29 August 2015, Climate News Network, Climate models may misjudge soils’ carbon emissions. How soil organisms cope with decaying vegetation is much less certain than climate models suppose, researchers say, and carbon emission estimates may be wrong. Some of the microscopic creatures which live in the soil are able to digest dead plants and trees, turning their contents into gas and minerals. But researchers say their work show that our understanding of how organic material is decomposed is fundamentally wrong, calling into question some current climate models. The researchers, from Lund University, Sweden, and the University of New Hampshire, USA, have published their study in the journal Ecological Monographs. They say it means that climate models which include micro-organisms in their estimates of future climate change must be reconsidered. When plants or trees die, their leaves and branches fall to the ground and the organic matter which is absorbed by the soil is then decomposed, mainly by the activity of fungi and bacteria, which convert the dead materials into the main greenhouse gas, carbon dioxide, and mineral nutrients. Until now, the Lund team says, scientists had thought that high-quality organic materials, such as leaves that are rich in soluble sugars, were mainly decomposed by bacteria, leaving the lower-quality matter, like cellulose and lignin, to be broken down mainly by fungi. Expectations confounded. Previous research has suggested that organic material decomposed by fungi results in less CO2 and nutrient leakage compared with matter decomposed by bacteria. This is important for the climate models in use today, as any change in the loss of CO2 and mineral nitrogen would alter the soil’s contribution to greenhouse gases and eutrophication, the process in which the release of excessive chemical pollution causes algal blooms in watercourses. Read More here
Tag Archives: forest response
17 August, Climate News Network, Andes’ migrating trees are moving towards extinction. Highland tree species in the Andes are decreasing as global warming caused by greenhouse gas emissions forces lowland varieties to move upwards into cooler climes. Scientists have known for years that, in a warming world, many living things try to move uphill to seek survival where the air is cooler. But new research provides a dire warning of the risks for those unable to move fast enough. Unlike animals, trees and other sorts of vegetation cannot move quickly to escape the heat. And for some of them, it seems, there is no survival option available. They simply die. A study published in the Proceedings of the National Academy of Sciences reports that the number of highland tree species in the Andes mountains of South America is decreasing as lowland trees move up the slope to avoid the rising temperatures and changing rainfall patterns. The results suggest that tropical tree species in the region are at risk of extinction because of the intensification of warming, caused by emissions of greenhouse gases from human activities. Can’t escape. “The effects of climate change are everywhere – you can’t escape it,” says Kenneth J. Feeley, a researcher in the Department of Biological Sciences and International Centre for Tropical Botany at Florida International University. “Some people hold the notion that the Amazon is an isolated and pristine ecosystem, immune to disturbances. We need to change our mindset and open our eyes to the fact that, even in the middle of the Amazon or the remote Andes mountains, species are at risk. Read More here
1 August 2015, Climate Network News, Wildfire threat spreads across warming world. As climate change warms the world vegetation dries, rainfall patterns waver and the threat of wildfire spreads. Wildfire – nature’s way of turning fallen vegetation into the next season’s nutrients – is a growing hazard. In the last 35 years, the wildfire season has grown longer by a fifth, and wildfire is now a threat to one fourth of all the plant-covered land on the planet. US researchers report in Nature Communications that since 1970 the number of days without rain has increased by well over one day every decade. William Jolly of the US Forest Service in Missoula, Montana and colleagues say they examined the fire season worldwide for the study period, taking into consideration all the factors that are used to calculate fire hazard: wind, humidity and temperature, as well as rainfall levels. They found that the combined changes in the surface weather have meant that the fire season has increased so far by 18.7%. Worldwide, wildfires sear, scorch or incinerate about 350 million hectares of ground cover every year. Changes in the rainfall patterns were a factor, with the number of rain-free days increasing by 1.31 days per decade. The season of smoke and cinders and smouldering stumps had been extended almost everywhere. Read More here
30 July 2015, Science Daily, Drought’s lasting impact on forests. Forests across the planet take years to rebound from drought, storing far less carbon dioxide than widely assumed in climate models. In the virtual worlds of climate modeling, forests and other vegetation are assumed to bounce back quickly from extreme drought. But that assumption is far off the mark, according to a new study of drought impacts at forest sites worldwide. Living trees took an average of two to four years to recover and resume normal growth rates after droughts ended, researchers report today in the journal Science. “This really matters because in the future droughts are expected to increase in frequency and severity due to climate change,” says lead author William R.L. Anderegg, an assistant professor of biology at the University of Utah. “Some forests could be in a race to recover before the next drought strikes.” Forest trees play a big role in buffering the impact of human-induced climate change by removing massive amounts of carbon dioxide emissions from the atmosphere and incorporating the carbon into woody tissues. The finding that drought stress sets back tree growth for years suggests that Earth’s forests are capable of storing less carbon than climate models have calculated. Read More here