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https://www.readbyqxmd.com/read/28432257/excess-diffuse-light-absorption-in-upper-mesophyll-limits-co2-drawdown-and-depresses-photosynthesis
#1
Jeffrey Mason Earles, Guillaume Théroux-Rancourt, Matthew E Gilbert, Andrew J McElrone, Craig Brodersen
In agricultural and natural systems, diffuse light can enhance plant primary productivity due to deeper penetration into and greater illumination of the entire canopy. However, for individual sun-grown leaves from three species, photosynthesis is actually less efficient under diffuse compared to direct light. Despite its potential impact on canopy-level productivity, the mechanism for this leaf-level 'diffuse light photosynthetic depression' effect is unknown. Here we investigate if the spatial distribution of light absorption relative to electron transport capacity in sun- and shade-grown H...
April 21, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28431185/the-effect-of-interspecific-variation-in-photosynthetic-plasticity-on-4-year-growth-rate-and-8-year-survival-of-understorey-tree-seedlings-in-response-to-gap-formations-in-a-cool-temperate-deciduous-forest
#2
Riichi Oguchi, Tsutom Hiura, Kouki Hikosaka
Gap formation increases the light intensity in the forest understorey. The growth responses of seedlings to the increase in light availability show interspecific variation, which is considered to promote biodiversity in forests. At the leaf level, some species increase their photosynthetic capacity in response to gap formation, whereas others do not. Here we address the question of whether the interspecific difference in the photosynthetic response results in the interspecific variation in the growth response...
April 19, 2017: Tree Physiology
https://www.readbyqxmd.com/read/28428865/competition-and-facilitation-structure-plant-communities-under-nurse-tree-canopies-in-extremely-stressful-environments
#3
Ali A Al-Namazi, Magdy I El-Bana, Stephen P Bonser
Nurse plant facilitation in stressful environments can produce an environment with relatively low stress under its canopy. These nurse plants may produce the conditions promoting intense competition between coexisting species under the canopy, and canopies may establish stress gradients, where stress increases toward the edge of the canopy. Competition and facilitation on these stress gradients may control species distributions in the communities under canopies. We tested the following predictions: (1) interactions between understory species shift from competition to facilitation in habitats experiencing increasing stress from the center to the edge of canopy of a nurse plant, and (2) species distributions in understory communities are controlled by competitive interactions at the center of canopy, and facilitation at the edge of the canopy...
April 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28428805/edible-dormice-glis-glis-avoid-areas-with-a-high-density-of-their-preferred-food-plant-the-european-beech
#4
Jessica S Cornils, Franz Hoelzl, Birgit Rotter, Claudia Bieber, Thomas Ruf
BACKGROUND: Numerous species, especially among rodents, are strongly affected by the availability of pulsed resources. The intermittent production of large seed crops in northern hemisphere tree species (e.g., beech Fagus spec.,oak Quercus spec., pine trees Pinus spec.) are prime examples of these resource pulses. Adult edible dormice are highly dependent on high energy seeds to maximize their reproductive output. For juvenile dormice the energy rich food is important to grow and fatten in a very short time period prior to hibernation...
2017: Frontiers in Zoology
https://www.readbyqxmd.com/read/28426175/differences-in-xylem-and-leaf-hydraulic-traits-explain-differences-in-drought-tolerance-among-mature-amazon-rainforest-trees
#5
Thomas L Powell, James K Wheeler, Alex A R de Oliveira, Antonio Carlos Lola da Costa, Scott R Saleska, Patrick Meir, Paul R Moorcroft
Considerable uncertainty surrounds the impacts of anthropogenic climate change on the composition and structure Amazon forests. Two large-scale ecosystem drought experiments in the eastern Brazilian Amazon observed increases in mortality rates among some tree species but not others; and therefore, the physiological traits underpinning these differential demographic responses were investigated. Xylem pressure at 50% conductivity (xylem-P50 ), leaf turgor loss point (TLP), cellular osmotic potential (πo ) and cellular bulk modulus of elasticity (ε), all traits mechanistically linked to drought tolerance, were measured on upper canopy branches and leaves of mature trees from selected species growing at the two drought experiment sites...
April 20, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28425026/photosynthetic-responses-to-temperature-across-leaf-canopy-ecosystem-scales-a-15-year-study-in-a-californian-oak-grass-savanna
#6
Siyan Ma, Jessica L Osuna, Joseph Verfaillie, Dennis D Baldocchi
Ecosystem CO2 fluxes measured with eddy-covariance techniques provide a new opportunity to retest functional responses of photosynthesis to abiotic factors at the ecosystem level, but examining the effects of one factor (e.g., temperature) on photosynthesis remains a challenge as other factors may confound under circumstances of natural experiments. In this study, we developed a data mining framework to analyze a set of ecosystem CO2 fluxes measured from three eddy-covariance towers, plus a suite of abiotic variables (e...
April 19, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28424726/size-mediated-interaction-between-a-cushion-species-and-other-non-cushion-species-at-high-elevations-of-the-hengduan-mountains-sw-china
#7
Yang Yang, Jian-Guo Chen, Christian Schöb, Hang Sun
Arenaria polytrichoides (Caryophyllaceae) is a common cushion plant occurring at high elevations in the Himalaya-Hengduan Mountains, SW China. It frequently has other non-cushion species growing within its canopy, forming a contrast with the surrounding areas because it creates patches of higher diversity and greater biomass. In this study, we examined the relationship between the cushions and associated non-cushion species along a gradient of cushion size. A total of 200 A. polytrichoides individuals were selected to fit four size classes...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28423342/a-broadly-neutralizing-antibody-targets-the-dynamic-hiv-envelope-trimer-apex-via-a-long-rigidified-and-anionic-%C3%AE-hairpin-structure
#8
Jeong Hyun Lee, Raiees Andrabi, Ching-Yao Su, Anila Yasmeen, Jean-Philippe Julien, Leopold Kong, Nicholas C Wu, Ryan McBride, Devin Sok, Matthias Pauthner, Christopher A Cottrell, Travis Nieusma, Claudia Blattner, James C Paulson, Per Johan Klasse, Ian A Wilson, Dennis R Burton, Andrew B Ward
Broadly neutralizing antibodies (bnAbs) to HIV delineate vaccine targets and are prophylactic and therapeutic agents. Some of the most potent bnAbs target a quaternary epitope at the apex of the surface HIV envelope (Env) trimer. Using cryo-electron microscopy, we solved the atomic structure of an apex bnAb, PGT145, in complex with Env. We showed that the long anionic HCDR3 of PGT145 penetrated between glycans at the trimer 3-fold axis, to contact peptide residues from all three Env protomers, and thus explains its highly trimer-specific nature...
April 18, 2017: Immunity
https://www.readbyqxmd.com/read/28421698/historical-harvests-reduce-neighboring-old-growth-basal-area-across-a-forest-landscape
#9
David M Bell, Thomas A Spies, Robert Pabst
While advances in remote sensing have made stand, landscape, and regional assessments of the direct impacts of disturbance on forests quite common, the edge influence of timber harvesting on the structure of neighboring unharvested forests has not been examined extensively. In this study, we examine the impact of historical timber harvests on basal area patterns of neighboring old-growth forests to assess the magnitude and scale of harvest edge influence in a forest landscape of western Oregon, USA. We used lidar data and forest plot measurements to construct 30-m resolution live tree basal area maps in lower and middle elevation mature and old-growth forests...
April 19, 2017: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/28419598/biological-traits-rather-than-environment-shape-detection-curves-of-large-vertebrates-in-neotropical-rainforests
#10
Thomas Denis, Cécile Richard-Hansen, Olivier Brunaux, Marie-Pierre Etienne, Stéphane Guitet, Bruno Hérault
Line transect surveys are widely used in neotropical rainforests to estimate the population abundance of medium- and large-sized vertebrates. The use of indices such as Encounter Rate has been criticized because the probability of animal detection may fluctuate due to the heterogeneity of environmental conditions among sites. In addition, the morphological and behavioral characteristics (biological traits) of species affect their detectability. In this study, we compared the extent to which environmental conditions and species' biological traits bias abundance estimates in terra firme rainforests in French Guiana...
April 17, 2017: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/28418158/the-phenology-of-leaf-quality-and-its-within-canopy-variation-are-essential-for-accurate-modeling-of-photosynthesis-in-tropical-evergreen-forests
#11
Jin Wu, Shawn P Serbin, Xiangtao Xu, Loren P Albert, Min Chen, Ran Meng, Scott R Saleska, Alistair Rogers
Leaf quantity (i.e. canopy leaf area index, LAI), quality (i.e. per-area photosynthetic capacity), and longevity all influence the photosynthetic seasonality of tropical evergreen forests. However, these components of tropical leaf phenology are poorly represented in most terrestrial biosphere models (TBMs). Here, we explored alternative options for the representation of leaf phenology effects in TBMs that employ the Farquahar, von Caemmerer & Berry (FvCB) representation of CO2 assimilation. We developed a two-fraction leaf (sun and shade), two-layer canopy (upper and lower) photosynthesis model to evaluate different modeling approaches and assessed three components of phenological variations (i...
April 18, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28417324/current-remote-sensing-approaches-to-monitoring-forest-degradation-in-support-of-countries-measurement-reporting-and-verification-mrv-systems-for-redd
#12
REVIEW
Anthea L Mitchell, Ake Rosenqvist, Brice Mora
Forest degradation is a global phenomenon and while being an important indicator and precursor to further forest loss, carbon emissions due to degradation should also be accounted for in national reporting within the frame of UN REDD+. At regional to country scales, methods have been progressively developed to detect and map forest degradation, with these based on multi-resolution optical, synthetic aperture radar (SAR) and/or LiDAR data. However, there is no one single method that can be applied to monitor forest degradation, largely due to the specific nature of the degradation type or process and the timeframe over which it is observed...
December 2017: Carbon Balance and Management
https://www.readbyqxmd.com/read/28413848/impact-of-data-model-and-point-density-on-aboveground-forest-biomass-estimation-from-airborne-lidar
#13
Mariano Garcia, Sassan Saatchi, Antonio Ferraz, Carlos Alberto Silva, Susan Ustin, Alexander Koltunov, Heiko Balzter
BACKGROUND: Accurate estimation of aboveground forest biomass (AGB) and its dynamics is of paramount importance in understanding the role of forest in the carbon cycle and the effective implementation of climate change mitigation policies. LiDAR is currently the most accurate technology for AGB estimation. LiDAR metrics can be derived from the 3D point cloud (echo-based) or from the canopy height model (CHM). Different sensors and survey configurations can affect the metrics derived from the LiDAR data...
December 2017: Carbon Balance and Management
https://www.readbyqxmd.com/read/28413232/the-freshwater-red-alga-batrachospermum-turfosum-florideophyceae-can-acclimate-to-a-wide-range-of-light-and-temperature-conditions
#14
Siegfried Aigner, Andreas Holzinger, Ulf Karsten, Ilse Kranner
Batrachospermum turfosum Bory is one of the generalists among the few red algae that have adapted to freshwater habitats, occurring in a variety of primarily shaded, nutrient-poor micro-habitats with lotic (running) or lentic (standing) waters. Seasonal variations in water level and canopy cover can expose this sessile alga to widely fluctuating temperatures, solar irradiation and nutrient availability. Here we report on the ecophysiology of B. turfosum collected from an ultra-oligotrophic bog pool in the Austrian Alps...
2017: Phycologia
https://www.readbyqxmd.com/read/28413231/development-of-a-roof-bolter-canopy-air-curtain-for-respirable-dust-control
#15
W R Reed, G J Joy, B Kendall, A Bailey, Y Zheng
Testing of the roof bolter canopy air curtain (CAC) designed by the U.S. National Institute for Occupational Safety and Health (NIOSH) has gone through many iterations, demonstrating successful dust control performance under controlled laboratory conditions. J.H. Fletcher & Co., an original equipment manufacturer of mining equipment, further developed the concept by incorporating it into the design of its roof bolting machines. In the present work, laboratory testing was conducted, showing dust control efficiencies ranging from 17...
January 2017: Mining Engineering
https://www.readbyqxmd.com/read/28407187/genetic-variability-and-expression-of-agro-morphological-traits-among-genotypes-of-coffea-arabica-being-promoted-by-supplementary-irrigation
#16
W N Rodrigues, S V B Brinate, L D Martins, T V Colodetti, M A Tomaz
The use of supplementary irrigation to sustain the plantation during moments of severe water stress or moments of high water demand is becoming almost a norm to keep sustainable crops, especially due to the climate changes and the high frequency in which climate extremes are occurring lately. The objective of this study was to evaluate the agronomic performance and expression of genetic variability among genotypes of Coffea arabica L. cultivated in farming systems with different levels of water supply, focusing on rainfed or supplementary irrigated systems...
April 13, 2017: Genetics and Molecular Research: GMR
https://www.readbyqxmd.com/read/28405287/the-impact-of-climate-change-on-the-distribution-of-two-threatened-dipterocarp-trees
#17
Jiban C Deb, Stuart Phinn, Nathalie Butt, Clive A McAlpine
Two ecologically and economically important, and threatened Dipterocarp trees Sal (Shorea robusta) and Garjan (Dipterocarpus turbinatus) form mono-specific canopies in dry deciduous, moist deciduous, evergreen, and semievergreen forests across South Asia and continental parts of Southeast Asia. They provide valuable timber and play an important role in the economy of many Asian countries. However, both Dipterocarp trees are threatened by continuing forest clearing, habitat alteration, and global climate change...
April 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28405214/a-real-time-phenotyping-framework-using-machine-learning-for-plant-stress-severity-rating-in-soybean
#18
Hsiang Sing Naik, Jiaoping Zhang, Alec Lofquist, Teshale Assefa, Soumik Sarkar, David Ackerman, Arti Singh, Asheesh K Singh, Baskar Ganapathysubramanian
BACKGROUND: Phenotyping is a critical component of plant research. Accurate and precise trait collection, when integrated with genetic tools, can greatly accelerate the rate of genetic gain in crop improvement. However, efficient and automatic phenotyping of traits across large populations is a challenge; which is further exacerbated by the necessity of sampling multiple environments and growing replicated trials. A promising approach is to leverage current advances in imaging technology, data analytics and machine learning to enable automated and fast phenotyping and subsequent decision support...
2017: Plant Methods
https://www.readbyqxmd.com/read/28402782/ecology-and-pathology-of-phytophthora-its-clade-3-species-in-forests-in-western-oregon-usa
#19
Everett M Hansen, Paul W Reeser, Wendy Sutton
Phytophthora species are widespread and diverse in forest ecosystems, but little is known about their ecology. We explore ecological attributes of the closely related clade 3 species that occur sympatrically in western North American forests. We address the population structure, pathology, and epidemiology of P. ilicis, P. nemorosa, P. pluvialis, P. pseudosyringae, and P. psychrophila. Phytophthora species were isolated from plant tissues, rainwater falling through the forest canopy, streams, and soils in forests in western Oregon...
2017: Mycologia
https://www.readbyqxmd.com/read/28399262/significant-contribution-from-foliage-derived-aba-in-regulating-gas-exchange-in-pinus-radiata
#20
Patrick J Mitchell, Scott A M McAdam, Elizabeth A Pinkard, Timothy J Brodribb
The complex regulatory system controlling stomata involves physical and chemical signals that affect guard cell turgor to bring about changes in stomatal conductance (gs). Abscisic acid (ABA) closes stomata, yet the mechanisms controlling foliar ABA status in tree species remain unclear. The importance of foliage-derived ABA in regulating gas exchange was evaluated under treatments that affected phloem export through girdling and reduced water availability in the tree species, Pinus radiata (D. Don). Branch- and whole-plant girdling increased foliar ABA levels leading to declines in gs, despite no change in plant water status...
February 1, 2017: Tree Physiology
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