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  • 1
    Publication Date: 2013-01-22
    Description: Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions. Large-scale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security. Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975-1998), and drier, warmer conditions in the early twenty-first century (2000-2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUE(e): above-ground net primary production/evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUE(e) in drier years that increased significantly with drought to a maximum WUE(e) across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought--that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUE(e) may allow us to predict land-surface consequences as large regions become more arid, starting with water-limited, low-productivity grasslands.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ponce Campos, Guillermo E -- Moran, M Susan -- Huete, Alfredo -- Zhang, Yongguang -- Bresloff, Cynthia -- Huxman, Travis E -- Eamus, Derek -- Bosch, David D -- Buda, Anthony R -- Gunter, Stacey A -- Scalley, Tamara Heartsill -- Kitchen, Stanley G -- McClaran, Mitchel P -- McNab, W Henry -- Montoya, Diane S -- Morgan, Jack A -- Peters, Debra P C -- Sadler, E John -- Seyfried, Mark S -- Starks, Patrick J -- England -- Nature. 2013 Feb 21;494(7437):349-52. doi: 10.1038/nature11836. Epub 2013 Jan 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉USDA ARS Southwest Watershed Research, Tucson, Arizona 85719, USA. geponce@gmail.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23334410" target="_blank"〉PubMed〈/a〉
    Keywords: Climate Change/history/*statistics & numerical data ; Droughts/history/*statistics & numerical data ; *Ecosystem ; History, 20th Century ; History, 21st Century ; Plants/*metabolism ; Poaceae/metabolism ; Rain ; Trees/metabolism ; Water/*metabolism ; Water Cycle
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-06-23
    Description: Ecosystem respiration is the biotic conversion of organic carbon to carbon dioxide by all of the organisms in an ecosystem, including both consumers and primary producers. Respiration exhibits an exponential temperature dependence at the subcellular and individual levels, but at the ecosystem level respiration can be modified by many variables including community abundance and biomass, which vary substantially among ecosystems. Despite its importance for predicting the responses of the biosphere to climate change, it is as yet unknown whether the temperature dependence of ecosystem respiration varies systematically between aquatic and terrestrial environments. Here we use the largest database of respiratory measurements yet compiled to show that the sensitivity of ecosystem respiration to seasonal changes in temperature is remarkably similar for diverse environments encompassing lakes, rivers, estuaries, the open ocean and forested and non-forested terrestrial ecosystems, with an average activation energy similar to that of the respiratory complex (approximately 0.65 electronvolts (eV)). By contrast, annual ecosystem respiration shows a substantially greater temperature dependence across aquatic (approximately 0.65 eV) versus terrestrial ecosystems (approximately 0.32 eV) that span broad geographic gradients in temperature. Using a model derived from metabolic theory, these findings can be reconciled by similarities in the biochemical kinetics of metabolism at the subcellular level, and fundamental differences in the importance of other variables besides temperature-such as primary productivity and allochthonous carbon inputs-on the structure of aquatic and terrestrial biota at the community level.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yvon-Durocher, Gabriel -- Caffrey, Jane M -- Cescatti, Alessandro -- Dossena, Matteo -- del Giorgio, Paul -- Gasol, Josep M -- Montoya, Jose M -- Pumpanen, Jukka -- Staehr, Peter A -- Trimmer, Mark -- Woodward, Guy -- Allen, Andrew P -- England -- Nature. 2012 Jul 26;487(7408):472-6. doi: 10.1038/nature11205.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Biological & Chemical Sciences, Queen Mary University of London, London E1 4NS, UK. g.yvon-durocher@exeter.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22722862" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomass ; Biota ; Carbon/*metabolism ; Carbon Dioxide/*metabolism ; Cell Respiration ; Data Collection ; *Ecosystem ; *Global Warming ; Humans ; Kinetics ; Lakes ; Marine Biology ; *Oxygen Consumption ; Photosynthesis ; Rivers ; Seasons ; Seawater ; *Temperature ; Time Factors ; Trees/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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