Tag Archives: tree

A neural network has learned to identify tree species from satellite

A detailed land-cover map showing forest in Chiapas state in southern Mexico. The map was produced using Copernicus Sentinel-2 optical data from 14 April 2016. The image is not part of the discussed study.

Much of what we know about forest management comes from aerial photos nowadays. Whether it’s drones, helicopters, or satellites, bird’s-eye views of forests are crucial for understanding how our forests are faring — especially in remote areas that are hard to monitor on the ground.

Satellite imagery, in particular, offers a cheap and effective tool for monitoring. But the problem with satellite data is that oftentimes, the resolution is pretty low, and it can be hard to tell what you’re looking at.

But a new study using neural networks to distinguish between satellite imagery may help with that.

Hierarchical model structure/Svetlana Illarionova et al., IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing.

“Commercial forest taxation providers and their end-users, including timber procurers and processors, as well as the forest industry entities can use the new technology for quantitative and qualitative assessment of wood resources in leased areas. Also, our solution enables quick evaluations of underdeveloped forest areas in terms of investment appeal,” explains Svetlana Illarionova, the first author of the paper and a Skoltech PhD student.

Illarionova and her colleagues from the Skoltech Center for Computational and Data-Intensive Science and Engineering (CDISE) and Skoltech Space Center used a neural network to automate dominant tree species’ identification in high and medium resolution images.

Classes markup of the study area. Image credits: Illarionova et al.

After training, the neural networks were able to identify the dominant tree species in the test site from Leningrad Oblast, Russia. The data was confirmed with ground-based observations during the year 2018. A hierarchical classification model and additional data, such as vegetation height, helped further enhance the predictions’ quality while improving the algorithm’s stability to facilitate its practical application.

The study focused on identifying the dominant species. Of course, among the forests with different compositions, there will be forests where the distribution is roughly equal between two or even more species, but the compositions of these mixed forests was outside the scope of the study.

“It is worth noting that the “dominant species” in forestry does not exactly match the biological term “species” and is connected mostly with the timber class and quality,” the researchers write in the paper.

Overall, the algorithm appeared capable of identifying the dominant species, although the researchers note that the outcome can be improved by a better training markup, which they plan on doing in future research

“However, in future research, we are going to cover mixed forest cases, which will fall entirely into the hierarchical segmentation scheme. The other goal is to add more forest inventory characteristics, which can also be estimated from the satellite imagery,” the study concludes.

Willow trees could help clean wastewater and produce drugs, fuel in the process

Will we ever find a cost-effective, environmentally friendly way to filter our wastewater? One new study says: willows.

Image credits Karolina Grabowska.

Filtering wastewater through the roots of willow trees could help scrub over 30 million liters per hectare of trees, which is quite a decent amount. While these trees won’t overtake our current water treatment sites just yet, they do show great potential for the job. Willow trees are not just very effective at extracting compounds like nitrogen out of wastewater, the team explains, but they can also tolerate high volumes of it (which is a bit of a prerequisite for a filtration system).

Additionally, the trees can eventually be harvested for their biomass, and used, for example, to make biofuels.

Help from trees

“We’re still learning how these trees can tolerate and treat such high volumes of wastewater, but willows’ complex ‘phyto’-chemical toolkit is giving us exciting clues,” said Eszter Sas, lead author of the study and a PhD student at Université de Montréal.

All in all, roughly six trillion liters of municipal wastewater are partially treated and discharged into the Canadian environment every year. A further 150 billion litres are dumped into the country’s surface waters completely untreated.

Looking for an environmentally friendly solution to the latter bit, the authors estimated how efficient willows, a water-loving tree species, could be at partially-filtering wastewater. They collaborated with a plantation in Quebec to gauge just how much water each tree can process.

They first expected to see the plants react poorly to the wastewater, and as such, see them process lower quantities of water and reduce their rate of growth (their ‘yield’). Willows today are used as a source of raw materials for biofuels and certain chemicals, including some used for pharmaceutical products.

But they report being quite surprised by what they found: a hectare of willow trees could treat around 30 million liters of primary wastewater per year, with yields actually increasing after the trees were exposed to wastewater. The nitrogen it contains is likely a key player in this increase, as nitrogen is not readily available to plants in the wild and forms a natural bottleneck in their growth rate. All in all, the willow trees tripled their biomass production during the study, the team notes. This is a prime source of raw material for renewable lignocellulosic biofuels, also known as second-generation biofuels, which do not compete for raw materials with our food supply networks.

The team also analyzed the biomass to establish what valuable chemicals can be extracted. In addition to salicylic acid (the active component in aspirin), which was present in high quantities, they report that several chemicals with antioxidant, anticancer, anti-inflammatory, and anti-microbial properties were present in high levels. Some of these were induced (not naturally found in willows), while some were naturally occurring, but present at higher levels than expected.

“While most of the induced chemical compounds have not been seen before in willows, some have been observed in salt-tolerant plants such as licorice and mangroves and are known to be potent antioxidants,” said Sas. “Intriguingly, a number of the induced chemicals are entirely uncharacterized and a mystery. It’s amazing how much novel plant chemistry there is still to be discovered, even in willow trees, which have been around for thousands of years.

“It seems likely that we’re still only scratching the surface of these trees’ natural chemical complexity, which could be harnessed to tackle environmental problems.”

Using natural solutions to wastewater treatment, such as filtration by willow trees, would help both reduce operating costs as well as provide a source of bioproducts, as identified by the team in their analysis. In essence, it’s a self-contained, self-operating recycling system that takes in waste and outputs fuel or medicine. Best of all, they should have a low environmental footprint, perhaps even help scrub CO2 out of the atmosphere overall.

“This concept of a biorefinery seems to be fantastic in allowing new environmental technologies to compete economically with the highly established markets of petroleum-based fossil fuels and chemicals while also helping to reduce ongoing human damage to the ecosystem.”

The paper “Biorefinery potential of sustainable municipal wastewater treatment using fast-growing willow” has been published in the journal Science of The Total Environment.

Humanity is making trees grow less and live shorter lives

Forests around the world are feeling the shifts in global climate and atmospheric chemistry, a new paper reports. Trees are growing shorter, and there are fewer and fewer older ones around, as tree mortality is on the rise due to a conflux of factors.

Image credits Ilona Ilyés.

These changes have a profound effect on the overall makeup of forest ecosystems, and can potentially have ramifications for all other ecosystems on the planet.

Tree troubles

“This trend is likely to continue with climate warming,” said Nate McDowell, the study’s lead author and a researcher at the U.S. Department of Energy’s Pacific Northwest National Laboratory.

“A future planet with fewer large, old forests will be very different than what we have grown accustomed to. Older forests often host much higher biodiversity than young forests and they store more carbon than young forests.”

They used satellite imagery and available research on forests to conclude that the average size of trees has been declining over the last century. The changes in trees’ lifecycles are being driven by rising average temperatures and growing concentrations of atmospheric CO2 gases.

Greater availability of carbon in the air makes for more fertile times, as plants use this element to develop and grow. However, higher average temperatures are placing increased stress on the plants and increasing the frequency of damaging events such as wildfires, droughts, and damaging winds — which increase tree mortality. Deforestation also factors in here, further increasing tree mortality and inducing changes in the age and structure of forests.

According to the team, these elements have already induced a noticeable change in the makeup and average age of forests. Such human-induced changes will most likely continue in the foreseeable future, they add, leading to ever-shrinking old-growth forests globally.

Forest life

The makeup and age of individual forests are closely interlinked characteristics, and they’re primarily the product of three different factors: recruitment, which is the addition of seedlings to a community, growth rates, as determined by the net increase in biomass/carbon, and mortality rates.

“Mortality is rising in most areas, while recruitment and growth are variable over time, leading to a net decline in the stature of forests,” said McDowell. “Unfortunately, mortality drivers like rising temperature and disturbances such as wildfire and insect outbreaks are on the rise and are expected to continue increasing in frequency and severity over the next century.”

“So, reductions in average forest age and height are already happening and they’re likely to continue to happen.”

Old-growth forests have different characteristics compared to young ones. They’re different ecosystems, harboring a greater diversity of plants and animals, as well as more biomass overall. They have a greater ability to process atmospheric carbon, and they store more of it. The shift from old- to young-growth forests around the world “has consequences on biodiversity, climate mitigation, and forestry,” McDowell adds.

The problem is further exacerbated by the fact that large areas of old-growth forests lost over the last century weren’t replaced by young forests, but by completely different landscapes and ecosystems, such as agricultural, pastoral, or industrial areas.

Humanity takes a toll

Image via Pixabay.

As our effects on global ecological mechanisms increases, the toll these changes take on forests will increase as well. The team explains that higher concentrations of CO2 only seem to benefit young forests that have abundant nutrients and water. Given that many fertile areas of the world have issues with the supply of either or both of those essential elements, the increase in atmospheric CO2 only brings a modest benefit to forests.

At the same time, higher temperatures promote freak, damaging weather events, and reduce plants’ ability to photosynthesize. The team explains that this temperature-induced impairment is one of the leading causes of the trees’ reduced size. Droughts associated with climatic shifts further impact forest mortality.

Finally, wood harvesting has one of the most profound effects on global forest age seen in the study. Where forests are re-established on harvested land, the trees are smaller and biomass is reduced.

All in all, the findings make it loud and clear that trees are struggling around the world. Forests are seen as an important part of our current global warming mitigation strategies (which are far from sufficient as it is), and the findings showcase that we may have overestimated how much they can help given their current, damaged state.

The paper “Pervasive shifts in forest dynamics in a changing world” has been published in the journal Science.

US trees decimated by invasive species

Trees killed by invasive species also affect the atmospheric carbon dioxide, a new study shows.

Image in public domain.

Biological life has its own ways of getting around, but mankind has sent biological movement into overdrive. Globalization doesn’t only affect our society, it affects all ecosystems. Whether it’s mussels attached on a ship’s hull or seeds and plants being brought unintentionally on international shipments, mankind has become a major driver of invasive species — and the consequences are severe.

The United States has traditionally been home to large forest expanses — but that may no longer be the case. Faced with large-scale deforestation, trees have conceded large swaths of land. Now, they’re faced with a new threat: invasive pests.

Some infestations are well-known. The Dutch elm disease and American chestnut fungal disease, for instance, have made headlines with their devastating effects. But many more are causing damage, researchers say. In the new study, the team described thousands of forest plots across the U.S. and the mortality rates due to 15 major tree pest infestations.

Previous studies have already described some 450 invasive tree pests that can damage or kill trees (most of which were brought through international trade or travel). In the new study, the team assessed just how dangerous some of these pests can be.

Around 40% of all forests in the US are under serious threat from invasive species — and the problem shows signs of getting worse year after year. There are also few possible solutions once a tree population has been infected. In most situations, the best thing researchers can do is quarantine the healthy populations to make sure the pest doesn’t spread to them as well.

Not only can invasive pests kill almost half of the US forests, but the damage cascades onto other species. Entire ecosystems can collapse if the trees are killed, and the potential for natural disasters is substantially raised.

It’s not just local, either — the effects can be felt at a global scale. Trees are excellent tools for carbon storage, and the invasive pests kill enough trees to eliminate 6 million tons of carbon atmospheric carbon storage — the equivalent of adding 4.6 million cars on the roads.

Researchers hope that this will raise awareness on this issue and push the introduction of preventive measures.

Journal Reference: Songlin Fei et al. Biomass losses resulting from insect and disease invasions in US forests, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1820601116.

Ethiopia “breaks” tree-planting record: 350 million trees in a day

The country’s Green Legacy Initiative is underway at over 1,000 sites. According to government estimates, some 350 million trees have been planted.

As climate change continues to take its toll, planting trees and preventing deforestation remain some of our best weapons against it. Ethiopia got the memo: the country planted more than 350 million trees in a single day, officials say, in what they claim is a world record. The previous record was set when India planted 66 million trees in 12 hours.

Prime Minister Abiy Ahmed spearheaded the initiative, which aims to counter the effects of deforestation and climate change in the developing and drought-prone country. Ethiopia’s minister of innovation and technology, Dr. Getahun Mekuria, was in charge of counting the seedlings. According to his tweets, he placed the number at 353m.

The campaign was heavily advertised through promotional videos encouraging people to plant and care for trees. The goal is to plant a total of 4 billion indigenous trees. State workers were heavily involved in the project, with some public offices being shut down to allow civil servants to participate in the planting. Staff from the United Nations, as well as foreign embassies in Ethiopia also participated in the project.

This project is part of a larger effort to build an African “green wall” — an 8,000-km-long tree barrier stretching from the east of Africa to its west.

By now, you’re probably wondering why the quotes in the record “breaking” — it’s because very little proof has been provided to back these numbers up. It’s clear that Ethiopia had a massive tree-planting campaign, but whether or not the numbers add up is a different story. Doubts are particularly pressing since the Ethiopian government recently caused an internet and text-messaging blackout after a claimed coup.

Critics of the current administration have called this move a distraction.

In the early 20th century, Ethiopia’s forest coverage was 35% — by the 2000s, it had declined to a meager 4%. Most of the deforestation in Ethiopia happened as people cleared forests for their own personal needs, most commonly for agriculture, livestock production, and for fuel.

Limiting agriculture in Ethiopia is quite costly, particularly as the country’s coffee industry is thriving — at the expense of trees. Several experiments have shown that the government alone cannot stop the problem, but neither can local groups or market powers. Instead, a combined effort is required, which is why this campaign is encouraging, despite Ethiopia’s very pressing social issues.

This tree stump shouldn’t be alive — but it’s fed by its neighbors

A tree stump in New Zealand manages to keep itself alive by grafting its roots to those of other trees, exchanging water and nutrients through this system. Researchers say this should convince us to think of forest trees less as individuals, and more as “superorganisms”.

The tree stump in the study. Image credits: Sebastian Leuzinger / iScience.

Tree society

It all started when two scientists were hiking in the outskirts of Auckland, New Zealand. They came across something extremely unusual: a tree stump. It wasn’t surprising to find the stump itself, which belonged to a kauri tree, a common species in the area. Rather, it was surprising that it was still alive without any leaves.

“My colleague Martin Bader and I stumbled upon this kauri tree stump while we were hiking in West Auckland,” says corresponding author Sebastian Leuzinger, an associate professor at the Auckland University of Technology (AUT). “It was odd, because even though the stump didn’t have any foliage, it was alive.”

Photosynthesis is a vital process which helps trees to live and grow, but without any foliage, they can’t undergo photosynthesis, and therefore can’t (theoretically) survive. Leuzinger and Bader measured the water flow in both the stump and the surrounding trees (all of which belong to the same species). They found that when water was flowing in the tree stump, it was flowing out of the other trees.

This indicates that the trees are grafted together, and the surrounding trees support it.

“This is different from how normal trees operate, where the water flow is driven by the water potential of the atmosphere,” Leuzinger says. “In this case, the stump has to follow what the rest of the trees do, because since it lacks transpiring leaves, it escapes the atmospheric pull.”

From the stump’s perspective, it makes a lot of sense: it’s probably the only way it can survive. But why would the other trees do it?

“For the stump, the advantages are obvious–it would be dead without the grafts, because it doesn’t have any green tissue of its own,” Leuzinger says. “But why would the green trees keep their grandpa tree alive on the forest floor while it doesn’t seem to provide anything for its host trees?”


There’s no clear answer to this, but Leuzinger has a theory. He suspects that the grafts were formed before the tree became a stump. This would have a couple of advantages for all the trees. For starters, it would provide improved anchorage for all the connected trees — which is important for the steep slope where the kauri trees are located. Secondly, it would enable the trees to share nutrients with one another, creating a more balanced resource distribution.

As one of the trees stopped playing its part in supporting nutrients, this may have just gone unnoticed, or the trees may have continued to support it (it’s unclear exactly how they could stop this from happening).

If this is indeed the case, it opens up an intriguing discussion: are trees more than just isolated individuals? In other words, can we talk about a tree “society”?

“This has far-reaching consequences for our perception of trees – possibly we are not really dealing with trees as individuals, but with the forest as a superorganism,” Leuzinger says.

The question is not straightforward, because the association also comes with downsides. For instance, while this interconnectivity could help some trees cope with drought or insufficient nutrients, it also allows the rapid spread of diseases. The truth is we still don’t know enough about this to draw a definitive conclusion.

“This is a call for more research in this area, particularly in a changing climate and a risk of more frequent and more severe droughts,” Leuzinger says. “This changes the way we look at the survival of trees and the ecology of forests.”

The study was published in iScience https://www.cell.com/iscience/fulltext/S2589-0042(19)30146-4


Credit: Pixabay.

The Earth has room for a trillion more trees — which might be our best bet against climate change

Credit: Pixabay.

Credit: Pixabay.

In order to stave off potentially catastrophic climate change, not only does the world have to urgently stop emitting carbon dioxide, but it also has to find a way to absorb a good portion of it from the atmosphere. Luckily nature has evolved just the right technology that can achieve this goal: good old trees. According to a new study, although humans have massively expanded their reach across the planet, there is still enough room to accommodate 0.9 billion hectares of forest.

Nature’s CO2 removal tool

The study, which didn’t include areas currently occupied by agriculture, cities, and existing forests, estimates that there’s enough room for 1-1.5 trillion trees. Currently, there are an estimated 3 trillion trees sucking CO2 from the atmosphere all around the globe. Forests in the United States absorb and store about 750 million metric tons of carbon dioxide each year, an amount equivalent to 10% of the country’s CO2 emissions.

If allowed to mature, these extra forests would store 205 gigatons of carbon, roughly equal to two-thirds of all the carbon humans have added to the atmosphere since the Industrial Age. This would bring down heat-trapping greenhouse gases to levels not seen for nearly 100 years, according to the authors from the Swiss Federal Institute of Technology, Zurich (ETH Zurich).

“We all knew restoring forests could play a part in tackling climate change, but we had no scientific understanding of what impact this could make,” said study senior author Thomas Crowther, an assistant professor of ecology at ETH Zurich.

During photosynthesis, trees use carbon dioxide (CO2) from the atmosphere with water from rain or irrigation and nutrients from the soil to form carbohydrates, which make up the tree’s biomass. The amount of carbon stored by a tree will depend on its size, which in turn is influenced by the species and local environmental conditions.

Tree biomass percentages (approximate). Credit: Ecometrica.

Previously, the Intergovernmental Panel on Climate Change’s (IPCC) issued a report advising that planting 1 billion hectares of forest is necessary in order to prevent global temperatures from rising over 1.5°C by 2050. This figure inspired Crowther and colleagues to see whether there even was enough room left on the planet’s surface for this many trees.

The researchers analyzed more than 80,000 satellite images, from which they subtracted existing forests, crop fields, and urban areas. Russia has the most space available to accommodate new forests at 583,000 square miles (1.5 million square km), followed by the United States with 397,700 square miles (1 million square km), Canada with 302,700 square miles (784,000 square km), Australia with 223,900 square miles (578,900 square km), Brazil with 191,900 square miles (497,000 square km), and China with 155,200 square miles (402,000 square km).

The reasons why trees are such an appealing solution to tackling climate change is that they’re cheap and do not necessarily require government permission or oversight — anyone can do it, basically. Indeed, various NGOs have so far planted millions of trees. Meanwhile, some government-led projects have also proven highly successful. China has spent more than $100 billion on trees in the last decade alone. Nearly 22 percent of the country is now covered in forest, compared to 19 percent in 2000, according to the Ministry of Environmental Protection.

Meanwhile, the Bonn Challenge, signed and backed by 48 nations, pledged to restore 350 million hectares of forest by 2030. The new study, which was published in the journal Sciencenow offers these countries evidence that they could be even more ambitious. There is, after all, plenty of room to spare!


The birth of forests helped drive two massive, ancient extinctions

The first forests on Earth may have caused massive extinctions of shallow marine life, a new study finds.


Image via Pixabay.

An international team of researchers led by members from The University of Alabama finds that the oldest forests in today’s southeastern North America popped up millions of years earlier than previously believed. At the time, North America was part of a minor supercontinent, which suggests that forests spread across all big land masses today at that time.

They also found evidence that this event happened around the same time as a massive extinction event of shallow marine life about 370 million years ago.

Wooden weapons

“This story is, I think, ironic because today trees are the symbol of eco-friendly green life,” said Dr. Takehito Ikejiri, a paleontologist with UA’s Alabama Museum of Natural History and one of the study’s co-authors.

“But, when they first appeared in Earth’s history, they seemed to be harmful and caused big trouble for other life.”

The work offer insight into the global extinctions 370 to 360 million years ago. It also lends some weight to the theory that these events were caused by a lack of oxygen in the ancient waters, as early forests dumped massive quantities of nutrient-rich soils into the oceans, leading to eutrophication.

We call this period in Earth’s history 393 to 382 million years ago the Devonian era. At the time, Earth’s surface was dominated by supercontinents. Present-day North America was meshed with Greenland and much of Europe into a minor supercontinent known as Euramerica. Here, to the best of our knowledge, the first trees (defined as plants with wood tissues) appeared near today’s New York 393 to 382 million years ago and spread across the continent.

Not long after this (in geological time), almost all of the day’s shallow-water species (such as trilobites, corals, and plankton) experienced two massive die-offs. The reason why was unknown, but our running theories included global cooling, extensive volcanism, asteroid impacts, and marine anoxia — the rapid drop of oxygen levels in the seas.

The team believed that this anoxia could be caused by the newly-spawned forests eroding soils with their deep roots, which would then wash into the sea and create an overabundance of nutrients.

They tested their theory by analyzing an outcrop of black shale from the period from northeastern Alabama. This outcrop lay on the southernmost margin of the Appalachian Basin. Geochemical and microscopic data show that forests first appeared in the region 370 million years ago, then spreading to the southern Euramerica landmass. Man Lu, a UA doctoral student in geological sciences and lead author on the paper, analyzed the samples from these shales and reports finding tiny wood fragments in this Devonian formation where no macro-fossils were reported previously.

Further geochemical data also suggest that these forests became an important carbon source to these black shales during the Late Devonian, providing a rough timeline of how fast these forests evolved during the era.

“Our data show the global forestation occurred in a relatively short time,” Ikejiri said. “Trees spread rapidly in very large areas across the Euramerica continent and likely caused a series of drastic environmental changes.”

It’s not a smoking gun, but the evidence does seem to point to a link between the extinctions and these early forests. Dr. YueHan Lu, UA associate professor of geological sciences and corresponding author of the paper, believes the timing of this rapid forestation is interesting considering it occurs near the time of the marine life extinctions.

The paper “Geochemical Evidence of First Forestation in the Southernmost Euramerica from Upper Devonian (Famennian) Black Shales” has been published in the journal Scientific Reports.

Scientists map global “Internet of Mushrooms”

Fungi are nature’s “Internet” — now, a team of researchers has mapped it.

Above ground and below ground, trees spread out far and wide, offering vital support for countless creatures that rely on their services — including ourselves. But trees don’t live by themselves in a vacuum — they also rely on fungi and bacteria that grow alongside them and offer important nutrients. These symbiotic partnerships evolved more than 500 million years ago and form the backbone of countless ecosystems. Researchers call it the “wood wide web”, a natural information superhighway.

Now, a new effort utilized machine learning algorithms on millions of direct observations from 1.1 million forest sites and 28,000 tree species to produce the first map of this network and gather crucial insights as to how species involved in this relationship flourish or perish.

Forests and microbes are symbiotically connected globally. Now, for the first time, we’re seeing how. Image credits: Sora Hasler.

Each tree in the database was associated with certain types of microbes. For instance, maple and cedar trees prefer a type of fungi called arbuscular mycorrhizae (AM), which drill into the tree roots and build small roots around them. Other trees, like oak and pine, are found alongside ectomycorrhizal (EM) fungi, that build much larger networks. Meanwhile, plants such as legumes prefer bacteria that “fix” nitrogen from the atmosphere into the soil. Imagine all these connections neatly arranged into a giant database — that’s what researchers developed. But they didn’t stop there: they also implemented an algorithm that looks for correlations between these elements and environmental factors such as temperature, precipitation, and soil chemistry. Using this algorithm, they were able to extrapolate and fill in the gaps from places where they didn’t have any actual data, essentially predicting what type of fungi would live in what places.

The result is the first global map of the “internet of fungi.”

The maps from this study will be made freely available, in hopes of helping other scientists include tree symbionts in their work. Image credits: Crowther lab.

The team produced three global maps, one for each type major type of symbiosis (EM fungi, AM fungi, and nitrogen-fixing). The thing is, we don’t really know all that much about how these connections impact mushroom and tree wellbeing, but we’re starting to understand that they can strongly impact the global carbon cycle and climate change.

“There’s only so many different symbiotic types and we’re showing that they obey clear rules,” said Brian Steidinger, a postdoctoral researcher at Stanford and lead author of the paper. “Our models predict massive changes to the symbiotic state of the world’s forests – changes that could affect the kind of climate your grandchildren are going to live in.”

EM fungi, mostly present in temperate areas, are the ones that suck the most carbon and store it beneath the ground. Around 60% of the world’s trees are connected to this type of fungi. However, as temperatures rise, these fungi and their associated trees will decrease, giving way to AM fungi, which spew out carbon into the atmosphere. This will create yet another feedback loop, further accentuating climate change.

It’s possible that the map missed some significant elements, and it will certainly be refined in the future — particularly as it has been made freely available for researchers all around the world to work with. However, it represents the most detailed map of its kind — featuring an ungodly amount of data gathered from 70 countries, which will help us gain an unprecedented look into what is a vital mechanism not only for trees and fungi all around the world, but also for all the creatures depending on them. Yes, including us.

“There are more than 1.1 million forest plots in the dataset and every one of those was measured by a person on the ground. In many cases, as part of these measurements, they essentially gave the tree a hug,” said Steidinger. “So much effort – hikes, sweat, ticks, long days – is in that map.”

The study was published in Nature.

NASA wants you to take photos of trees — to see how much carbon they can store

You can help NASA do a very important job: understand how much carbon trees can store.

Thanks to the advent of technology, we can all help researchers and accelerate the scientific process. There is a myriad of apps and software where you can help, from hunting for star clusters to helping preserve rare species. NASA’s GLOBE Observer app alone has several different tools you can use, such as recording cloud observations, mosquito habitats, and the landscape around you. Now, a new tool called GLOBE Trees has been added.

GLOBE Trees works with data from the ICESat-2 satellite — basically a huge laser in space. ICESat-2 carries an instrument called ATLAS that shoots 60,000 pulses of light at the Earth’s surface every second, which, by knowing the satellite’s exact position and measuring how long it takes the pulse of light to travel to Earth and back, allows researchers to measure the elevation of different features of Earth’s surface. The data is very reliable when it comes to big features such as mountains and hills, but what about more finessed measurements? That’s a big question, says Tom Neumann, the project scientist for ICESat-2 at NASA Goddard Space Flight Center. This is where the tree app comes in.

After a simple and explanatory tutorial, the app Globe Trees asks you to take a photo of a tree. It works like this: you stand 25 to 75 feet (7 to 21 meters) away, snap a photo of the tree, count your steps to the tree, then log your position. The app will give you an estimate of the tree’s height, which will serve as a calibration tool for the satellite.

Selecting trees who’s top is clearly visible from neighbors helps, as does having proper lighting.

“GLOBE observations are available for anyone to view and by submitting your observations, you can help students of all ages do real scientific research as part of the GLOBE Program,” NASA writes. “Everyone can participate, including GLOBE alumni, retired GLOBE teachers, families, and others in the local community.  Download the app, go outside and follow the prompts in the app to observe your environment. And don’t forget to always submit your data to GLOBE!”

It’s a small effort, but so far, fewer than 1,000 measurements have been made. So if you want to spend some time outdoors, look at some trees, and help NASA finesse its satellites, be sure to check out the app.

Oldest tree in eastern North America found in a swamp: it’s 2,624 years old

A recently-documented group of bald cypress trees turned out to be some of the oldest trees in the world — and probably the oldest wetland species alive on the planet; one tree, in particular, is 2,624 years old.

The deciduous Taxodium distichum illustrated here are 1,000 to over 2,000 year old. Image credits: Stahle et al.

The Black River in North Carolina has always played an important part for the local inhabitants and ecosystems. For the early Native Americans who lived in the area, it was a vital source of food and transportation. The river served a similar purpose for European settlers until roads and railroads were developed in the area. Nowadays, while the river is no longer a major source of transportation, it is still used for recreational activities such as fishing, hiking, bird watching, and boating. But despite heavy deforestation and urbanization which threaten local habitats, a small part of the ecosystem in and around the river has managed to remain undisturbed.

David Stahle, professor of geosciences at the University of Arkansas, and colleagues, set out to document the age of trees in a long stretch of intact ecosystem along the river. They used dendrochronology (the study of tree rings) and radiocarbon dating, finding that one tree is at least 26 centuries old.

“It is exceedingly unusual to see an old-growth stand of trees along the whole length of a river like this,” Stahle said. “Bald cypress are valuable for timber and they have been heavily logged. Way less than 1 percent of the original virgin bald cypress forests have survived.” Initially, they were harvesting non-destructive core samples were all initially collected for paleoclimatic applications, but the team returned specifically to measure the age of the trees after realizing some were very old.

The top 10 oldest known trees in the world. Image credits: The University of Arkansas.

This would make the tree the fifth-oldest known non-clonal tree species on Earth, — the oldest clonal species being Utah’s Pando, an ancient aspen forest which reproduces asexually by cloning itself from an 80,000-year-old root system — the world’s oldest wetland tree, and the oldest organism in the world.

The maximum age of wetland trees has not been thoroughly documented. The previous record-holders were also growing along the Black River, but Montezuma bald cypresses (T. mucronatum) in the 1,200 to 1,500-year age class have been reported in Mexico and trees in Chile (Pilgerodendron uviferum) have been found to be at least 859-years old.

The ancient forested wetlands of Black River preserve the oldest living trees in eastern North America and represent a unique natural heritage deserving of permanent protection. Image credits: Stahle et al (2019).

The group of bald cypress trees in this study, however, seem to smash every record. They extended the existing Black River chronology by 970-years and there’s a good chance trees just as old or even older are found in the area, says Stahle, who has been working on bald cypress trees since 1985.

“The area of old growth bald cypress was 10 times larger than I realized,” Stahle said. “We think there are older trees out there still.” So far, only 110 trees have been studied, out of tens of thousands in the area.

In addition to their intrinsic value, these trees can also provide valuable paleoclimatic information about the area. Tree rings are an excellent proxy for the quantity of rainfall in each particular year or season of their life, for instance. Rings form because of the variation in growth speed through winter, spring, summer, and fall, so this growth can be correlated with rainfall and other environmental parameters.

The team is also calling for conservation of the area, to ensure that it and its ecosystems are not lost. The survival of ancient bald cypress and other tree species along the Black River provides a stunning testament to the area’s ecological integrity. Having trees of this age definitely qualifies this stream as one of the great natural wonders of North America. Unfortunately, the ancient forests and waters are both imperiled by continued logging, biomass harvesting for wood pellets and garden mulch, and water pollution from animal farms.

The study has been published in Environmental Research Communications.

Trees help keep cities cool and cozy — especially if there’s a lot of them

The fact that cities are heat islands has been thoroughly documented in recent years — in all parts of the world, urban areas are considerably hotter than their surroundings. However, trees can help counterbalance that phenomenon, helping to keep our cities cooler. The effect is especially pronounced for a large number of trees.

The list of benefits that trees provide in urban areas is huge. Not only do they help absorb carbon and pollutants from the air, but they help with soil erosion and stability, water absorption and filtration, they provide ecosystems for a number of creatures, and offer shade and protection from wind. Studies have shown that trees inspire children to be more curious and fond of nature, increase property values, and can even help reduce criminality rates.

Another service which trees provide is thermal regulation. That has been suggested by previous studies and is quite intuitive. However, a new study shows that the relationship isn’t linear. When the canopy cover reaches a particular threshold, the effect is much more pronounced.

“We found that to get the most cooling, you have to have about 40 per cent canopy cover, and this was strongest around the scale of a city block,” says Carly Ziter, an assistant professor of biology in the Faculty of Arts and Science, and lead author of the study. “So if your neighbourhood has less than 40 per cent canopy cover, you’ll get a little bit of cooling, but not very much. Once you tip over that threshold, you really see large increases in how much you can cool areas off.”

The effects can be huge. The temperature difference from tree-less area just a few hundred meters away from an area with a heavy canopy cover can be as high as four or five degrees Celsius. It’s not just the shade either. Trees transpire, giving off water vapor, almost like a natural air conditioner.

The measurements for the study were simple but very effective. Ziter and colleagues built small, battery-powered mobile weather stations and mounted them on bicycles. They then cycled all around the city, serving as a mobile data stations.

“By doing this over the course of a summer, we found that temperatures vary just as much within the city itself as they do between the city and the surrounding countryside,” she says. “We’re not seeing so much of a ‘heat island’ as a ‘heat archipelago.'”

Researchers hope that their findings will be considered by policymakers and city planners. For instance, cities or areas with a canopy close to 40% would have the most incentives to plant more trees, although in truth, virtually all cities in the world would benefit from having more trees.

“We know that something as simple as having one nice big tree nearby can have a huge host of benefits on people who live in the city,” Ziter concludes.

The study has been published in PNAS.

California redwoods. Credit: CBS This Morning.

Scientists sequence genomes of world’s tallest trees

Coast redwoods and giant sequoia trees are California’s oldest residents, some being more than 2,000 years old. These magnificently tall trees have had their genomes sequenced for the first time, a major breakthrough that scientists claim will help preserve them for generations from the perils of disease and climate change.

California redwoods. Credit: CBS This Morning.

California redwoods. Credit: CBS This Morning.

The $2.6 million Redwood Genome Project, which first began in 2017, is the culmination of state-of-the-art genetic research and the most extensive genetic study ever done on primeval forests. David Neale, a University of California Davis plant scientist who led the project, along with colleagues at Johns Hopkins University and the Save the Redwoods League, used a supercomputer to analyze the DNA extracted from tissues taken from a coast redwood tree (Sequoia sempervirens) in Butano State Park and a giant sequoia tree (Sequoiadendron giganteum) from Sequoia Kings Canyon National Park.

Amazingly, the researchers found that the two species had some of the largest genomes known so far. The coast redwood genome has 6 sets of chromosomes and 27 billion base pairs of DNA, compared to only two sets of chromosomes and nine times fewer base pairs in humans. The giant sequoia has a more modest genome with 8 billion base pairs, but that’s still three times larger than the human genome.

“These narrow endemics play important roles in ecology, economy, culture, and conservation. Although redwoods have been around for millions of years, we know very little about how these trees evolved to occupy their current range,” Neale wrote on the project’s website.

The largest known genome belongs to the axolotl, a North American salamander, which numbers 28 billion base pairs. Researchers believe that its rich genome is what allows the salamander to not only regenerate limbs but also grow back internal organs.

It makes sense for a tree such as a redwood to have a complex genome. These trees can grow in the same place for thousands of years so they require a robust ability to fight off fungi, insects, and significant swings in temperature and humidity throughout their lifetime.

“We’re trying to build a 23andMe for trees, where a manager sends in their samples and gets a risk evaluation of their forest populations, if not individual trees,” Neale said in a statement. “Completing the sequences of the coast redwood and giant sequoia genomes is the first step.”

Sequencing the genomes of the world’s tallest trees, which can reach higher heights than the Statue of Liberty, is paramount to their conservation. Old-growth forests used to grow from the Sierra Nevada range and along the California coast all the way to the Oregon border. Sadly, loggers have cut down more than 95% of these forests since 1850. The few remaining forests have been granted special status and are protected in national parks, however, they are still threatened by climate change.

Ultimately, the project aims to develop genetic variation models for the various groves of old growth. In the future, it might be possible for a forest manager to send no more than a tree’s leaf to a specialized lab and get back a report on the trees and their vulnerability to drought and variations in temperature. This way, they can then make restoration decisions based on genetic diversity. This process to identify flaws in the trees is not all that different from the one that led to new cures for diseases like sickle cell anemia after the human genome was first sequenced in 2000.

“Every time we plant a seedling or thin a redwood stand to reduce fuel loads or accelerate growth, we potentially affect the genomic diversity of the forest,” said Emily Burns, director of science for Save the Redwoods League. “With the new genome tools we’re developing now, we will soon be able to see the hidden genomic diversity in the forest for the first time and design local conservation strategies that promote natural genomic diversity. This is a gift of resilience we can give our iconic redwood forests for the future.”

Urban ‘forests’ can store almost as much carbon as tropical rainforests

We should value urban trees more, shouldn’t we? Image credits: Fons Heijnsbroek.

Most people would never think of London as a forest. Yet there are actually more trees in London than people. And now, new work by researchers at University College London shows that pockets of this urban jungle store as much carbon per hectare as tropical rainforests.

More than half of the world’s population lives in cities, and urban trees are critical to human health and well-being. Trees provide shade, mitigate floods, absorb carbon dioxide (CO₂), filter air pollution and provide habitats for birds, mammals and other plants. The ecosystem services provided by London’s trees – that is, the benefits residents gain from the environment’s natural processes – were recently valued at £130m a year.

This may equate to less than £20 a year per tree, but the real value may be much higher, given how hard it is to quantify the wider benefits of trees and how long they live. The cost of replacing a large, mature tree is many tens of thousands of pounds, and replacing it with one or more small saplings means you won’t see the equivalent net benefit for many decades after.

The trouble with measuring trees

Trees absorb CO₂ during photosynthesis, which is then metabolised and turned into organic matter that makes up nearly half of their overall mass. Urban trees are particularly effective at absorbing CO₂, because they are located so close to sources such as fossil fuel-burning transport and industrial activity.

This carbon storage potential is an extremely important aspect of their value, but is very hard to quantify. A 120-year-old London plane tree can be 30 metres tall and weigh 40 tonnes or more, and some of the carbon in its tissues will have originated from Victorian coal fires.

Measuring the height of a tall tree is difficult, because it’s rarely clear exactly where the topmost point is; estimating its mass is even harder. Typically, tree mass is estimated by comparing the diameter of the trunk or the height of the tree to the mass of similar trees (ideally the same species), which have been cut down and weighed in the past. This process relies on the assumption that trees of a certain species have a clear size-to-mass ratio.

But a fascinating property of trees is how variable they can be, depending on their environment. So inferring the mass of urban trees from their non-urban counterparts introduces large uncertainties.

Lidar over London

The UCL team use a combination of cutting-edge ground-based and airborne laser scanning techniques, to measure the biomass of urban trees much more accurately. Lidar (which stands for light detection and ranging) sends out hundreds of thousands of pulses of laser light every second and measures the time taken for reflected energy to return from objects up to hundreds of metres away.

When mounted on a tripod on a city street, lidar builds up a millimetre accurate 3D picture of everything it “sees”, including trees. The team are using lidar methods, which they pioneered to measure some of the world’s largest trees, and applying them to trees in the university’s local London Borough of Camden.

The UCL team used publicly available airborne lidar data collected by the UK Environment Agency, in conjunction with their ground measurements, to estimate biomass of all the 85,000 trees across Camden. These lidar measurements help to quantify the differences between urban and non-urban trees, allowing scientists to come up with a formula predicting the difference in size-to-mass ratio, and thus measuring the mass of urban trees more accurately.

The findings show that Camden has a median carbon density of around 50 tonnes of carbon per hectare (t/ha), rising to 380 t/ha in spots such as Hampstead Heath and Highgate Cemetery – that’s equivalent to values seen in temperate and tropical rainforests. Camden also has a high carbon density, compared to other cities in Europe and elsewhere. For example, Barcelona and Berlin have mean carbon densities of 7.3 and 11.2 t/ha respectively; major cities in the US have values of 7.7 t/ha and in China the equivalent figure is 21.3 t/ha.

A story to tell

Trees matter, to all of us. Recent protests in Sheffield, Cardiff, London and elsewhere, over policies of tree management and removal show how strongly people feel about the trees in their neighbourhood. Finding ways to value trees more effectively is critical to building more sustainable and liveable cities.

Measuring trees in new ways also helps us to see them from a new perspective. Some of these trees have incredible stories to tell. Just one example is an ash, tucked away in the grounds of St. Pancras Old Church, one of London’s (and indeed Britain’s) oldest Christian churches.

The tree has an extraordinary arrangement of gravestones around its roots, placed there when the railway was built from St Pancras in the mid-19th century. The job of rehousing the headstones was apparently given to a young Thomas Hardy, working as a railway clerk before going on to achieve literary fame. The UCL team’s 3D lidar data are helping monitor the state of this “Hardy Ash” tree in its dotage. This is just one of the ways new science is helping tell the stories of old trees.

Mathias Disney, Reader in Remote Sensing, UCL

This article was originally published on The Conversation. Read the original article.

Meet the oldest tree in Europe

A Heldreich pine discovered in southern Italy has been thriving for more than 1230 years.


Sure, it’s seen some better days, but this pine is still alive and kicking — it’s actually doing quite fine: a thorough examination showed that it’s been having a growth spurt in recent decades, with larger and larger tree rings being added to its trunk.

The discovery was made by Gianluca Piovesan and his fellow researchers at the Università della Tuscia. They spent three years sampling trees in Pollino National Park, which is located in a remote region of southern Italy that is home to thousands of Heldreich’s pine trees (Pinus heldreichii).

This species, often referred to as the Bosnian pine, is native to mountainous areas of the Balkans and southern Italy. The species has been known for its longevity for a while, and in 2016, a tree in northern Greece was dated as 1075. Another notable specimen from Bulgaria, known as Baikushev’s pine, is estimated to be over 1,300 years old, though this has not been confirmed.

Establishing the pine’s age wasn’t easy. When researchers tried to collect a sample from its trunk, they found that the central part of the tree, which contained its youngest years, was almost completely missing.

“The inner part of the wood was like dust—we never saw anything like it,” says team member Alfredo Di Filippo. “There were at least 20 centimeters of wood missing, which represents a lot of years.”

Since dating it only from trunk rings was out of the question, researchers turned to another part of the tree: its roots. Its roots were in much better shape, and they also produce annual rings. However, the rings of the roots and those of the trunk don’t always correlate. Thankfully, researchers were able to use radiocarbon dating and assess when the tree first germinated: 1,230 years ago. Using this information, they were able to cross-correlate the root rings, and assess the years which were missing from the trunk, and the timeline of the pine tree was established much more precisely, Piovesan says.

While it may not seem in optimal shape, the tree is doing quite well. In recent decades, its rings have gotten wider, which signals suitable environmental conditions. This also suggests that the tree has gotten significantly larger recently.

The rings can further be used to gain information about how the tree’s environment changed over the centuries, and how trees can survive periods of extreme droughts or flooding, as well as climatic shifts. It’s not clear exactly what allowed this tree to thrive for so long, but scientists have a few ideas. Mountains have their own microclimate, where temperatures remain cooler and tend to exhibit smaller changes. Piovesan also believes that recent pollution reducing and rewilding policies implemented in Europe helped. Biologically speaking, trees (and especially conifers) are more or less immortal and can go on living indefinitely. Extremely old trees are often toppled by external events, such as strong winds.

Higher temperature and more CO2 is good for trees, but overall climate change will damage forests

Climate change won’t do the world’s forests much good. A new paper reports that certain shifts, however, may actually play in the trees’ benefits and take the edge off the risks they face. However, the authors warn that overall, climate change will negatively impact trees, and identifies which forests are likely to fare better or worse.

Tree forest.

Image credits Michael Gaida.

It’s hard to overstate how critical healthy forests are for ecosystems worldwide. They underpin water and nutrient cycles, soak up a huge quantity of carbon, and provide room and board for a huge number of species. So anything that has the potential to kill trees off is bad news for pretty much everything else on the planet — rising temperatures and more frequent droughts associated with climate change certainly have that potential.


The problem isn’t just that these changes are taking place, but the specific way climate change is inflicting them on the trees causes additional hardships for them. Low levels of rainfall are certainly a problem if you’re a tree, but it’s an especially bad problem during the growing season, for example.

Then, there’s the mixed-bag of problems. These impact the trees both negatively and positively. Take higher concentrations of CO2 in the air, for example. They lead to higher average temperatures, which on the one hand mean that trees have to transpire more, and water evaporates from the ground faster, so the trees have less to spare. On the other hand, more humid air, coupled with higher levels of CO2 means the trees can grow more efficiently (“carbon fertilization effect”).

To get an estimate of how these effects stack up, a team of researchers at Duke University tried modeling these different effects under a range of different climate change scenarios. Led by Yanlan Liu, a PhD student at the university’s Nicholas School of the Environment, the team estimated the toll climate change will take on 13 forests in tropical and temperate settings from around the world. Both broadleaf forests (such as those in the eastern USA or the Amazon) and needleleaf forests (like those in Canada) were included in the analysis.

For their predictions, the team worked with a wide range of possible future changes in temperature and precipitation levels. They combined this data with models describing how trees absorb water and CO2 under different conditions to estimate how each scenario would affect forest death.

Killer heat

Their first models looked just at precipitation and temperature. Assuming mean global temperatures will increase by around 1.4°C by 2065, evergreen needleleaf forests will take a very strong hit. The particular combination of drought and heat under this scenario would increase the “absolute risk of mortality” for needleleafs from under 3% to 10% (a 200% increase). Deciduous broadleaf forests and jungles would see smaller increases in risk.

Once the rise in humidity and CO2 levels were factored in, the results changed quite significantly. Evergreen needleleafs would see a 101.1% increase in relative mortality risk (from 3% to 6%), jungles would see a 19.6% increase, while deciduous broadleafs will actually fare a bit better than before and see their relative mortality risk drop by around 18.3%.

The team notes that because there’s so much uncertainty built into the models their results span a wide range of possible outcomes. The main takeaways, however, stay quite similar throughout.

In almost every scenario, from very mild changes to the really dramatic ones, evergreens see an increase in relative mortality risk (even after factoring CO2 and humidity). Jungles fare pretty OK unless we’re talking about more extreme climate changes (CO2 and humidity did mitigate the effects but not fully). Deciduous forests remain largely unaffected by milder changes and actually see lower relative mortality risks in more extreme scenarios. Still, these findings should be taken with a grain of salt.

The authors explain that the factors they modeled aren’t the only effects that play a role in forest health. Other climate-related phenomena like forest fire frequency or insect prevalence will take their toll so overall, the “estimated risk should be interpreted with care,” the authors note.

We still don’t understand what plays into tree’s mortality risk, the team concludes, but even so, the findings should give us a general idea of what to expect in the future — and we should plan our conservation efforts accordingly.

The paper “Increasing atmospheric humidity and CO2 concentration alleviate forest mortality risk” has been published in the journal Proceedings of the National Academy of Sciences.

Chicago tree map reveals intriguing pattern: trees seem to reduce crime rate

The most comprehensive tree canopy data set of any region in the U.S. reveals many interesting things, including a startling correlation. Whenever trees go up, crime goes down.

A map of the canopy in the Chicago region (Chicago Region Trees Initiative).

A tree with fruit

The Chicago Region Tree Initiative and Morton Arboretum overlaid a wide variety of data to come up with an extremely detailed interactive map. They combined results with LIDAR imagery, a surveying method that measures distance to a target using a pulse laser. This allowed them to map canopy coverage in great detail.

But creating the map was only the first step. They then started to correlate it with demographic information and look for patterns.

“We’re able to layer heat island data; demographic information such as age, vulnerable population, education background; we’re layering Medicaid claims because we know there’s a correlation between health issues—cardiopulmonary problems—and loss of trees,” says Lydia Scott, director of the Chicago Region Trees Initiative (CRTI).

Left: the LIDAR point cloud. Right: how the LIDAR information is sorted into the seven land cover classes. Image credits: CRTI.

Indeed, the benefits of trees in urban areas have long been discussed. Not only do they stabilize water circulation and prevent soil erosion, but they’re also good for our health. They can capture up to half of the particulate pollution in the air, reduce the risk of cardiovascular diseases and diabetes, and help with our mental health.

They were expecting to find such correlations, which they did, but they also found something they weren’t expecting.

The root of crime

Chicago is not really what you would call a peaceful city. The city’s crime rate is substantially higher than the country average, being responsible for nearly half of 2016’s increase in homicides in the US. It’s not yet clear what causes this unusual criminality, and it’s not yet clear how the problem can be solved. But to some extent, trees seem to help.

“We started to look at where we have heavy crime, and whether there was a correlation with tree canopy, and often, there is,” says Scott. “Communities that have higher tree population have lower crime. Areas where trees are prevalent, people tend to be outside, mingling, enjoying their community.”

Trees can prevent crime by improving mental health, promoting a sense of community and safety, and even by eliminating heat islands. Image via Flickr.

Chicago’s richest and safest areas tend to have high canopy covers, up to 40 percent. Meanwhile, on the economically depressed South Side, canopy cover can be as low as 7 percent. The map seemed to show, time after time, that areas with rich canopies are safer, and the ones with high criminality are “tree deserts.”

It seems like a strange idea to digest.

“When we go to talk to communities,” says Lydia Scott, “We say ‘trees reduce crime.’ And then they go, ‘Explain to me how that could possibly be, because that’s the most bizarre thing I’ve ever heard.’”

As Atlas Obscura also points out, it seems like one of those “correlation, not causation” things — and this also makes a lot of sense. Poorer neighborhoods see fewer investments and less taking-care-of, so it might be that poorer neighborhoods, which often have high crime rates, just tend to have fewer trees. In other words, criminality and a lack of trees may not be cause and effect but may have a common cause.

However, Scott and colleagues point out to a number of studies indicating the benefits of urban trees, including several which discuss mental benefits. Among those studies, one suggests that trees “may deter crime both by increasing informal surveillance and by mitigating some of the psychological precursors to violence.”

Help the trees help us

Planting trees with Blacks in Green. Image credits: Blacks in Green.

Scott immediately met with the mayor to present their findings and encourage the municipality to start planting more trees strategically — in areas that need them most. Of course, it will take a long time before the benefits are truly reaped, but even in the short term, trees can help communities. They help with both flooding and droughts, they improve property values, provide shelter against the heat and promote feelings of safety.

But, as Blacks in Green, a Chicago-based economic development organization which aims to create self-sustaining black communities through green initiatives learned, trees can do so much more for a community.

“We’re using the green economy to galvanize, organize, energize,” founder Naomi Davis told Atlas Obscura. Davis has met with Scott and CRTI multiple times over the last few years in order to plan BiG’s approach. “When you’re starting something, you should take stock of what you got,” Davis says. “We realized we were going to need to start with a tree inventory. Now we’re finally getting that inventory.”

To make this point, BiG started buying lots from the city (for $1). They’ve created a charming little orchard, with plum, crabapple, and pawpaw trees.

“We are looking at what it would mean to have a green, healthy space in a blighted African-American neighborhood…We have a really nasty, barren, burnt out commercial corridor, which is 61st Street. Last year we planted about 45 trees there.”

When people work to plant or maintain such green spaces, they’re bonding and creating a sense of community, which also helps reduce crime. It could also help people learn a new skill which could land them a job.

“This is something that is a strong career for good-paying wages,” Davis says. “We’re gonna need more trees than ever to be planted because of climate change.” BiG will have a horticulturalist career fair in October. “In a neighborhood where unemployment is so high,” she says, it’s a game-changer.

It’s hard to say exactly how and exactly how much, but it seems clearer and clearer that trees prevent a stunning number of benefits, especially in urban settings. But they’re also at risk, due to invasive species, improper caring, and rising temperatures. Hopefully, municipalities and policy makers will understand these aspects and

Credit: Massachusetts Institute of Technology.

Tree-on-a-chip mimics passive pumping mechanism found in plants and trees

Inspired by natural hydraulic pumps found in trees and plants, MIT engineers devised a ‘tree-on-a-chip’ which mimics the process. The tiny chip can pump water out of a tank for days without moving parts or external pumps. Such a chip could prove useful in a wide range of applications like that require minimal energy input.

Credit: Massachusetts Institute of Technology.

Credit: Massachusetts Institute of Technology.

The group led by Anette “Peko” Hosoi, professor and associate department head for operations in MIT’s Department of Mechanical Engineering, were looking for an effective way to drive hydraulic actuators for small robots. The ultimate goal is to make a small robot that’s just as versatile as Boston Dynamics’ Big Dog, a four-legged, 240-pound robot that runs and jumps through almost any kind of terrain, no matter how rough.

Scaling down the hydraulic pumps and actuators found in Big Dog can be extremely challenging, however, not to mention expensive. Looking for the best way to generate passive pumping, the MIT researchers eventually found their solution in plain sight: trees.

“It’s easy to add another leaf or xylem channel in a tree. In small robotics, everything is hard, from manufacturing, to integration, to actuation. If we could make the building blocks that enable cheap complexity, that would be super exciting. I think these [microfluidic pumps] are a step in that direction,” Hosoi said.

Beneath the thick bark, inside every tree is a complex plumbing system consisting of a vast network of conduits. This network consists of xylem and phloem tissues which transport water and nutrients (sugars) similarly to how our very own vascular system works. These conducting tissues start in the roots and transect up through the trunks of trees, separating into the branches and then branching even further into every leaf.

Propelled by surface tension, water travels up the channels of xylem, then diffuses through a semipermeable membrane into the phloem channels that contain sugar and other nutrients. This way vital water migrates from the roots to the crown and sugars produced by the leaves travel back to the root.

Previously, other groups had tried to make microfluid chips that emulate this perfect balance but these fell short because typically pumping could be sustained for only a couple of minutes. Jean Comtet, a former graduate student in MIT’s Department of Mechanical Engineering, found out what previous models were missing — emulating the tree’s leaves.

While other tree-on-a-chip designs only emulated the xylem and phloem, Comtet helped devise a new model which also accounts for the sugar transport in the leaves.

First, two plastic slides were sandwiched together, then small channels were drilled inside representing the xylem and phloem. The Xylem channel is filled with water and phloem one with water and sugar. In between the two slides, a semipermeable material mimics the diffusing membrane between xylem and phloem. The real innovation was another membrane placed over the phloem channel slide where a commo sugar cube was placed on top representing the additional sugar intake diffusing from the tree’s leaves.

The whole setup was hooked up to a tank filled with water on one end and a beaker at the other end where the water would flow. Tests showed that constant flow could be sustained for several days as opposed to mere minutes. In other words, this was a huge breakthrough.

 “As soon as we put this sugar source in, we had it running for days at a steady state,” Hosoi says. “That’s exactly what we need. We want a device we can actually put in a robot.”

Journal Reference: Passive phloem loading and long-distance transport in a synthetic tree-on-a-chip, Nature Plants, nature.com/articles/doi:10.1038/nplants.2017.32


Credit: Scott Hughes/Flickr.

Meet the deadliest tree in the world. It’s so dangerous you could die just by standing underneath it

Credit: Scott Hughes/Flickr.

Credit: Scott Hughes/Flickr.

A vacation on a sunny island in the Caribbean could take a turn for the worse if you’re unfortunate enough to come across the manchineel. No, it’s not some drug trafficking gang nor some venomous creature. It’s a tree whose green fruits look a lot like crabapples. Munch them and you’ll get diarrhea and stomach burns faster than Eve got kicked out of Eden. Eat enough of the toxic fruit and you’ll die. The tree is so dangerous even standing beneath it on a rainy day could be fatal as the tree’s bark is laced with water soluble toxins.

This is where Snow White’s stepmother sources her goods

Locals where the manchineel tree (Hippomane mancinella) is native — places like South Florida, the Caribbean, Central American, and northern South America — have learned to keep away from it. They even gave it an ominous name in Spanish, arbol de la muerte, so people know they shouldn’t mess with it, which literally translates into “tree of death.”

The manchineel's fruits look like green apples which is why it's earned the name of 'little apple of death'. Credit: Photo: ason Hollinger/flickr.

The manchineel’s fruits look like green apples which is why it’s earned the name of ‘little apple of death’. Credit: Photo: ason Hollinger/flickr.

If you’re strolling through some of the paradisiac places where the manchineel grows, you should likely see the trees marked with some danger signs or big painted red crosses as captioned above. Some trees may elude markings, though, which is why every year a select few get poisoned. It happened to Nicola Strickland and her friends in 1999 while vacationing in the Carribean. Attracted by colorful green fruits which looked like small apples, Strickland and gang took a few bites of the fruit. Not too long after their throats tightened to the point they could barely swallow anymore.

No one died that fateful day, though, since the group was lucky enough to ingest only a few bites. Strickland, who is a radiologist, published her experience in The British Medical Journal.

“I rashly took a bite from this fruit and found it pleasantly sweet. My friend also partook (at my suggestion). Moments later we noticed a strange peppery feeling in our mouths, which gradually progressed to a burning, tearing sensation and tightness of the throat. The symptoms worsened over a couple of hours until we could barely swallow solid food because of the excruciating pain and the feeling of a huge obstructing pharyngeal lump. Sadly, the pain was exacerbated by most alcoholic beverages, although mildly appeased by pina coladas, but more so by milk alone,” she wrote.

“Over the next eight hours our oral symptoms slowly began to subside, but our cervical lymph nodes became very tender and easily palpable. Recounting our experience to the locals elicited frank horror and incredulity, such was the fruit’s poisonous reputation.”

The medical problems are caused by the milky sap that oozes out of the tree. When coming in contact with the skin, it causes blistering, burns, and inflammation. Burned manchineel wood could also cause problems if the smoke gets in the eyes. According to a 1984 study, tigliane phorbol esters seem to be toxic compounds that cause these symptoms.

While the esters are found in high concentration in the green fruits, the whole tree packs the toxins — bark, leaves, fruits. Even if you don’t touch the tree itself, you run at risk of getting burned by the caustic esters if these are transported on your skin somehow, such as when it rains. In fact, this is how Calusa native North American fighters from Florida won against conquistador Juan Ponce de Leon and his expedition when they tried to conquer the peninsula in the 16th century. The natives made poisoned arrows out of the manchineel sap and one such arrow struck de Leon in the thigh. He retreated in Cuba where he later died from the toxins. Legend has it, also, that the natives would torture prisoners by placing them beneath the tree when it rains. The highly caustic water blinded the prisoners and caused terrible pain.

Seeing how the manchineel is so dangerous, why don’t we just destroy it? Ethics aside, the manchineel tree is actually useful. It provides windbreaking and protection against coastal erosion on Central American beaches. Carpenters have been using its prized wood for centuries to make furniture out of it, being careful to cut the bark and leave the wood in the sun until the toxins are neutralized. It also has medical properties, as it can treat edema in gum form, while dried fruits have been used as a diuretic — of course, you have to be very careful about it.

From an evolutionary perspective, it’s clear the manchineel adapted this trait for protection but it’s not clear what could have tempted it to go to such extreme. Being so poisonous, it can’t rely on animals to spread its seeds, which is a disadvantage, but it seems to make up for it by leaving in coastal areas where the wind can do the job.

It’s not so often that you hear about a killer tree, not unless you count crashing a car into one. We’re used to seeing trees as benign but the manchineel proves there’s more to it. So, next time you vacation in an exotic location, be sure to get all your shots and, most importantly, read about dangerous local fauna.



Manchester, UK, plans to plant a tree for every man, woman, and child in the city

Manchester officials have announced plans for a City of Trees: 3 million new trees will be added to the city area over the next 25 years, one for every city inhabitant.

Trees provide numerous environmental and health services. Image credits: torbakhopper / Flickr

Trees do wonders for a city. They improve air quality, help regulate temperature, and reduce stress. But even so, most cities are ignoring their green spaces in favor of improving traffic or urban development. The concrete jungles are becoming less and less green in many parts of the world, and this is what Manchester wants to avoid — but planting a whole lot of trees.

It’s not just about planting new trees, however. A lot of it about making people understand the benefits of trees and creating an interactive relationship. City of Trees director Tony Hothersall explained that there are three main benefits to this scheme:

“One is to plant three million trees, ie. a tree for every man woman and child, over the next 25 years,” he said.
“Next, we are very much focused on bringing existing woodland into management because there is no point in planting new woodland if you can’t manage what you’ve got already.
“Finally, we want to engage people a lot more in their natural environment; in planting trees; in managing areas; in understanding more about the benefits that trees and woodlands bring to our society.”

The trees are not going to be all in one place, but rather spread around the city. Basically, they want to green up the entire city and bring a lot of biodiversity along with the trees. Furthermore, people have to “grow” with the trees as well. The first stage is raising awareness and next one is involving the local communities in the project — that’s why the tree placement is extra important.

“It is really about planting trees wherever it’s appropriate to put trees,” he explained, “what is really important is it’s about the right tree in the right place.”

What we really dig about this project is that it keeps the full frame of sustainability in mind and it understands the significance of having natural oases in cities. Too often cities forget how vital green areas are to a city.

“Greater Manchester wants to be a world-class city region. We have a lot of fantastic built development going on, but the natural environment needs to keep up with that,” Mr Hothersall said.

This could be even more important in a global warming context. We know that cities are hotter than the surrounding environment (especially on weekdays) and that temperatures are expected to rise more and more in following decades. That takes a big toll on the health and life quality of the city’s inhabitants. Hothersall continues:

“In terms of health… woodlands can do great things in terms of air pollution reduction… [and] can help to screen for noise pollution. They can also help cities and towns become more resilient to climate change both in terms of things like reducing the urban heat island effect and also reducing things like risk from surface water flooding.”

Lastly, trees also provide a number of secondary environmental services — many of which we don’t even properly understand. For example, researchers from the University of Manchester are working with people in the project to see how tree planting could reduce flooding in built-up areas. Bravo, Manchester, bravo!

EDIT: This article had a massive error in its title, thank you to so many of you for pointing it out. We apologize!