10 December 2015, Science Daily, Trees either hunker down or press on in a drying and warming western US climate. In the face of adverse conditions, people might feel tempted by two radically different options — hunker down and wait for conditions to improve, or press on and hope for the best. It would seem that trees employ similar options when the climate turns dry and hot. Two University of Washington researchers have uncovered details of the radically divergent strategies that two common tree species employ to cope with drought in southwestern Colorado. As they report in a new paper in the journal Global Change Biology, one tree species shuts down production and conserves water, while the other alters its physiology to continue growing and using water. As the entire western United States becomes warmer and drier through human-made climate change, these findings shed light on how woody plants may confront twin scourges of less water and hot weather. The authors, UW biology graduate student Leander Anderegg and biology professor Janneke Hille Ris Lambers, wanted to understand if different tree species employ similar coping strategies for drought, and how these strategies would affect their future ranges in a warmer and drier climate. They compared how two common tree species differ in terms of shape, growth rate and physiology across wet and dry portions of their native ranges. “We really wanted to identify the entire suite of strategies that a plant can use to grow in drier environments, as well as which of these strategies each tree would employ,” said Hille Ris Lambers. Read more here
Tag Archives: forest response
24 November 2015, Climate News Network, Trees face global extinction threat. Field scientists warn that damage being done to the Amazon rainforest indicates that most of the world’s 40,000 tropical tree species now qualify as being at risk. More than half of all tree species in the Amazon forest could be at risk of extinction, according to new research. There are at least 15,000 species of tree in and around the Amazon basin and the Guiana Shield. At the lowest estimate, 36% are at risk, but the proportion under threat could also be as high as 57%. And since the Amazon rainforest is one of the planet’s richest habitats, and since what is true for one tropical great forest must apply to others, the research suggests that the number of threatened plant species on the planet could rise by 22%. Tropical trees worldwide number more than 40,000 species, and most of these may qualify as being to some degree threatened. Deforestation maps Hans ter Steege, research fellow at the Naturalis Biodiversity Centre in the Netherlands, and 157 colleagues from 21 countries report in Science Advances journal that they started with data from 1,485 forest inventories and measurements of species density from more than 1,600 plots of forest made across the Amazon region. They matched the information with maps of deforestation happening right now, or projected to happen, and then used statistical methods to make a range of estimates of the numbers of species at risk. The forests of the Amazon have already lost 12% of their original extent. By 2050, they could have lost at least another 9%, and perhaps as much as 28%. The forests are at risk from invasion by people hungry for land, and exploitation for mining and dam construction, as well as fire, drought and climate change. Read More here
28 October 2015, Climate News Network, Rise in wildfires depletes forests’ carbon store. As the world warms, the increasing hazard of forest fires is dangerously tilting trees’ carbon storage balance from positive to negative in some regions of Alaska. In a warming world, forest fires could be about to put more carbon dioxide into the atmosphere than the trees absorb. New research by US scientists looked at decades of wildfire incidence in Alaska, and they have found that at least one region is now a net exporter of carbon. This is a reversal of the normal arrangements, whereby trees photosynthesise tissue from the carbon dioxide in the atmosphere. As they absorb carbon, they sequester it in roots, timber and leaves, and then in leaf litter in the forest soils. Fire is a natural hazard, and some geographical zones –the Mediterranean, the US southwest, and Australia – are adapted to periodic fire. But as the planet warms, there have been increasing levels of fire even in therainforests of the Amazon and in the boreal forests of the near-Arctic. Read More here
22 October 2015, Science Daily, Measuring the impacts of severe wildfires in the Arctic. Based on the number of acres burned, 2015 is shaping up to be the second most extreme fire year during the past decade in North America’s boreal region. Historically, the area has had one or fewer extreme fire years per decade. This season, 15 million acres burned in Alaska and Canada, according Northern Arizona University’s Michelle Mack, researcher and biological sciences professor, who is leading a NASA-funded project to measure the severe fire impacts in North America. “In the boreal region, there is a thick organic layer on the surface comprised of litter and soil, that in some cases is hundreds to thousands of years old,” Mack said. “Will more fires and hotter fires burn that layer and release it to the atmosphere and how deep will it burn into the soil?” These questions are part of NASA’s $100 million dollar, 10 year project called Arctic Boreal Vulnerability Experiment, also known as ABoVE. The experiment seeks to understand the vulnerability and resilience in the Arctic, where climate change is most pronounced and rapidly unfolding. Mack serves on the project’s international science team tasked with implementing the field campaign. Read More here