confident in the measured height.

“This technique relies on the 500,000 laser shots per second that we fire out of the bottom of the plane as we fly, which provides a very detailed 3D view of the forest canopy down to the ground level,” Asner told Mongabay. “We then digitally process and comb the 3D data for the tallest trees (in this case).”

But just to be sure, Asner returned to the area in a helicopter after he processed the LIDAR data. He found the tree and its canopy and set up a laser scanner, confirming the results. Still, the tree has only been observed remotely and the team intends to visit the it in the following weeks. Without a doubt, it will be a humbling experience.

“The crazy thing is that our tallest tree is immediately flanked to each side by a tree of the same species of Shorea, almost as tall!” said Asner. “So, there are three trees, like brothers, standing above the rest of the canopy. I almost cried as we circled the tree maybe 10 times before the pilot said we had to go back.”

The results were reported just months after Cambridge researchers made headlines with their discovery of a tropical tree measuring 89.5 metres (293.6 feet), in the same area but in a different valley. The purpose of the research is not just to find the biggest trees but rather to understand these populations and figure out how to protect them from threats – especially logging. Asner believes this finding could provide an unexpected boost to their conservation efforts.

If anything, these huge trees can serve as an inspiration for people, motivating them to preserve these true wonders of nature.

“Conservation needs inspiration, and these sentinels of the Bornean jungle provide that to us,” Asner concluded. “This discovery is a gift to science, to the people of Sabah and Borneo, and to the world.”

Pre-glacial topographical reconstruction for Antarctica during Eocene–Oligocene times.

Antarctica was home to a rainforest some 50 million years ago

Scientists who studied sediment cores drilled from the ocean floor off the Antarctic coast, have found on subsequent analysis fossil pollens that came from a tropical forest. Most likely, the continent was covered by rainforest some 52 million years ago. The researchers involved warn however that by the end of the century, ice from the Antarctic might retreat at the current rate of global warming, leaving the continent once again ice-free.

Pre-glacial topographical reconstruction for Antarctica during Eocene–Oligocene times.

Pre-glacial topographical reconstruction for Antarctica during Eocene–Oligocene times.

Kevin Welsh, an Australian scientist who traveled on the 2010 expedition,  said that the international team of researchers he was a part of had discovered temperature-sensitive molecules in the cores showing that Antarctica was as warm as 68°F (20 Celsius) some 52 million years ago.

“There were forests existing on the land, there wouldn’t have been any ice, it would have been very warm,” Welsh told AFP of the study, published in the journal Nature.

“It’s quite surprising, because obviously our image of Antarctica is that it’s very cold and full of ice.”

The warmest global climates of the past 65 million years occurred during the early Eocene epoch (about 55 to 48 million years ago). Back then CO2 estimates of anywhere between 990 to “a couple of thousand” parts per million were presented in the atmosphere, compared to today’s CO2 levels estimated at 395ppm. The high level of CO2 is considered the major driver for atmospheric warming and Welsh said the most extreme predictions by the Intergovernmental Panel on Climate Change would see ice again receding on Antarctica “by the end of the century.”

“It’s difficult to say, because that’s really controlled by people’s and governments’ actions,” said Welsh, a paleoclimatologist from the University of Queensland. “It really depends on how emissions go in the future.”

During this mentioned period, the scientists believe the climate in lowland settings along the Wilkes Land coast (at a palaeolatitude of about 70° south) supported the growth of highly diverse, near-tropical forests characterized by mesothermal to megathermal floral elements including palms and Bombacoideae.

Currently, The ice on east Antarctica is 1.9-25 miles thick, and is thought to have formed about 34 million years ago.

Without more careful monitoring and efforts, some protected reserves are actually doing worse off than before. Wikimedia Commons

Biodiversity in tropical forests is declining, despite protection

Without more careful monitoring and efforts, some protected reserves are actually doing worse off than before. Wikimedia Commons

Without more careful monitoring and efforts, some protected reserves are actually doing worse off than before. Wikimedia Commons

Biodiversity helps keep the world’s ecosystem in balance, and if threatened, it could bring forth destabilization leading to a chain reaction of events, mostly irreversible. Crops would fail, pests and viral infections might surface, CO2 retention might decrease and more – basically, the Earth will have a tougher time fending for itself if its biodiversity is in peril, and consequently the planet will have a tougher time tolerating humans as well.

A new research from a team of biologists at James Cook University in Cairns, Australia has systematically collected standardized data on environmental changes over the past 20–30 years in 60 protected areas across the world’s major tropical regions of Africa, America and Asia.  Standardization was a huge problem for the team since most of the scientists and managers responsible for overseeing protected tropical forests, the most biodiverse ecosystem in the world, used incomparable methodologies, from study to study, to assess the state of their environments.

This resulted in large gaps of data after consulting individual published studies. William Laurance, a conservation biologist at James Cook University, along with colleagues, took a different route and  conducted 262 interviews with field biologists and environmental scientists. Each was asked to complete a detailed 10-page questionnaire. You can imagine the amount of centralization and work that went into this herculean efforts, but after four pain staking years the team of biologists were able to publish their findings. Were they to start from scratch it would have cost billions of dollars and take 20–30 years.

“Our study was motivated by three broad issues: whether tropical reserves will function as ‘arks’ for biodiversity and natural ecosystem processes,” the team wrote.

They added: “Whether observed changes are mainly concordant or idiosyncratic among different protect areas; and what are the principal predictors of reserve success or failure.”

The researchers found that destructive activities upon the tropical forests, like  forest clearance, fires and logging are steadily ‘eating-up’ the habitat. More exactly, 85% of the reserves experienced declines in surrounding forest cover over the study period, whereas only 2% gained forest. They also observed that “air and water pollution, increase in human population densities and climatic change” had a weaker or more indirect impact, of course, along with poaching.

“The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon,” the international team of research wrote.

“Many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses.”

To be fair, this isn’t exactly news to anyone, especially biologists who have long been aware of the problem and have battled authorities for decades now. The numbers, however, serve as an indicator of the state of tropical forests today.

Findings were reported in the journal Nature.

Insects trapped in amber offer a precious glimpse on prehistoric bugs

Amber is not very common, but you can’t say it’s really uncommon either. Bugs in amber – that’s rare, but a huge “stash” such as the one that was found in India – that’s really something out of this world. The bug “collection” that was unearthed seems to suggest that the Indian continent was not really as isolated as previously thought. The findings were published in PNAS (Proceedings of the National Academy of Sciences).

“We know India was isolated, but … the biological evidence in the amber deposit shows that there was some biotic connection,” says David Grimaldi, curator in the Division of Invertebrate Zoology at the [American Museum of Natural History].

Here’s your basic tectonic for you: as you (should) know, the continents looked quite differently 150 million years ago than they do now. Back then, the Indian plate had just separated from the African one and started a journey towards Asia that would last 100 million years, during which the Indian subcontinent was quite isolated from the rest of the world. The fact that it was isolated allowed it to develop some unique and interesting species, including bugs such as the one in the pictures, that lived some 50 million years ago.

“The amber shows, similar to an old photo, what life looked like in India just before the collision with the Asian continent,” says Jes Rust, professor of Invertebrate Paleontology at the Universität Bonn in Germany. “The insects trapped in the fossil resin cast a new light on the history of the sub-continent.”

Many arthropodes are very similar to the ones found in Asia at the time, which leads to the logical conclusion that the two continents had some sort of connection even before they united. The other possibility would rock the scientific world even more, because it could only suggest that the two plates merged earlier than believed.

“They are so well preserved. It’s like having the complete dinosaur, not just the bones. You can see all the surface details on their bodies and wings. It’s fantastic,” Rust told the Guardian.

Just so you can make an idea about how big of a finding this is, it weighs around 150 kilograms and it is about 52 million years old. Not only do the insects give extremely valuable clues, but the amber itself has something to say. The original resin came from a tropical tree family called Dipterocarpaceae that today makes up about 80 percent of forest canopies in Southeast Asia, which makes the tree family and tropical forests in general twice as old as previously believed; and just think, all this, all of this amazing information can be taken from insects trapped in amber !

“The evidence is beginning to accumulate that tropical forests are ancient,” Grimaldi said. “They probably go back to right after the K-T boundary,” between the Cretaceous and Tertiary periods 65 million years ago, when non-avian dinosaurs went extinct.