Ecosystems

Which trees face death in drought?
April 19, 2016 07:19 AM - University of Utah

Two hundred-twenty-five million trees dead in the southwest in a 2002 drought. Three hundred million trees in Texas in 2011. Twelve million this past year in California.  Throughout the world, large numbers of trees are dying in extreme heat and drought events. Because mass die-offs can have critical consequences for the future of forests and the future of Earth’s climate, scientists are trying to understand how a warming climate could affect how often tree mortality events occur – and how severe they could become.

Clear cutting and its influence on carbon storage
April 15, 2016 07:28 PM - Dartmouth College via ScienceDaily.

lear-cutting loosens up carbon stored in forest soils, increasing the chances it will return to the atmosphere as carbon dioxide and contribute to climate change, a Dartmouth College study shows.

The findings appear in the journal Soil Science.

Soil is the world's largest terrestrial carbon pool. In northern hardwood forests in the United States, mineral soil pools store up to 50 percent of total ecosystem carbon. Logging and other land-use changes are a major cause of soil carbon release, but there has been recent interest to further understand soil carbon dynamics in forested ecosystems after logging. This is of particular importance in the northeastern U.S. because of the great potential for the use of biomass as part of a diversified renewable energy portfolio.

The Dartmouth researchers explored whether clear-cutting changes the strength of the chemical bonds of carbon stored in mineral soils in hardwood forests in the northeastern United States. Clear-cutting involves harvesting all timber from a site at once rather than selectively culling mature trees. Carbon is stored in soil by binding only to certain soil structures.

The researchers collected soils from recently clear-cut forests and from older forests, and pulled carbon from the soil in a sequence of gentle to stronger extractions. The results showed that mature forest stands stored significantly more soil organic carbon in strongly mineral-bound and stable carbon pools than did soils from cut stands.

Moths in cities have learned to avoid man-made light
April 13, 2016 11:35 AM - UNIVERSITY OF BASEL via EurekAlert

The globally increasing light pollution has negative effects on organisms and entire ecosystems. The consequences are especially hard on nocturnal insects, since their attraction to artificial light sources generally ends fatal. A new study by Swiss zoologists from the Universities of Basel and Zurich now shows that urban moths have learned to avoid light. The journal Biology Letters has published their results.

Some insects are attracted by light while others shy away from it. Proverbial is the attraction light has on moths. Street lamps and other artificial light sources often become death traps for nocturnal insects such as moths. Either they die through direct burning or through increased exposure to predators. Mortality of urban insects can thus be 40- to 100- fold higher than in rural populations.

 

Reducing food waste could help mitigate climate change
April 11, 2016 07:33 AM - Potsdam Institute for Climate Impact Research

About a tenth of overall global greenhouse-gas emissions from agriculture could be traced back to food waste by mid-century, a new study shows. A team from the Potsdam Institute for Climate Impact Research for the first time provides comprehensive food loss projections for countries around the world while also calculating the associated emissions. Currently, one third of global food production never finds its way onto our plates. This share will increase drastically, if emerging countries like China and India adopt Western nutrition lifestyles, the analyses shows. Reducing food waste would offer the chance to ensure food security, which is well known. Yet at the same time it could help mitigate dangerous climate change.

The North Pole had ice-free summers millions of years ago
April 8, 2016 07:22 AM - Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research via ScienceDaily.

An international team of scientists led by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI) have managed to open a new window into the climate history of the Arctic Ocean. Using unique sediment samples from the Lomonosov Ridge, the researchers found that six to ten million years ago the central Arctic was completely ice-free during summer and sea-surface temperature reached values of 4 to 9 degrees Celsius. In spring, autumn and winter, however, the ocean was covered by sea ice of variable extent, the scientists explain in the current issue of the journal Nature Communications. These new findings from the Arctic region provide new benchmarks for groundtruthing global climate reconstructions and modelling.

The researchers had recovered these unique sediment samples during an expedition with Germany's research icebreaker RV Polarstern in summer of 2014. "The Arctic sea ice is a very critical and sensitive component in the global climate system. It is therefore important to better understand the processes controlling present and past changes in sea ice. In this context, one of our expedition's aims was to recover long sediment cores from the central Arctic, that can be used to reconstruct the history of the ocean's sea ice cover throughout the past 50 million years. Until recently, only a very few cores representing such old sediments were available, and, thus, our knowledge of the Arctic climate and sea ice cover several millions of year ago is still very limited," Prof. Dr. Ruediger Stein, AWI geologist, expedition leader and lead author of the study, explains.

 

Using moss as a bioindicator of air pollution
April 8, 2016 07:16 AM - USDA Forest Service via EurekAlert!

Moss growing on urban trees is a useful bio-indicator of cadmium air pollution in Portland, Oregon, a U.S. Forest Service Pacific Northwest Research Station-led study has found. The work--the first to use moss to generate a rigorous and detailed map of air pollution in a U.S. city--is published online in the journal Science of the Total Environment.

Earth's soils could play key role in locking away greenhouse gases
April 7, 2016 06:51 AM - University of Edinburgh via EurekAlert!

The world's soils could store an extra 8 billion tonnes of greenhouse gases, helping to limit the impacts of climate change, research suggests.

Adopting the latest technologies and sustainable land use practices on a global scale could allow more emissions to be stored in farmland and natural wild spaces, the study shows. 

Illegal gold mining in Brazil exposing indigenous peoples to high levels of mercury
April 5, 2016 11:52 AM - Sarina Kidd / Survival International, The Ecologist

Illegal gold mining in the Amazon has a devastating effect on indigenous peoples, writes Sarina Kidd. First the miners bring disease, deforestation and even murder. Then long after they have gone, communities are left to suffer deadly mercury poisoning. Now the UN has been called on to intervene.

In Brazil, new statistics reveal alarming rates of mercury poisoning amongst the Yanomami and Yekuana. 90% of Indians in one community are severely affected, with levels far above that recommended by the WHO.

Mercury poisoning is devastating tribal peoples across Amazonia, Survival International has warned.

 

NASA examines El Nino's impact on ocean's food source
April 4, 2016 07:46 PM - NASA/Goddard Space Flight Center

El Niño years can have a big impact on the littlest plants in the ocean, and NASA scientists are studying the relationship between the two. In El Niño years, huge masses of warm water – equivalent to about half of the volume of the Mediterranean Sea – slosh east across the Pacific Ocean towards South America. While this warm water changes storm systems in the atmosphere, it also has an impact below the ocean’s surface. These impacts, which researchers can visualize with satellite data, can ripple up the food chain to fisheries and the livelihoods of fishermen.

Snowshoe hare range moving northward following retreating snow cover
March 31, 2016 07:52 AM - University of Wisconsin-Madison via ScienceDaily

If there is an animal emblematic of the northern winter, it is the snowshoe hare.

A forest dweller, the snowshoe hare is named for its big feet, which allow it to skitter over deep snow to escape lynx, coyotes and other predators. It changes color with the seasons, assuming a snow-white fur coat for winter camouflage.

But a changing climate and reduced snow cover across the north is squeezing the animal out of its historic range, according to a new study by researchers at the University of Wisconsin-Madison. Writing in the current (March 30, 2016) Proceedings of the Royal Society B, the Wisconsin researchers report that the range of the hare in Wisconsin is creeping north by about five and a half miles per decade, closely tracking the diminishing snow cover the animal requires to be successful.

 

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