by Jennifer Chu
The interiors of nonflowering trees such as pine and ginkgo contain sapwood lined with straw-like conduits known as xylem, which draw water up through a tree’s trunk and branches. Xylem conduits are interconnected via thin membranes that act as natural sieves, filtering out bubbles from water and sap.
MIT engineers have been investigating sapwood’s natural filtering ability, and have previously fabricated simple filters from peeled cross-sections of sapwood branches, demonstrating that the low-tech design effectively filters bacteria.
Now, the same team has advanced the technology and shown that it works in real-world situations. They have fabricated new xylem filters that can filter out pathogens such as E. coli and rotavirus in lab tests, and have shown that the filter can remove bacteria from contaminated spring, tap, and groundwater. They also developed simple techniques to extend the filters’ shelf-life, enabling the woody disks to purify water after being stored in a dry form for at least two years.
The researchers took their techniques to India, where they made xylem filters from native trees and tested the filters with local users. Based on their feedback, the team developed a prototype of a simple filtration system, fitted with replaceable xylem filters that purified water at a rate of one liter per hour.
By Tony Barteleme
Turbocharged by a warming climate, rain bombs and rising seas swamped the South Carolina Lowcountry this year, sending murky floodwaters into streets, businesses and homes.
At the same time, developers continue to transform forests and wetlands into even more homes and shopping centers — destroying acres and acres of spongy land that could help sop up these rising waters.
A new analysis requested by The Post and Courier for the Rising Waters project shows how the Charleston area’s unprecedented building boom made us more vulnerable amid the accelerating forces of climate change.
Researchers at the College of Charleston’s Lowcountry Hazards Center used advanced satellite and aerial imagery to measure changes in the area’s tree canopy — a key measure of the land’s ability to naturally manage flooding rains.
What emerged is among the most nuanced looks yet at how our land has changed in recent decades, a powerful new tool for residents and planners alike.
After a record low winter run-off, some water experts are now calling this Arizona’s worst mega-drought in recorded history, even when compared to tree-ring data that goes all the way back to the 1300s.
An insect infestation that is killing hemlock trees in New England forests is having a significant impact on the water resources of forested ecosystems that provide essential water supplies to one of the nation’s most populous regions, according to research by Indiana University geographers and colleagues at three universities in Massachusetts.
The study is the first to show an increase in water yield—the amount of water reaching streams and rivers—resulting from forest damage caused by an insect pest called the hemlock woolly adelgid. Insect-damaged trees use less rainfall and allow more water to reach the ground and run off into waterways. With less foliage, the trees return less moisture to the atmosphere via transpiration and evaporation.
“We observed a 15 percent increase in annual water yield,” said Taehee Hwang, an assistant professor in the Department of Geography in the IU Bloomington College of Arts and Sciences. “But there are a lot of issues involved with this subject. Water quality may suffer as rainfall runs off more quickly from forested areas and carries higher concentrations of nutrients. The long-term picture may change as hemlocks are replaced with broad-leaved trees that have a different impact on water resources.”
By Desmond O’Boyle
The Forests to Faucets partnership originally began in 2010 as a response to a series of wildfires, namely the 1996 Buffalo Creek and 2002 Hayman wildfires. Since its inception, the partnership’s goals have grown to not only reduce catastrophic wildfires, but to also restore forests impacted by reservoirs, erosion and beetle devastation. On Monday, Feb 27, Forests to Faucets was granted a $33 million extension to continue its ongoing projects.
Lawrence Lujan is the regional press officer for the Rocky Mountain Region of the U.S. Forest Service, one of the organizations involved in the partnership. He says the specific strategies will be identified in a 5-year plan.
“Some of the tools in the toolbox include, thinning, prescribed fire, replanting trees, especially in areas that have been impacted by previous fires,” said Lujan. “We’ll be decommissioning roads, taking actions to minimize erosion and sedimentation of reservoirs.”
Locations for forest restoration and wildfire fuels reduction projects include Dillon, Strontia Springs, Gross, Antero, Eleven Mile Canyon, Cheesman and Williams Fork reservoirs. The partnership anticipates treating more than 40,000 acres of land.
A 10-year logging impacts study by University of Kentucky forestry researchers rates management practices used in the state’s prolific hardwood forests effective and advises only minor changes to better protect more than 90,000 streams and rivers.
The study advises doubling the minimum distance between waterways and logging roads or skid trails. Current practice is a minimum of 25 feet, or 55 feet in steeper grounds.
The combination of thriving forest industries and access to an abundance of large and small waterways makes protecting the commonwealth’s water a priority. The UK Department of Forestry has been a partner in the development of best management practices (BMPs) in woodlands since the Kentucky legislature created the Agriculture Water Quality Authority in 1994. The authority’s mission is to alleviate pollution to surface and groundwater resources from agriculture and forestry activities.
UK forestry professors, Jeff Stringer, silviculture, and Chris Barton, forest hydrology and watershed management, oversaw more than a dozen graduate students and a number of undergraduate interns from 2004 to 2014 who examined logging impacts on forest resources in eight watersheds located in Robinson Forest, the UK College of Agriculture, Food and Environment’s research and education forest in southeastern Kentucky. Loggers harvested two watersheds using the current standard for best management practices. They logged four other watersheds using two different BMP treatments that the researchers theorized would provide more protection. Two additional watersheds were left unharvested as controls.
“At the end of the day, what we saw was that our current recommended BMPs do a pretty good job of protecting our water resources,” Barton said. “With that said, we also found that the best management practice changes we made in the other watersheds actually provided some additional protection. Our BMP treatment that provided the most protection was not statistically different than the unharvested control for nearly all of the parameters examined.”
One change resulting from the study was to increase the distance between streams and skid trails and logger roads. The process of mechanically moving trees can create erosion, which ends up in streams.