Diversity is strength, even among forests. In a paper published in Nature, researchers led by University of Utah biologist William Anderegg report that forests with trees that employ a high diversity of traits related to water use suffer less of an impact from drought. The results, which expand on previous work that looked at individual tree species’ resilience based on hydraulic traits, lead to new research directions on forest resilience and inform forest managers working to rebuild forests after logging or wildfire.
Surprisingly, says Anderegg, a forest’s hydraulic diversity is the predominant predictor of how well it can handle a drought.
“We expected that hydraulic traits should matter,” he says, “but we were surprised that other traits that a lot of the scientific community have focused on weren’t very explanatory or predictive at all.”
By George Plaven
Timm Locke relishes a chance to drive around Portland and showcase the latest commercial buildings made with mass timber, a construction material that uses wood beams and panels instead of concrete and steel.
First stop: Albina Yard, a four-story office building that opened in 2016 featuring cross-laminated timber panels from D.R. Johnson, a lumber company south of Roseburg.
Every piece of cross-laminated timber — or CLT for short — is prefabricated, designed for a specific part of the building, said Locke, director of forest products at the Oregon Forest Resources Institute. That means buildings go up faster, with fewer workers.
Wood is also environmentally superior to steel and concrete, Locke said, because it sequesters carbon and takes less energy to produce.
“There are so many benefits, it doesn’t matter which one you choose to start with,” Locke said.
First developed in Europe, mass timber is now catching on in the U.S., and Oregon is working to position itself as the industry hub, kick-starting rural economies that have traditionally relied on forest products. On Aug. 1, Oregon became the first state to approve language in its building codes allowing for wood-framed buildings up to 18 stories tall.
By Dylan Love
Called Forester, this robot uses a technique called “sounding” to help arborists identify sick trees and diagnose them.
After hearing a radio program describe the labor-intensive work of forest pathologists — basically, tree doctors — Maksim Mikhailov had an idea: what if a robot helped collect their data?
Mikhailov is a 16-year-old student at ITMO University, the renowned science and technology institution in St. Petersburg, Russia. As a member of the school’s Youth Robotics Lab, he was perfectly positioned to bring his idea to life. With a full team working on the the project, the robot won the gold medal at last year’s World Robot Olympiad; it can record tree locations within a forest, identify their species, measure the widths of their trunks, and even identify if a tree is healthy or not.
Its name is Forester, and most of its job is to explore forests and hit trees with its mallet. It’s a robotic adaptation of a technique that human tree experts often use, called “sounding,” to help their appraisal of a tree’s health.
“The robot hits a tree and its microphone records the sound,” Mikhailov explained. “Since sick trees have cavities or low wood density in their trunk, they make a sound with a lower overall frequency than that of a healthy tree.” The robot makes use of an algorithm that analyzes the recorded sound to determine if it came from a healthy tree.
Forester also takes a photograph of the tree and feeds the image to a neural network, identifying 12 different species of trees with accuracy better than 90 percent.
Peter Krzystek, Professor for Photogrammetry and Remote Sensing at Munich University of Applied Sciences tells about new investigations into the 3D mapping of forests.
Modern remote sensing sensors offer completely new possibilities for an extensive and detailed 3D capture of tree populations, making it possible to map at very large-scale. In particular, LiDAR is today an established technique for fast and highly accurate 3D scanning from the aircraft, helicopter or drone where pulses of visible or near-infrared laser light at a particular wavelength are used to create 3D images. These 3D images are typically made up of a high density of data points, known as ‘point clouds’. The new full waveform technology, which reconstructs the complete path of the laser beam through the vegetation, makes it possible to map the forest structures in 3D more precisely. Moreover, digital aerial cameras enable a detailed reconstruction of the forest surface and provide – if fused with LiDAR data – extra spectral information in the infrared range for a characterisation of the tree species. All in all, these new technologies are ideally suited for the automatic and cost-effective collection and characterisation of forest stands.
By Maria Dolan
Austin, Texas, and King County, Washington, are testing carbon credits for planting and protecting urban trees.
The evidence is in: Urban trees improve air and water quality, reduce energy costs, and improve human health, even as they offer the benefit of storing carbon. And in cities across the country, they are disappearing.
A recent paper by two U.S. Forest Service scientists reported that metropolitan areas in the U.S. are losing about 36 million trees each year. The paper, by David Nowak and Eric Greenfield, was an expansion of the same researchers’ 2012 study that found significant tree loss in 17 out of the 20 U.S. cities studied.
This arboreal decline is happening even in some areas that promote “million-tree” campaigns, Arbor Day plantings, and street-tree giveaways. Cash-strapped municipalities just can’t find enough green to maintain the green. Additionally, many cities are adjusting to population booms, and to temperature increases and drought due to climate change—both conditions that can be hard on trees (while increasing their value as sources of cooling and cleaner air). There’s also a growing recognition of the inequity of tree-canopy distribution in many cities, with lush cover in wealthy neighborhoods and far fewer trees in disadvantaged areas.
To find more funding for urban trees, some local governments, including Austin, Texas and King County, Washington (where Seattle is located), are running pilot projects with a Seattle-based nonprofit called City Forest Credits (CFC). The nonprofit is developing a new approach: generating funding for city tree canopies from private companies (and individuals) that wish to offset their carbon emissions by buying credits for tree planting or preservation.
The vast majority of forest carbon credits worldwide have been issued for trees in tropical rainforests and other forests far from urban areas. A study released last year of the forest offsets in California’s cap-and-trade program found that they are effective at reducing emissions.
By Daisy Dunne
Forests containing several tree species could store twice as much carbon as the average monoculture plantation, research finds.
A study looking at the carbon storage of forests in southern China finds that each additional tree species introduced to a plantation could add 6% to its total carbon stocks.
The findings suggest that afforestation programmes – which aim to plant trees to “suck” CO2 out of the atmosphere – should switch from using just one plant species to a more diverse mix, a study author tells Carbon Brief.
Planting a diverse range of trees could also bring many co-benefits, the author adds, including providing habitats for a larger range of animals.
However, the relatively small scale of the experiment may have led researchers to overestimate the relationship between tree species diversity and carbon storage, other scientists tell Carbon Brief.
By Alan Duffy
Volatile gases emitted by trees scatter light to increase its availability to leaves.
That “pine-smell” you enjoy during a walk in the woods doesn’t just lighten your mood. It lights the entire forest itself.
Research published in the journal Nature Geoscience Letters, and led by Alexandru Rap of the University of Leeds in the UK, has found that the “smell” of a forest, caused by vast quantities of biogenic volatile organic compounds (BVOCs), increases the scattering of direct sunlight and allows it to reach the wider plant-canopy.
Illuminating more of the canopy leads to increased overall growth, more than offsetting the substantial cost in creating the volatiles to the plants, that captures an additional 1.23 billion tonnes of carbon each year.
The impact of these BVOCs was estimated in a simulation framework that included a global aerosol model to track their release across different habitats. It also employed a radiation model that changed the resultant sunlight, and a land surface scheme to model the resulting growth. These models have previously been used to estimate the impact of mass burn-offs in the Amazon region.
The modelling allowed researchers to explore the relatively uncertain range of global BVOCs production, as well as their changing impact on plant response – with some regions actually suffering a small decrease in growth.
The greatest impacts were in South America and central Africa, where direct sunlight scattered into an additional 10 watts of diffuse lighting across each square metre. This drove growth which sequestered an additional 0.2 grams of carbon per day per square metre. Taken globally, the growth more than compensated for the decline in certain regions.
A study carried out by the IIRS has predicted a depletion of 9,007.14 square km (2.94 per cent) of forests in parts of Assam and Arunachal Pradesh by 2028.
A report published in the The Telegraph stated that the study – ‘Forest Cover Monitoring and Prediction in a Lesser Himalayan Elephant Landscape’ – published in the current issue of Current Science, says deforestation and loss of wildlife habitat in Upper Assam is likely to influence not only adjoining Bhutan and Arunachal Pradesh but Lower Assam as well. The IIRS is under the Indian Space Research Organisation (ISRO).
The report further stated that scientists involved in the study said they monitored the depletion of forest cover in parts of Assam and Arunachal Pradesh over 42,375 square km in an elephant landscape falling in the Lesser Himalaya in the North East. The study, which covered a vast elephant landscape spread across West Bengal-Assam, Assam-Bhutan and Assam-Arunachal Pradesh borders in the lesser Himalayas, found a loss of about 7,590 square km (17.92 per cent) of forest cover from 1924 to 2009.
This was also found by US Army topographic maps (1924) and multi-date satellite images. The forest cover of 2028 was predicted using the 2000-2009 depletion of forests study and Cellular Automata Markov Model (CAMM). As elephants are long-ranging animals and are distributed across the landscape, it is important to carry out studies covering large areas to address the habitat status over time, which can be used for effective habitat conservation.
By Neil Shaw
JOHANNESBURG — One of the world’s largest urban forests is under threat from a tiny beetle.
The polyphagous shot hole borer is thought to have made its way to Johannesburg from Southeast Asia on packing crates or through the trade in plant materials.
Trudy Paap, a forest pathologist at the University of Pretoria, discovered the beetle in the Pietermaritzburg Botanical Gardens last year. She published her discovery in the journal Australasian Plant Pathology, calling it part of “the surge in the global spread of invasive forest pests” because of globalization.
The beetle has since moved to Johannesburg, 200 miles away, and spread across its urban forest, which according to the Massachusetts Institute of Technology initiative Treepedia has the world’s sixth-largest green canopy cover.
Today, many of Johannesburg’s estimated 6 to 10 million trees are dying, a crisis obscured only by the current winter season. Some of the infected trees have the telltale holes the 2-millimeter-long beetle makes in their bark.
“This beetle doesn’t actually eat the trees,” Paap said. Instead it carries a fungus that blocks the vessels that transport water and nutrients, “which ultimately leads to die-back and death of the tree.”
Though scientists don’t know just how many trees have died from the beetles’ invasion, the outlook for Johannesburg is grim: “The city is going to lose a lot of trees.”
The trees do not have an evolved resistance to the polyphagous shothole borer, unlike in Asia where the beetles naturally occur.
It is the older, more established trees that are at risk, said arborist Neil Hill. “So that’s going to leave a gap in the landscape. And if we don’t start to plant straight way with new trees that gap is going to become more and more of a concern as far as urban blight, pollution, aesthetic beauty.”
New research suggests the removal of timber harvest residue during harvesting may be a boon for wild bees, an important step toward better understanding the planet’s top group of pollinators.
The findings are important because bees are the driving force behind $100 billion in global economic impact each year, with insect pollinators enhancing the reproduction of 90 percent of the Earth’s flowering plants, including many food crops.
Insect pollinators are also ecologically critical as promoters of biodiversity. Bees are the standard bearer because they’re usually present in the greatest numbers and because they’re the only pollinator group that feeds exclusively on nectar and pollen their entire life.
Researchers at Oregon State University spent two years studying 28 contiguous 1-acre clearcut sites. They assessed whether the abundance and diversity of wild bees was affected by the removal of timber harvest residue, also known as slash, and the soil compaction that goes along with it.
“Bees are important for biodiversity in managed forest landscapes but we just don’t have a very good handle on them in these areas,” said lead scientist Jim Rivers of the OSU College of Forestry.
The study plots occurred within a managed conifer forest in western Oregon. Each plot received one of five unique treatments, ranging from removing only the boles – tree trunks that are used to make lumber – without compacting the soil at all (no heavy equipment used on the plot) to removing all of the logging slash and compacting the entire plot.
The findings were surprising, Rivers said.
“The combination of the most intense timber residue removal and soil compaction treatment made for the greatest number and diversity of bees,” he said.