Tag Archives: Forests

Researchers find a way to grow wood in a lab, and it could curb global deforestation

You’ve probably heard about lab-grown meat, sparing animals from slaughter, and lowering greenhouse gas emissions. Well, it turns out this isn’t the only thing researchers are trying to recreate at a laboratory. A team at MIT in the United States is already working on “growing” wood without relying on sunlight or even soil.

Image credit: Flickr / Chuck Coker

The process is strikingly similar to lab-grown meat. The researchers create structures made of plant cells that mimic wood, but without having to clear down forests. The cells don’t come from trees but instead from a flowering plant called Zinnia originally from Mexico. They are then turned into a rigid structure using plant hormones. They essentially “grow” the wood.

They chose the Zinnia plant because it grows fast and is well studied. The cells reproduced before being transferred to a gel for further development. Once they grew in volume, the cells were tested against different variables such as pH and hormone concentration. It will be a long road to make this cost-effective but the work represents a starting point for novel approaches to biomaterial production, reducing the environmental pressure from forestry and agriculture.

Between 1990 and 2016, over 500,000 squared miles of forests were lost due to wood consumption and the clearing of wooded areas to access arable lands.

The researchers highlighted a number of inefficiencies inherent to agriculture and forestry, some that can be managed such as fertilizer draining off fields, and some that are out of the control of the farmer, such as weather and seasonality. Also, only a fraction of the harvested plant ends up being used for food or materials production.

“The way we get these materials hasn’t changed in centuries and is very inefficient. This is a real chance to bypass all that inefficiency,” Luis Fernando Velásquez-García, who is overseeing the MIT research, said in a statement. “Plant cells are similar to stem cells in the sense that they can become anything if they are induced to.”

To achieve wood-like properties, the researchers used a mix of two plant hormones called auxin and cytokinin. They varied the levels of these hormones so to control the cell’s production of lignin – an organic polymer that gives wood its firmness. The cellular composition and structure of the final product were assessed using fluorescence microscopy.

The researchers acknowledged that they are in a very early stage with these lab-grown plant tissues. They have to keep working on the specifics, such as the hormone levels and the Ph of the gel. “How do we translate this success to other plant species? It would be naïve to think we can do the same thing for each species,” Velázquez-García said in a statement.

David Stern, a plant biologist and President of Boyce Thompson Institute, who was not involved with the research, told Wired that scaling up the study would take “significant financial and intellectual investment” from government and private sources. “The question is whether the technology can scale and be competitive on an economic or lifecycle basis,” he added.

The study was published in the Journal of Cleaner Production.

In 10 to 20 years, it will be so hot that tropical trees live shorter lives

It’s not the best time to be a tropical tree, as rising average temperatures risk impacting their lifespan.

Image credits Roel Brienen.

A new study explains that the longevity of trees at the tropics is shortened by higher temperatures. The findings help further our understanding of how climate change will impact ecosystems in the area and its effects on the rest of the planet. The team argues this is the first direct evidence that tropical trees experience shorter lives in hotter environments, and that forests all around the world will be affected.


“Many regions in the tropics are heating up particularly rapidly and substantial areas will become warmer, on average, than approximately 25 °C,” says Professor Manuel Gloor at the University of Leeds, a co-author of the paper.

“Our findings – which are the first to demonstrate that there is a temperature threshold – suggests that for trees in these regions, their longevity is likely to be negatively affected.”

The temperature above which trees become affected is 25 °C, the paper explains. This result is based on four years’ worth of tree ring data recovered worldwide. Roughly 100,000 trees from 400 species in 3,000 sites across the planet formed the dataset. All in all, the team reports that although tropical trees grow twice as fast as those in cold areas, they also live shorter lives (186 years vs 322 years on average).

Average temperatures in tropical forests today sit between 21 °C and 30 °C depending on location. These averages will rise alongside the rest of the world to around 2.5 °C above pre-industrial levels over the next 10 to 20 years. The effect this will have on trees varies depending on exactly how much hotter it gets. Changes in precipitation patterns (another effect of climate change) are going to exacerbate this ever further.

Substantial areas of today’s rainforests will see significantly lower tree longevity. They only cover 7% of the Earth’s surface, but harbor around 50% of its species of plants and animals, and a corresponding 50% of the planet’s carbon stocks. Any change here will have strong, global echoes for habitats, air quality, and carbon scrubbing ability.

“These results are a warning sign that, along with deforestation, global warming adds extra stress on the Earth’s tropical forests,” says Dr Roel Brienen from Leeds, paper co-author.

“If tropical trees die earlier, this will affect how much carbon these forests can hold, raising concerns about the future potential of forests to offset CO2 emissions from fossil fuel burning. It could also cause changes in biodiversity and a decrease in the number of species on the planet.”

Tropical forests in South America are closest to this threshold, but they’re not the only ones at risk. Even the Congo Forest in west Africa, the world’s second largest but with lower average temperatures, will be affected.

The saddest finding here, in the words of co-author Marcos Buckeridge, Director of the Biosciences Institute of the University of São Paulo, is that it’s “unavoidable”. It’s too late to stop average temperatures from passing this threshold “even if we were to take drastic emissions reductions measures”.

The paper “Global tree-ring analysis reveals rapid decrease in tropical tree longevity with temperature” has been published in the journal Proceedings of the National Academy of Sciences.

Urban Forest.

As cities grow, we must bring the forest into our midst — or pay up

Urbanisation and urban forests are likely to become some of the defining elements of the 21st century, according to research from the USDA Forest Service.

Urban Forest.

Image in Public Domain.

By 2100, forests will likely move from the wild outdoors to a block near you, says the USDA Forest Service. According to a new study, published by researchers at the governmental organization, urban land surface in the Lower 48 states will more than double between 2010 and 2060. That space, as our attractive, well-informed readers already suspect, must come from somewhere — mainly, the surrounding forests and farmland. Along with the fact that size tends to amplify cities’ innate drawbacks, this will have a negative impact on the environmental quality and general well-being of residents.

The big get bigger

Between 2000 and 2010, urban land increased from 2.6 percent of the overall land surface to 3 percent (from 58 million acres to 68 million acres). The states that saw the greatest urban growth were in the South and Southeast: Texas, Florida, North Carolina, Georgia, and South Carolina. The authors anticipate that between 2010 and 2060, that area will increase by a whopping 95.5 million acres, reaching a total of 163 million acres (8.6% of land area). To put that into perspective, the projected increase of 95.5 million acres represents an area larger than the whole state of Montana.

In addition to estimating how urban areas will evolve, the research also freshened up previous assessments on the size of the US’ urban forests. Overall, they contain roughly 5.5 billion trees (39.4% of tree cover) shelling out in excess of $18 billion in benefits to society. That estimated sum includes health benefits associated with better air quality, negative costs from cities’ higher climate change resilience, and savings on energy use. In a previous study, lead author David Nowak of the USDA Forest Service‘s Forest Inventory and Analysis Program found that (among other benefits) urban forests across the US save 670 human lives each year, and help nip 575,000 incidents of acute respiratory symptoms in the bud.

“Urbanization and urban forests are likely to be one the most important forest influences and influential forests of the 21st Century,” said Nowak.

“A healthy and well-managed urban forest can help reduce some of the environmental issues associated with urbanization such as increased air temperatures and energy use, reduced air and water quality, and increased human stress, and ultimately help people living within and around urban areas.”

It’s not just the body either. Spending time in nature simply makes us feel better, and such urban forests could soothe the weary, dreary urban soul.

Greening up the place

So which Americans stand to gain most from trees moving into the big city? One way to find out is by looking at which states have the largest percentage of urban land (and by extension, have the least forests and other wild areas). These states are all along the Atlantic coast and have relatively small total areas: New Jersey, Rhode Island, Massachusetts, Connecticut, and Delaware.

States that have the greatest amount of projected land growth (California, Texas, Florida, North Carolina and Pennsylvania) would also stand to benefit a lot from weaving forest into their to-be-developed areas — especially since the projected increase in each state over the next 50 years is greater than the size of Connecticut (3 million acres).

“Research by the USDA Forest Service is informing cities and communities as they make decisions about managing urban forests,” said Tony Ferguson, Director of the USDA Forest Service’s Northern Research Station and the Forest Products Laboratory.

“By measuring and monitoring urban forests, society can better understand the value urban forests deliver, and how urban forests and their role in reducing pollution and reducing energy costs changes over time.”

The findings likely extend to other countries beyond the US, especially those with a comparable level of development or those which are expecting a rapid rise in urban populations.

All in all, the study’s results line up surprisingly closely with Professor Alan Marshall’s vision of the future cities: Ecotopia 2121.

The paper “US Urban Forest Statistics, Values, and Projections” has been published in the Journal of Forestry.

Sunrise jungle Indonesia.

Hard-pressed by humans, rainforests lost their ability to act as carbon sinks

Rainforests are too degraded to act as carbon sinks any longer, a new paper reports. Averaged across the globe, rainforests now have a positive output of greenhouse gases, prompting the authors to call for urgent conservation efforts that will allow rainforests to re-don the mantle of carbon sinks.

Sunrise jungle Indonesia.

Image via Pixabay.

The team, composed of scientists at the Woods Hole Research Center and Boston University, took a different approach in assessing the health of rainforests. Unlike previous research, which generally focused on deforestation (complete removal of the forests), they worked to account for more subtle changes in the form of disturbance and degradation, both natural and anthropic. These changes include small-scale tree mortality or removal, or forest gains through natural or human-assisted growth.

Sadly, they report that when taking such changes in forest density into account, tropical forests lose their ability to act as net carbon sinks, meaning they emit more carbon that they can capture.

Net producers

The study quantified changes in aboveground forest carbon across tropical America, Africa, and Asia. These areas were selected as the sheer scale of their rainforests provide the greatest ability to act as carbon stores. They’re also the most biodiverse places on the planet, providing a wealth of ecosystem services such as food, fuel, and materials to millions of people — meaning they see a lot of human activity.

The team used 12 years’ worth of satellite imagery (taken between 2003-2014), laser remote sensing technology, and measurements taken in the field to calculate losses in forest carbon from flat-out deforestation as well as the more subtle and fine-grain degradation and disturbance processes, which have previously remained unaccounted-for over large swaths of rainforest. Their findings point to a worrying, death-by-a-thousand-cuts scenario playing out in Earth’s richest ecosystems.

Overall, tropical regions have become a net source of atmospheric carbon, they report. Forests saw an increase in capture power of roughly 437 teragrams of carbon annually (expressed as ‘carbon gains’), but losses amounted to a whopping 862 teragrams — meaning rainforests contribute a roughly 425 teragrams of atmospheric CO2 yearly. Each teragram is equivalent to one trillion grams, one million metric tons, or 1.102.331 short tons. To put that number into context, China and the US emitted some 10,600, respectively 5,100 teragrams of CO2 in 2015 (29.5% and 14.3% of world emissions).

“Gains result from forest growth; losses result from deforestation and from reductions in carbon density within standing forests (degradation/disturbance), with the latter accounting for 68.9% of overall losses,” the team writes.

“In many cases throughout the tropics you have selective logging, or smallholder farmers removing individual trees for fuel wood. These losses can be relatively small in any one place, but added up across large areas they become considerable,” said WHRC scientist Wayne Walker, one of the paper’s coauthors.

Losses and gains aren’t evenly distributed, however. On a by-continent basis, the majority of losses occurred in Latin America (some 60% of loss), in the Amazon forest. Some 24% of loss was seen in Africa, and Asia experienced the least share of total losses, with a little over 16%. Degradation and disturbance were responsible for the lion’s share of continental losses in both the Americas (70% of losses) and Africa (81%), but under half (46%) in Asia. Gains were also predominantly centered in the Americas with nearly 43% of total gains, followed by Africa with 30%, and lastly Asia with 26%.

Such results are worrying, especially at a time when governments around the world are scrambling to meet their commitments to the Paris Agreement and curb climate change. The authors note that ending deforestation, degradation, and disturbance in the tropics and allowing the ecosystem to regrow would cut at least 862 teragrams of carbon per year, some 8% of global emissions. The UN already has a project set in place to help preserve natural carbon sinks — the REDD+ (Reducing Emissions from Deforestation and Forest Degradation), which offers incentives for countries to maintain forests intact. However, it depends on regular access to accurate measurements of incremental gains and losses in forest carbon density, and research such as this one will give us a better understanding of how forests function.

“These findings provide the world with a wakeup call on forests,” said WHRC scientist Alessandro Baccini, the paper’s lead author. “If we’re to keep global temperatures from rising to dangerous levels, we need to drastically reduce emissions and greatly increase forests’ ability to absorb and store carbon.”

“Forests are the only carbon capture and storage ‘technology’ we have in our grasp that is safe, proven, inexpensive, immediately available at scale, and capable of providing beneficial ripple effects — from regulating rainfall patterns to providing livelihoods to indigenous communities.”

The paper “Tropical forests are a net carbon source based on aboveground measurements of gain and loss” has been published in the journal Science.

The forests won’t fix our CO2 problem — in fact, they’ll scrub less than we assumed

Carbon dioxide absorption by growing biosphere may have been overestimated up to now, a new study concludes. This is due to previous estimates not taking into account the limiting factor of essential nutrients on plant development.

Image via Pixabay.

One effect of rising concentrations of CO2 in our atmosphere is that plants have more of the gas — a prime source of carbon — to metabolize, improving growth rates. It also raises average temperatures in cold areas, promoting plant growth. Satellite imagery has shown that while growth has declined in some areas, our planet is getting greener overall.

Climate scientists have pointed out that this increased quantity of plants will be able to scrub even more CO2 out of the atmosphere, forming a natural carbon sink, and helping mitigate our emissions. But they have overestimated just how much the biosphere will grow, and thus how much more carbon it will soak. By testing the effect of higher CO2 levels on forests growing in tropical and subtropical soils, a team from the Western Sydney University in Australia has found that the biosphere will likely grow less than what previous estimates have projected.

Plenty of carbon, scarce phosphorus

The team, led by David Ellsworth of Western Sydney University in Australia, says that forests will absorb around a tenth less CO2 than previously expected, meaning CO2 levels will rise even faster than our current models predict. The main limiting factor opposing CO2’s fertilizing effect is the lack of phosphorous in tropical and subtropical regions, they explain.

To determine how much the biosphere will grow, the team artificially raised CO2 levels in six plots of a mature eucalyptus forest near Sydney, which were growing in characteristically phosphorus-poor soil. The plots were covered in a mix of individuals of diverse species and ages.

Previous similar work in temperate forests (whose soils are much richer in phosphorus) found that CO2 increase could boost growth by as much as 20%. Ellsworth’s team found no evidence of growth boost in their plots at all. They attribute this difference to the limiting effect of phosphorous (a key nutrient) on growth. The results are backed by previous results, showing plant growth in the past 30 years didn’t see as much an increase as we estimated.

Another (very) limiting factor is human activity. Although some forests will grow faster if left to their own devices, we have a pretty consistent habit of cutting them down. Martin Brandt et al. show that while there’s overall more woody vegetation in Africa, the effects of warmer climate and rising levels of CO2 are offset by deforestation for raw materials and arable land in highly populated, humid areas, leading to a decrease in woody vegetation for these regions. The biggest increase in forests was seen in dry areas with low human populations, but it’s unclear if this makes up for the losses in vegetation elsewhere.

Ellsworth also points out that an increase in plant growth doesn’t necessarily translate to an increase in CO2 absorption and storage by plants.

Where does this leave us? Well, while it would be a nice turn of events it seems unlikely that the trees will clean our mess. So overall the situation takes a turn for the worse. Our best bet, as up to now, is to limit emissions and find ways to sequester CO2. In the meantime, we should also try as much as possible to mitigate the damage.

The full paper “Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil” has been published in the journal Nature Climate Change.



Up to 80 percent of all wildfires in the U.S. are started by humans


Credit: Pixabay.

Five out of six wildfires which occurred in the U.S. in the past two decades can be traced back to human activity, a new study found. Human-caused blazes, either on purpose or by accident, have tripled the length of the wildfire season causing it to start earlier in the East and to last longer in the West.

Jennifer Balch, a fire ecologist at the University of Colorado, and colleagues analyzed wildfires occurrences in the country between 1992 to 2011. The researchers found a staggering 1.3 million fires were started by humans, mostly due to trash burning which explained 29 percent of human-started fires. Around 21 percent of fires were due to arson or just as much as there were due to lightning. Another 11 percent can be traced to faulty or misuse of equipment.

Strikingly, one out of five wildfires occurred during the 4th of July. That’s not to say these were the most damaging. While humans are the prime drivers of forest wildfires, we’re responsible for only 44 percent of acres burned.

This chart put together by the researchers show human-triggered wildfire incidence around the country. Credit: PNAS.

This chart put together by the researchers show human-triggered wildfire incidence around the country. Credit: PNAS.

The most human-triggered wildfires can be found in the Southeast. For instance, in Kentucky, West Virginia, and Tennessee fire seasons lasted for more than 200 days on average in a year. In these states, 99 percent of all wildfires are caused by humans. That’s because forests in these states don’t catch fire easily.

“The role that humans play in starting these fires and the direct role of human-ignitions on recent increases in wildfire activity have been overlooked in public and scientific discourse,” the scientists wrote in the Proceedings of the National Academy of Sciences.

Humans are also indirectly responsible for an increase in both frequency and length of wildfires by driving climate change as a result of releasing greenhouse gases in the atmosphere. Four of the worst wildfires since 1960 happened in the last decade, among which 2015 is considered the worst wildfire year on record. A growing number of homes in or near major forests is to blame for this dramatic rise in fires but hotter, drier seasons shouldn’t be ignored. In 2016 alone, wildfire damages amounted to two billion dollars.

[ALSO See] The different types of forests

Generally, wildfires are good for ecosystems. These regenerate the forest, revitalize the watershed, renew the soil, and reset the clock for the ecosystem. Many forests such as pine barrens or lodgepole pine forests can’t even survive without fires since the trees are adapted to only produce seeds following a major fire event. That being said, there’s clearly nothing natural in this recent trend and people should definitely act more responsibly when going out in the forest.

The different types of forests: everything you need to know

Forests cover 1/3 of the earth’s surface and contain an estimated 3 trillion trees. Forests exist in dry, wet, bitterly cold, and swelteringly hot climates. These different forests all have special characteristics that allow them to thrive in their particular climate.

Broadly speaking, there are three major forest zones that are separated according to their distance from the equator. These are:

  • the tropical,
  • temperate,
  • and boreal forests (taiga).

There are also more specific types of forests within these larger regions.

World forest cover. Image credits: NASA Earth Observatory

Tropical forests

Tropical rain forests grow around the equator in South America, Africa, and Southeast Asia. They have the highest species diversity per area in the world, containing millions of different species. Even though they cover only a small part of the earth, they house at least one half of all species. The temperature is stable year-round, around 27°C (60° Fahrenheit). As you can tell from the name, it rains a lot in these forests. Most tropical forests receive at least 200 cm (80 inches) of rain in a year. Tropical forests generally have a rainy and dry season.

Tropical rain forests contain millions of species. Image credits: Thomas Schoch

The high temperatures, abundant rainfall, together with twelve hours of light a day promotes the growth of many different plants. One square kilometer (0.6 miles) can have up to 100 different tree species. Broadleaf trees, mosses, ferns, palms, and orchids all thrive in rain forests. The trees grow very densely together and the branches and leaves block most of the light from penetrating to the understory. Many animals adapted to life in trees — such as monkeys, snakes, frogs, lizards, and small mammals — are found in these forests.

Map of global tropical (dark green) and temperate/subtropical (light green) rainforests. Image credits: Ville Koistinen

The soil can be several meters deep, but due to nutrient leaching, it lacks most of the essential nutrients for plant growth. The thin topsoil layer contains all the nutrients from decaying plants and animals, and this thin layer sustains the many plant species in the forest. One might think that the soil would be very rich because it supports so much life, but when tropical forests are clear-cut, the soil is useless for agriculture after only a few years — when the topsoil becomes depleted.

Different subcategories within tropical rain forests

  • Evergreen: rain year-round, no dry season
  • Seasonal: vegetation evergreen, short dry season,
  • Dry: long dry season in which trees lose leaves
  • Montane: most precipitation from mist or fog that rises (also called cloud forests), mostly conifers
  • Tropical and subtropical coniferous: dry and warm climate with conifers adapted to variable weather
  • Sub-tropical: north and south of tropical forests, trees adapted to resist summer drought

    Mindo cloud forest in Ecuador. Image credits: Ayacop

Temperate forests

Temperate forests occur in the next latitude ring, in North America, northeastern Asia, and Europe. There are four well-defined seasons in this zone including winter. In general, the temperature ranges from -30 to 30°C (-22 to 86 F) and the forests receive 75-150 cm (30-60 in) of precipitation per year. Deciduous — or leaf-shedding — trees make up a large proportion of the tree composition in addition to some coniferous trees such as pines and firs. The decaying fallen leaves and moderate temperatures combine to create fertile soil. On average, there are 3-4 tree species per square km. Common tree species are oak, beech, maple, elm, birch, willow, and hickory trees. Common animals that live in the forest are squirrels, rabbits, birds, deer, wolves, foxes, and bears. They are adapted to both cold winters and warm summer weather.

Global temperate deciduous and mixed forests. Image credits: Terpsichores

Temperate evergreen coniferous forests are found in the northwestern Americas, South Japan, New Zealand, and Northwestern Europe. These forests are also called temperate rain forests because of the large amount of rainfall they see. The temperature stays pretty constant throughout the year, with a lot of precipitation, 130-500 cm (50-200 in). All this rain creates a moist climate and a long growing season, which results in very large trees. Evergreen conifers dominate these forests. Common species are cedar, cypress, pine, spruce, redwood, and fir. There are still some deciduous trees such as maples and many mosses and ferns — resulting in a Jurassic-looking forest. Common animals roaming the woods are deer, elk, bears, owls, and marmots.

Coastal temperate rainforest. Image credits: Sam Beebe

Subcategories within temperate forests

  • Moist conifer and evergreen broad-leaved: mild wet winters and dry summers
  • Dry conifer: at higher elevations, little rainfall
  • Mediterranean: located south of temperate regions around coast, almost all trees evergreen
  • Temperate broad-leaved rainforest: mild, frost-free winters, lots of rain throughout the whole year, evergreen

Boreal forests

Boreal forests, also called taiga, are found between 50 and 60 degree of latitude in the sub-Arctic zone. This area contains Siberia, Scandinavia, Alaska, and Canada. Trees are coniferous and evergreen.

Global boreal forests. Image credits: Terpsichores

There are two seasons here: a short, moist, mildly-warm summer and a long cold dry winter. Temperatures range from -40 to 20°C (-40 to 68° Fahrenheit). Precipitation is usually delivered as snow because it is so cold, 40-100 cm (15-40 inches) each year. The ground is comprised of a very thin layer of nutrient-poor, acidic soil. The canopy lets very little light through so there is usually little growing in the understory. Evergreen conifers with needle leaves that can stand the cold, like pine, fir, and spruce trees, live here. Animals that live in these forests can withstand long periods of cold temperatures and usually have thick fur or other insulation — among them are moose, bears, lynx, wolf, deer, wolverines, caribou, bats, small mammals, and birds.

Aerial view of a boreal forest. Image credits: Cephas

The world’s forests are incredibly diverse and act as a carbon sink! They should be protected for their beauty and functionality.