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Shengli Tao, Qinghua Guo, Chao Li, Zhiheng Wang, Jingyun Fang
Forest canopy height is an important indicator of forest biomass, species diversity, and other ecosystem functions; however, the climatic determinants that underlie its global patterns have not been fully explored. Using satellite LiDAR-derived forest canopy heights and field measurements of the world's giant trees, combined with climate indices, we evaluated the global patterns and determinants of forest canopy height. The mean canopy height was highest in tropical regions, but tall forests (>50 m) occur at various latitudes...
December 2016: Ecology
Leah M Mungai, Sieglinde Snapp, Joseph P Messina, Regis Chikowo, Alex Smith, Erin Anders, Robert B Richardson, Guiying Li
The sustainable intensification of African agriculture is gaining momentum with the compelling need to increase food and agricultural production. In Southern Africa, smallholder farming systems are predominately maize-based and subject to erratic climatic conditions. Farmer crop and soil management decisions are influenced by a plethora of complex factors such as market access resource availability, social relations, environment, and various messages on sustainable farming practices. Such factors pose barriers to increasing sustainable intensification in Africa...
2016: Frontiers in Plant Science
Prashant Prakash Jambhulkar, Nitiprasad Jambhulkar, Madanlal Meghwal, Gauri Shankar Ameta
Early blight of tomato caused by Alternaria solani, is responsible for severe yield losses in tomato. The conidia survive on soil surface and old dry lower leaves of the plant and spread when suitable climatic conditions are available. Macroclimatic study reveals that highest inoculum concentration of Alternaria spores appeared in May 2012 to 2013 and lowest concentration during January 2012 to 2013. High night temperature positively correlated and significantly (P < 0.01) involved in conidial spore dispersal and low relative humidity (RH) displayed significant (P < 0...
December 2016: Plant Pathology Journal
Qianfeng Wang, Jianjun Wu, Xiaohan Li, Hongkui Zhou, Jianhua Yang, Guangpo Geng, Xueli An, Leizhen Liu, Zhenghong Tang
The quantitative evaluation of the impact of drought on crop yield is one of the most important aspects in agricultural water resource management. To assess the impact of drought on wheat yield, the Environmental Policy Integrated Climate (EPIC) crop growth model and daily Standardized Precipitation Evapotranspiration Index (SPEI), which is based on daily meteorological data, are adopted in the Huang Huai Hai Plain. The winter wheat crop yields are estimated at 28 stations, after calibrating the cultivar coefficients based on the experimental site data, and SPEI data was taken 11 times across the growth season from 1981 to 2010...
November 25, 2016: International Journal of Biometeorology
Rafael Poyatos, Víctor Granda, Roberto Molowny-Horas, Maurizio Mencuccini, Kathy Steppe, Jordi Martínez-Vilalta
Plant transpiration is the main evaporative flux from terrestrial ecosystems; it controls land surface energy balance, determines catchment hydrological responses and influences regional and global climate. Transpiration regulation by plants is a key (and still not completely understood) process that underlies vegetation drought responses and land evaporative fluxes under global change scenarios. Thermometric methods of sap flow measurement have now been widely used to quantify whole-plant and stand transpiration in forests, shrublands and orchards around the world...
November 23, 2016: Tree Physiology
Lluvia A Chávez-Ambriz, Alejandro Hernández-Morales, José A Cabrera-Luna, Laura Luna-Martínez, Juan R Pacheco-Aguilar
Cacti are the most representative vegetation of arid zones in Mexico where rainfall is scarce, evapotranspiration is high and soil fertility is low. Plants have developed physiological strategies such as the association with microorganisms in the rhizosphere zone to increase nutrient uptake. In the present work, four bacterial isolates from the rhizosphere of Mammillaria magnimamma and Coryphantha radians were obtained and named as QAP3, QAP19, QAP22 and QAP24, and were genetically identified as belonging to the genus Bacillus, exhibiting in vitro biochemical properties such as phosphate solubilization, indoleacetic acid production and ACC deaminase activity related to plant growth promotion, which was tested by inoculating M...
November 18, 2016: Revista Argentina de Microbiología
Gerald A Meehl, Claudia Tebaldi, Dennis Adams-Smith
Observed temperature extremes over the continental United States can be represented by the ratio of daily record high temperatures to daily record low minimum temperatures, and this ratio has increased to a value of about 2 to 1, averaged over the first decade of the 21st century, albeit with large interannual variability. Two different versions of a global coupled climate model (CCSM4), as well as 23 other coupled model intercomparison project phase 5 (CMIP5) models, show larger values of this ratio than observations, mainly as a result of greater numbers of record highs since the 1980s compared with observations...
November 21, 2016: Proceedings of the National Academy of Sciences of the United States of America
E W Slessarev, Y Lin, N L Bingham, J E Johnson, Y Dai, J P Schimel, O A Chadwick
Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility-rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy...
November 21, 2016: Nature
Zhuanfang Fred Zhang, Christopher E Strickland, Steven O Link
Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. After establishing a set of design and performance objectives, a package of design solutions was developed for 1000-year surface barriers over nuclear waste sites. The Prototype Hanford Barrier (PHB) was then constructed in 1994 in the field over an existing waste site as a demonstration...
November 18, 2016: Journal of Environmental Management
Paul E Abraham, Hengfu Yin, Anne M Borland, Deborah Weighill, Sung Don Lim, Henrique Cestari De Paoli, Nancy Engle, Piet C Jones, Ryan Agh, David J Weston, Stan D Wullschleger, Timothy Tschaplinski, Daniel Jacobson, John C Cushman, Robert L Hettich, Gerald A Tuskan, Xiaohan Yang
Already a proven mechanism for drought resilience, crassulacean acid metabolism (CAM) is a specialized type of photosynthesis that maximizes water-use efficiency by means of an inverse (compared to C3 and C4 photosynthesis) day/night pattern of stomatal closure/opening to shift CO2 uptake to the night, when evapotranspiration rates are low. A systems-level understanding of temporal molecular and metabolic controls is needed to define the cellular behaviour underpinning CAM. Here, we report high-resolution temporal behaviours of transcript, protein and metabolite abundances across a CAM diel cycle and, where applicable, compare the observations to the well-established C3 model plant Arabidopsis...
November 21, 2016: Nature Plants
Inmaculada Garrido, David Uriarte, Marcos Hernández, José Luis Llerena, María Esperanza Valdés, Francisco Espinosa
A study was made of how water status (rainfed vs. irrigated) and crop load (no cluster thinning vs. cluster thinning) can together affect the grapes of Vitis vinifera cv. Tempranillo vines growing in a semiarid zone of Extremadura (Spain). The grapes were monitored at different stages of ripening, measuring the peroxidase (POX) and superoxide dismutase (SOD) antioxidant activities and the phenolic content (flavonoids and phenylpropanoids), together with other parameters. The irrigation regime was adjusted to provide 100% of crop evapotranspiration (ETc)...
November 17, 2016: International Journal of Molecular Sciences
Jörg Schaller, Jonas Schoelynck, Mike Murray-Hudson, Patrick J Frings, Dimitri van Pelt, Tilo Hegewald, Keotshephile Mosimane, Mangaliso Gondwe, Piotr Wolski, Patrick Meire, Eric Struyf
Wetlands fed by rivers can be a sink for elements depending on elemental concentrations, wetland hydrology, geochemistry, vegetation and climate. In the case of the Okavango Delta, northern Botswana, the outflow discharge is a small fraction (2-5%) of the inflow. This has strong potential consequences for the Delta, as it strongly affects element cycling and storage within the Delta. We estimated the inputs, behaviour and distribution of multiple elements along a longitudinal transect within the Okavango Delta, to show potential effects of retention mechanisms of different elements...
December 0: Environmental Monitoring and Assessment
Michele Faralli, Ivan G Grove, Martin C Hare, Peter S Kettlewell, Fabio Fiorani
The productivity of many important crops is significantly threatened by water shortage and the elevated atmospheric CO2 can significantly interact with physiological processes and crop responses to drought. We examined the effects of three different CO2 concentrations (historical ~300 ppm, ambient ~400 ppm and elevated ~700 ppm) on physiological traits of oilseed rape (Brassica napus L.) seedlings subjected to well-watered and reduced water availability. Our data show i) that, as expected, increasing CO2 level positively modulates leaf photosynthetic traits, leaf water-use efficiency and growth under non-stressed conditions although a pronounced acclimation of photosynthesis to elevated CO2 occurred; ii) that the predicted elevated CO2 concentration does not reduce total evapotranspiration under drought when compared to the present (400 ppm) and historical (300 ppm) concentrations because of a larger leaf area that does not buffer transpiration; iii) that accordingly the physiological traits analysed decreased similarly under stress for all CO2 concentrations...
November 18, 2016: Plant, Cell & Environment
Alexandru Milcu, Werner Eugster, Dörte Bachmann, Marcus Guderle, Christiane Roscher, Annette Gockele, Damien Landais, Olivier Ravel, Arthur Gessler, Markus Lange, Anne Ebeling, Wolfgang W Weisser, Jacques Roy, Anke Hildebrandt, Nina Buchmann
The impact of species richness and functional diversity of plants on ecosystem water vapor fluxes has been little investigated. To address this knowledge gap, we combined a lysimeter setup in a controlled environment facility (Ecotron) with large ecosystem samples/monoliths originating from a long-term biodiversity experiment (The Jena Experiment) and a modeling approach. Our goals were (1) quantifying the impact of plant species richness (four vs. 16 species) on day- and nighttime ecosystem water vapor fluxes; (2) partitioning ecosystem evapotranspiration into evaporation and plant transpiration using the Shuttleworth and Wallace (SW) energy partitioning model; and (3) identifying the most parsimonious predictors of water vapor fluxes using plant functional-trait-based metrics such as functional diversity and community weighted means...
August 2016: Ecology
Kyle A Palmquist, Daniel R Schlaepfer, John B Bradford, William K Lauenroth
In the coming century, climate change is projected to impact precipitation and temperature regimes worldwide, with especially large effects in drylands. We use big sagebrush ecosystems as a model dryland ecosystem to explore the impacts of altered climate on ecohydrology and the implications of those changes for big sagebrush plant communities using output from 10 Global Circulation Models (GCMs) for two representative concentration pathways (RCPs). We ask: (1) What is the magnitude of variability in future temperature and precipitation regimes among GCMs and RCPs for big sagebrush ecosystems, and (2) How will altered climate and uncertainty in climate forecasts influence key aspects of big sagebrush water balance? We explored these questions across 1980-2010, 2030-2060, and 2070-2100 to determine how changes in water balance might develop through the 21st century...
September 2016: Ecology
Bingfang Wu, Shufu Liu, Weiwei Zhu, Mingzhao Yu, Nana Yan, Qiang Xing
Sunshine duration is an important variable that is widely used in atmospheric energy balance studies, analysis of the thermal loadings on buildings, climate research, and the evaluation of agricultural resources. In most cases, it is calculated using an interpolation method based on regional-scale meteorological data from field stations. Accurate values in the field are difficult to obtain without ground measurements. In this paper, a satellite-based method to estimate sunshine duration is introduced and applied over the Heihe River Basin...
November 4, 2016: Sensors
Ying Hou, Bo Li, Felix Müller, Weiping Chen
Watersheds provide multiple ecosystem services. Ecosystem service assessment is a promising approach to investigate human-environment interaction at the watershed scale. The spatial characteristics of ecosystem services are closely related to land use statuses in human-dominated watersheds. This study aims to investigate the effects of land use on the spatial variations of ecosystem services at the Dianchi Lake watershed in Southwest China. We investigated the spatial variations of six ecosystem services-food supply, net primary productivity (NPP), habitat quality, evapotranspiration, water yield, and nitrogen retention...
December 0: Environmental Monitoring and Assessment
Jannik Heusinger, Stephan Weber
Green roofs are discussed as a promising type of green infrastructure to lower heat stress in cities. In order to enhance evaporative cooling, green roofs should ideally have similar Bowen ratio (β=sensible heat flux/latent heat flux) characteristics such as rural sites, especially during summer periods with high air temperatures. We use the eddy-covariance (EC) method to quantify the energy balance of an 8600m(2) extensive, non-irrigated green roof at the Berlin Brandenburg Airport, Germany over a full annual cycle...
January 15, 2017: Science of the Total Environment
David Helman, Itamar M Lensky, Dan Yakir, Yagil Osem
More frequent and intense droughts are projected during the next century, potentially changing the hydrological balances in many forested catchments. Although the impacts of droughts on forest functionality have been vastly studied, little attention has been given to studying the effect of droughts on forest hydrology. Here, we use the Budyko framework and two recently introduced Budyko metrics (deviation and elasticity) to study the changes in the water yields (rainfall minus evapotranspiration) of forested catchments following a climatic drought (2006-2010) in pine forests distributed along a rainfall gradient (P=280-820 mm y(-1) ) in the Eastern Mediterranean (aridity factor=0...
November 3, 2016: Global Change Biology
Long Wan, Jing Tong, Jinxing Zhou, Hongyan Guo, Ming Cui, Yuguo Liu, Like Ning, Fukai Tang
Over the past several decades, rocky desertification has led to severe ecological problems in karst areas in South China. After a rocky desertification treatment project was completed, the vegetation coverage changed greatly and, consequently, increased the ecology water consumption (approximately equal to the actual evapotranspiration) of the regional vegetation. Thus, it intensified the regional water stresses. This study explored the changes in the actual evapotranspiration (ETa) response to the vegetation coverage changes in the rocky desertification areas in South China based on the precipitation (P), potential evapotranspiration (ETp) and NDVI (the normalized difference vegetation index) datasets...
2016: PloS One
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