Pine beetle outbreak buffers watersheds from nitrate pollution

University of Colorado-Boulder News: A research team involving several scientists from the University of Colorado Boulder has found an unexpected silver lining in the devastating pine beetle outbreaks ravaging the West: Such events do not harm water quality in adjacent streams as scientists had previously believed.

According to CU-Boulder team member Professor William Lewis, the new study shows that smaller trees and other vegetation that survive pine beetle invasions along waterways increase their uptake of nitrate, a common disturbance-related pollutant. While logging or damaging storms can drive stream nitrate concentrations up by 400 percent for multiple years, the team found no significant increase in the nitrate concentrations following extensive pine beetle tree mortality in a number of Colorado study areas.

“We found that the beetles do not disturb watersheds in the same way as logging and severe storms,” said Lewis, interim director of CU’s Cooperative Institute for Research in Environmental Sciences. “They leave behind smaller trees and other understory vegetation, which compensate for the loss of larger pine trees by taking up additional nitrate from the system. Beetle-kill conditions are a good benchmark for the protection of sub-canopy vegetation to preserve water quality during forest management activities.”

....“The U.S. Forest Service and other agencies have established harvesting practices that greatly mitigate damage to forests caused by logging, and they deserve credit for that,” said Lewis. “But this study shows just how important the survival of smaller trees and understory vegetation can be to stream water quality.”

In waterways adjacent to healthy pine forests, concentrations of nitrate is generally far lower than in rivers on the plains in the West like the South Platte, said Lewis. Nitrate pollution is caused by agricultural runoff from populated areas and by permitted discharges of treated effluent from water treatment facilities....

Fog at the treeline in Rocky Mountain State Park, shot by Michael Gäbler, Wikimedia Commons, under the Creative Commons Attribution 3.0 Unported license

Pythons, lionfish and now willow invade Florida's waterways

University of Central Florida: Foreign invaders such as pythons and lionfish are not the only threats to Florida’s natural habitat. The native Carolina Willow is also starting to strangle portions of the St. Johns River.

Biologists at the University of Central Florida recently completed a study that shows this slender tree once used by Native Americans for medicinal purposes, may  be thriving because of water-management projects initiated in the 1950s. Canals were built to control  runoff and provide water for agriculture. The unintended consequence — stable water levels — allowed Carolina Willow to spread and thrive.

They now cover thousands of acres. Willows form impenetrable thickets that prevent boating and eliminate duck habitat. Willow thickets also use tremendous amounts of water, leaving less available for wildlife and people. The findings were published today in Restoration Ecology,  the peer-reviewed journal of the Society for Ecological Restoration. The St. Johns Water Management District funded the study.

While the trees previously were kept in check by natural annual flooding, they can now be found thriving in wetlands, swamps and marshes. Some trees grow as tall as 35 feet. The leaves of the tree contain salicin, which is the compound behind the pain-relieving effect of salicylic acid found in aspirin.

UCF professors Pedro F. Quintana-Ascencio and John Fauth worked with Kimberli Ponzio and Dianne Hall, scientists from the St. Johns River Water Management District, to run experiments that found ways to control the willow, which is taking over marshes in the upper St. Johns River basin....

St. John's River near Orange City, Florida, shot by Mwanner, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Tropical trees are largest emitter of methane in their ecosystem

The Open University News: Researchers at The Open University have found that trees in Bornean rainforests emit more methane than any other element of the ecosystem, which provides a new understanding about sources of this powerful greenhouse gas from tropical ecosystems.

In a paper titled Trees are major conduits for methane egress from tropical forested wetlands by Dr Vincent Gauci and Sunitha Pangala, published in New Phytologist on 18 December, the researchers announced new findings which show that trees in tropical peat forests of Southeast Asia release more methane through their stems than is emitted from the soil surface.

Sunitha Pangala, final year PhD student at The Open University’s Centre for Earth, Planetary Space and Astronomical Research, and lead author on the paper said: "This is the first study to measure methane release from tree stems in tropical peat swamps and evaluate its importance at an ecosystem level. Our research establishes that trees in tropical peat swamps are the largest emission pathway of methane in that ecosystem."

Previously it was thought that methane was only emitted via diffusion and bubbles at the wetland surface. The team measured methane emissions from healthy tree stems in a tropical forested peatland in the upper Sebangau River catchment in Borneo. They found significant quantities of methane being released from the stems of seven of the eight tree species studied. They estimated up to 87% of the methane are released from tree stems, highlighting that the previous methane emission inventories of this ecosystem may have been severely underestimated.

"This work challenges our previous understanding of how these ecosystems exchange methane with the atmosphere and adds another piece to the tropical methane emission puzzle,” said Dr Vincent Gauci, Senior Lecturer, Earth Systems, and the project’s leader. "It further shows that for wet tropical forested ecosystems, the like of which span south America, Africa and southeast Asia, researchers may have been missing most of the methane emitted from these ecosystems if they neglected to measure tree stem emissions.”...

A 1859 rendering of Borneo

Canopy structure more important to climate than leaf nitrogen levels

Terra Daily via SPX: Claims that forest leaves rich in nitrogen may aid in reflecting infrared radiation - helping cool the atmosphere - have been challenged by new research that shows that the structure of tree canopies is a more important factor in infrared reflection. Recent studies have noticed a strong positive correlation between the concentration of nitrogen in forests and infrared reflectance measured from aircraft and satellites.

Some scientists have suggested this demonstrates a previously overlooked role for nitrogen in regulating the earth's climate system.

However, a new paper in Proceedings of the National Academy of Sciences, shows that the apparent relationship between leaves' nitrogen levels and infrared reflection is spurious and it is in fact the structure of forest canopies (the spatial arrangement of the leaves) that determines their ability to reflect infrared light.

The authors, including Professor Philip Lewis and Dr Mathias Disney (UCL Geography), show that the richer in nitrogen individual leaves are the worse at reflecting infrared radiation they become.

However, the complex arrangements of trees with radically different arrangements of leaves within a forest can act to mask this effect, making it appear as if higher levels of leaf nitrogen are leading to increased infrared reflection....

A tree canopy in Sri Lanka's Sinharaja Forest Reserve, shot by Chamal N, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license

Drought-stressed trees face race to adapt

CNN: Scientists have known for some time that climate change and the impacts of longer droughts and higher temperatures could pose a problem for forests. But many thought it would only affect a minority of trees, perhaps just those in extremely arid regions.

However, new research is showing that a large majority of tree species around the world are operating on the brink of collapse. If the predicted pace of climate change continues, many may not be able to adapt in time and large numbers could die-off.

The authors of the study, whose findings were published in the scientific journal Nature, looked at 226 different tree species from 81 sites around the world, covering the full range of climatic conditions, from Mediterranean-type arid to the tropical Amazon rainforest.

They found that 70% of the trees studied adapt closely to the local environment, whether arid or tropical, absorbing just enough water in order to survive, but leaving them highly vulnerable to minor shifts in rainfall and drought stress.

"We thought that in the dry areas, plants would have adapted to survive more than ones growing in the wet, but we found they were all equally vulnerable. It was a big surprise," says Steven Jansen, from Germany's Ulm University and co-author of the study.

In periods of drought, the vascular network (xylem) distributing water and nutrients around the tree develops air bubbles which hinder the passage of water. As drought stress increases, these blockages, or "embolisms," accumulate eventually causing the tree to dry out and die....

Tree rings shot by Arpingstone, public domain

Ugandan communities plant trees to avert disaster

British Red Cross: The Red Cross has responded to a call from the Ugandan Ministry of Disaster Preparedness to provide 50,000 tree seedlings, which will help reforest parts of the Mount Elgon region.

The tree-planting project is part of a new Uganda Red Cross programme, launched in September 2012, to reduce the impact of disasters in the Elgon region. The majority of families depend on the land for their survival, putting pressure on natural resources.  Environmental degradation in this region is one of the factors causing more frequent floods and landslides over the last few years.

Karen Peachey, British Red Cross representative in east Africa, said: “Such disasters are only going to become a greater threat due to a rapidly growing population, continuing environmental degradation and climate change, which is predicted to increase both the dry spells and intense rains. The programme, which is supported by the British Red Cross, will help communities be better prepared, saving both lives and livelihoods.”

The Uganda Red Cross is helping 30 communities in the districts of Bududa, Bulambuli, Manafwa and Bukedea. William Kimanai, a 34-year old community volunteer in Wanga village, Bulambuli district, said: “We’ve been given a number of tree species including mangoes, guavas, oranges and eucalyptus. The trees conserve moisture and that is why we plant them along the river banks. We encourage every household member to plant at least three trees.”...

Mount Elgon, shot by Kristina Just, Wikimedia Commons via Flickr, under the Creative Commons Attribution-Share Alike 2.0 Generic license