. | . |
Drought-affected trees die from hydraulic failure and carbon starvation by Staff Writers Sydney, Australia (SPX) Aug 09, 2017
The report finds that hydraulic failure, which is the inability of a plant to move water from roots to leaves to be almost universally present when trees died, while carbon starvation was a contributing factor roughly half of the time. "Droughts are increasing in frequency and severity, and their impact on plants and humans, is becoming more intense," says research co-author, Dr Melanie Zeppel of Sydney University's Charles Perkins Centre. "The discovery of how droughts cause death in trees, regardless of tree type, will let us make better regional-scale predictions of the effects of droughts on forests." The dramatic impacts of tree die-back on water and carbon cycles, as well as bush fire intensity and timing, have been observed in recent years in south-east Australia, Dr Zeppel noted. As the number of hot droughts increases globally, scientists are looking to make more consistent predictions of what will happen to plants and vegetation in the future. This matters for models used to predict climate change because plants take up a big portion of the carbon dioxide humans pump in the atmosphere. Therefore, the effect of tree death and die-off, as observed globally in recent decades, could affect the rate at which climate changes. "Current global vegetation models have a hard time producing consistent and accurate estimates of plant carbon dioxide-uptake, and their predictions vary widely based on the assumptions they use about how plants respond to climate," says Dr Zeppel. "Trees and forests are particularly important because they take up and store a lot of this carbon dioxide, and also affect their environment in other ways." "Understanding drought is critical to managing our nation's forests," says Lina Patino, section head of the National Science Foundation's Division of Earth Sciences, which funded the study. "This research will help us more accurately predict how different plant species respond to different types of environmental stress such as drought, insect damage or disease." The paper's lead author, Dr Henry Adams at Oklahoma State University explains that 99 percent of the water moving through a tree is used to keep stomata open, the pores that let in carbon dioxide, allowing it to carry out photosynthesis. Trees respond to the stress of drought by closing those pores that let in carbon dioxide. At that point, they need to rely on their stored sugars and starches to stay alive, and could die from carbon starvation if they run out before the drought is over. On the other hand, if the tree loses too much water too quickly, an air bubble (embolism) will form and the tree has hydraulic failure, it cannot transport water from the roots to the leaves, which becomes lethal as the whole tree dries out. Adams and his colleagues saw that in many cases, both carbon starvation and hydraulic failure appeared to occur as trees died. This makes sense, because the stored sugars and starches that could be reduced in carbon starvation are also important for preventing hydraulic failure. When converted to sugar, these can act as "osmoprotectants," increasing the tree's ability to hold on to its water. "It's kind of like antifreeze in a car that keeps the engine from overheating," Adams says.
Jena, Germany (SPX) Aug 07, 2017 The first review of the global impact of humans on tropical forests in the ancient past shows that humans have been altering these environments for at least 45,000 years. This counters the view that tropical forests were pristine natural environments prior to modern agriculture and industrialization. The study, published in Nature Plants, found that humans have in fact been having a dramat ... read more Related Links University of Sydney Forestry News - Global and Local News, Science and Application
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |