Pahissa J., Catalan J., Morabito G., Dorflinger G., Ferreira J., Laplace-Treyture C., Girbea R., Marchetto A., Polykarpou P., de Hoyos C. (2015) Benefits and limitations of an intercalibration of phytoplankton assessment methods based on the Mediterranean GIG reservoir experience. Science of the Total Environment. 538: 169-179.EnllaçDoi: 10.1016/j.scitotenv.2015.08.042
The status of European legislation regarding inland water quality after the enactment of the Water Framework Directive (WFD) originated scientific effort to develop reliable methods, primarily based on biological parameters. An important aspect of the process was to ensure that quality assessment was comparable between the different Member States. The Intercalibration process (IC), required in the WFD ensures the unbiased application of the norm. The presented results were developed in the context of the 2nd IC phase. An overview of the reservoir type definition of the Lake Mediterranean Geographical Intercalibration Group, where four types were considered divided by both alkalinity and climate, together with the results for selection of Maximum Ecological Potential sites (MEP) are presented. MEP reservoirs were selected based on pressure and biological variables. Three phytoplankton-based assessment methods were intercalibrated using data from Mediterranean countries. The Mediterranean Assessment System for Reservoirs Phytoplankton (Spain), the New Mediterranean Assessment System for Reservoirs Phytoplankton (Portugal and Cyprus) and the New Italian Method (Italy) were applied. These three methods were compared through option 3 of the Intercalibration Guide. The similarity of the assessments was quantified, and the Good/Moderate (GM) boundaries assessed. All three methods stood as comparable at the GM boundary except for the MASRP in siliceous wet reservoirs, which was slightly stricter. Finally, the main taxonomic groups represented in the phytoplankton community at MEP conditions were identified, as well as their main changes with an increasing trophic status. MEP sites are dominated by chrysophytes in siliceous wet reservoirs and by the diatoms Cyclotella and Achnanthes in calcareous ones. Cyanobacteria take over the community in both calcareous and siliceous wet reservoirs as eutrophication increases. In summary, the relevance and reliability of the quality assessment methods compared were confirmed both from an ecological perspective and a health risk management point of view. © 2015 Elsevier B.V.
Palmer J.R.B., Pytlikova M. (2015) Labor market laws and intra-European migration: The role of the state in shaping destination choices. European Journal of Population. 31: 127-153.EnllaçDoi: 10.1007/s10680-015-9341-5
This article investigates the relationship between migrants’ destination choices and the formal labor market access afforded by multiple potential host countries in the context of the EU’s eastward enlargement. We use an index of labor market access laws combined with data on migration from new EU member states into the existing states of the EU and EFTA from 2004 through 2010 to test whether (1) migrants are attracted to destinations that give them greater formal labor market access, (2) migration flows to any given destination are influenced by the labor market policies of competing destinations, and (3) the influence of labor market laws on migrant flows is mediated by social networks, language ability, and educational level. Our data support the first two propositions and partly support the third: Migration between origin/destination pairs was positively associated with the loosening of destination labor market restrictions, while negatively associated with the loosening of competing destinations’ labor market restrictions. In addition, the influence of destination labor market access appears to be weaker for destinations in which migrants have larger existing co-national networks, and for migrants from countries with languages that are more similar to the destination language, although we do not discern a clear mediating effect of education level. Our models also include variables for a set of economic indicators, social welfare spending, geographic distance, and historical relationships, and the estimated coefficients on these variables are largely in line with theoretical predictions. By combining rich EU data with a unique approach to evaluating competing legal regimes, the analysis helps us better understand how law shapes migration in a multi-destination world. © 2015, Springer Science+Business Media Dordrecht.
Pascual D., Pla E., Lopez-Bustins J.A., Retana J., Terradas J. (2015) Impacts of climate change on water resources in the Mediterranean Basin: a case study in Catalonia, Spain [Impacts du changement climatique sur les ressources en eau dans le bassin méditerranéen : une étude de cas en Catalogne, Espagne]. Hydrological Sciences Journal. : 0-0.EnllaçDoi: 10.1080/02626667.2014.947290
Most climate change projections show important decreases in water availability in the Mediterranean region by the end of this century. We assess those main climate change impacts on water resources in three medium-sized catchments with varying climatic conditions in northeastern Spain. A combination of hydrological modelling and climate projections with B1 and A2 IPCC emission scenarios is performed to infer future streamflows. The largest reduction (34%) in mean streamflows (for 2076–2100) is expected in the headwaters of the two wettest catchments, while lower decreases (25% of mean value for 2076–2100) are expected in the drier one. In all three catchments, autumn and summer are the seasons with the most notable projected decreases in streamflow, of 50% and 30%, respectively. Thus, ecological flows in the study area might be noticeably influenced by climate change, especially in the headwaters of the wet catchments.Editor Z.W. Kundzewicz © 2015 IAHS
Penuelas J., Bartrons M., Llusia J., Filella I. (2015) Sensing the energetic status of plants and ecosystems. Trends in Plant Science. 20: 528-530.EnllaçDoi: 10.1016/j.tplants.2015.07.002
The emerging consistency of the relationship between biochemical, optical, and odorous signals emitted by plants and ecosystems offers promising prospects for continuous local and global monitoring of the energetic status of plants and ecosystems, and therefore of their processing of energy and matter. © 2015 Elsevier Ltd.
Pfautsch S., Holtta T., Mencuccini M. (2015) Hydraulic functioning of tree stems - Fusing ray anatomy, radial transfer and capacitance. Tree Physiology. 35: 706-722.EnllaçDoi: 10.1093/treephys/tpv058
Not long ago, textbooks on plant physiology divulged the view that phloem and xylem are separate transport systems with exclusive functions. Phloem was flowing downwards providing roots with carbohydrates. Xylem transported water upwards from roots to leaves. This simplified view has changed forever. Today we have a much-refined understanding of the complex transport mechanisms, regulatory functions and surprisingly ingenuous solutions trees have evolved to distribute carbohydrates and water internally to fuel growth and help mediate biotic and abiotic stresses. This review focuses on functional links between tissues of the inner bark region (i.e., more than just phloem) and the xylem, facilitated by radially aligned and interconnected parenchyma cells, called rays. Rays are usually found along the entire vertical axis of tree stems, mediating a number of transport processes. We use a top-down approach to unveil the role of rays in these processes. Due to the central role of rays in facilitating the coupling of inner bark and xylem we dedicate the first section to ray anatomy, pathways and control mechanisms involved in radial transport. In the second section, basic concepts and models for radial movement through rays are introduced and their impacts on water and carbon fluxes at the whole-tree level are discussed. This section is followed by a closer look at the capacitive function of composite tissues in stems where gradual changes in water potential generate a diurnal 'pulse'. We explain how this pulse can be measured and interpreted, and where the limitations of such analyses are. Towards the end of this review, we include a brief description of the role of radial transport during limited availability of water. By elucidating the strong hydraulic link between inner bark and xylem, the traditional view of two separate transport systems dissolves and the idea of one interconnected, yet highly segregated transport network for carbohydrates and water arises. © 2015 The Author 2015. Published by Oxford University Press. All rights reserved.
Piao S., Tan J., Chen A., Fu Y.H., Ciais P., Liu Q., Janssens I.A., Vicca S., Zeng Z., Jeong S.-J., Li Y., Myneni R.B., Peng S., Shen M., Penuelas J. (2015) Leaf onset in the northern hemisphere triggered by daytime temperature. Nature Communications. 6: 0-0.EnllaçDoi: 10.1038/ncomms7911
Recent warming significantly advanced leaf onset in the northern hemisphere. This signal cannot be accurately reproduced by current models parameterized by daily mean temperature (Tmean). Here using in situ observations of leaf unfolding dates (LUDs) in Europe and the United States, we show that the interannual anomalies of LUD during 1982-2011 are triggered by daytime (Tmax) more than by nighttime temperature (Tmin). Furthermore, an increase of 1°C in Tmax would advance LUD by 4.7 days in Europe and 4.3 days in the United States, more than the conventional temperature sensitivity estimated from Tmean. The triggering role of Tmax, rather than the Tmin or Tmean variable, is also supported by analysis of the large-scale patterns of satellite-derived vegetation green-up in spring in the northern hemisphere (>30°N). Our results suggest a new conceptual framework of leaf onset using daytime temperature to improve the performance of phenology modules in current Earth system models. © 2015 Macmillan Publishers Limited. All rights reserved.
Pinol J., Mir G., Gomez-Polo P., Agusti N. (2015) Universal and blocking primer mismatches limit the use of high-throughput DNA sequencing for the quantitative metabarcoding of arthropods. Molecular Ecology Resources. : 0-0.EnllaçDoi: 10.1111/1755-0998.12355
The quantification of the biological diversity in environmental samples using high-throughput DNA sequencing is hindered by the PCR bias caused by variable primer-template mismatches of the individual species. In some dietary studies, there is the added problem that samples are enriched with predator DNA, so often a predator-specific blocking oligonucleotide is used to alleviate the problem. However, specific blocking oligonucleotides could coblock nontarget species to some degree. Here, we accurately estimate the extent of the PCR biases induced by universal and blocking primers on a mock community prepared with DNA of twelve species of terrestrial arthropods. We also compare universal and blocking primer biases with those induced by variable annealing temperature and number of PCR cycles. The results show that reads of all species were recovered after PCR enrichment at our control conditions (no blocking oligonucleotide, 45 °C annealing temperature and 40 cycles) and high-throughput sequencing. They also show that the four factors considered biased the final proportions of the species to some degree. Among these factors, the number of primer-template mismatches of each species had a disproportionate effect (up to five orders of magnitude) on the amplification efficiency. In particular, the number of primer-template mismatches explained most of the variation (~3/4) in the amplification efficiency of the species. The effect of blocking oligonucleotide concentration on nontarget species relative abundance was also significant, but less important (below one order of magnitude). Considering the results reported here, the quantitative potential of the technique is limited, and only qualitative results (the species list) are reliable, at least when targeting the barcoding COI region. © 2014 John Wiley & Sons Ltd.
Preece C., Livarda A., Wallace M., Martin G., Charles M., Christin P.-A., Jones G., Rees M., Osborne C.P. (2015) Were Fertile Crescent crop progenitors higher yielding than other wild species that were never domesticated?. New Phytologist. : 0-0.EnllaçDoi: 10.1111/nph.13353
Summary: During the origin of agriculture in the Fertile Crescent, the broad spectrum of wild plant species exploited by hunter-gatherers narrowed dramatically. The mechanisms responsible for this specialization and the associated domestication of plants are intensely debated. We investigated why some species were domesticated rather than others, and which traits they shared. We tested whether the progenitors of cereal and pulse crops, grown individually, produced a higher yield and less chaff than other wild grasses and legumes, thereby maximizing the return per seed planted and minimizing processing time. We compared harvest traits of species originating from the Fertile Crescent, including those for which there is archaeological evidence of deliberate collection. Unexpectedly, wild crop progenitors in both families had neither higher grain yield nor, in grasses, less chaff, although they did have larger seeds. Moreover, small-seeded grasses actually returned a higher yield relative to the mass of seeds sown. However, cereal progenitors had threefold fewer seeds per plant, representing a major difference in how seeds are packaged on plants. These data suggest that there was no intrinsic yield advantage to adopting large-seeded progenitor species as crops. Explaining why Neolithic agriculture was founded on these species, therefore, remains an important unresolved challenge. © 2015 New Phytologist Trust.
Pérez Hidalgo N., Hernández-Castellano C., Garcia Figueres F. (2015) First record of neophyllaphis podocarpi Takahashi (Hemiptera: Aphididae) in the Iberian Peninsula. EPPO Bulletin. 45: 103-105.EnllaçDoi: 10.1111/epp.12177
Quentin A.G., Pinkard E.A., Ryan M.G., Tissue D.T., Baggett L.S., Adams H.D., Maillard P., Marchand J., Landhäusser S.M., Lacointe A., Gibon Y., Anderegg W.R.L., Asao S., Atkin O.K., Bonhomme M., Claye C., Chow P.S., Clément-Vidal A., Davies N.W., Dickman L.T., Dumbur R., Ellsworth D.S., Falk K., Galiano L., Grünzweig J.M., Hartmann H., Hoch G., Hood S., Jones J.E., Koike T., Kuhlmann I., Lloret F., Maestro M., Mansfield S.D., Martínez-Vilalta J., Maucourt M., McDowell N.G., Moing A., Muller B., Nebauer S.G., Niinemets U., Palacio S., Piper F., Raveh E., Richter A., Rolland G., Rosas T., Joanis B.S., Sala A., Smith R.A., Sterck F., Stinziano J.R., Tobias M., Unda F., Watanabe M., Way D.A., Weerasinghe L.K., Wild B., Wiley E., Woodruff D.R. (2015) Non-structural carbohydrates in woody plants compared among laboratories. Tree Physiology. 35: 1146-1165.EnllaçDoi: 10.1093/treephys/tpv073
Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g-1 for soluble sugars, 6-533 (mean = 94) mg g-1 for starch and 53-649 (mean = 153) mg g-1 for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R2 = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g-1 for total NSC, compared with the range of laboratory estimates of 596 mg g-1. Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory may be comparable within and between laboratories, especially for starch. To obtain comparable NSC estimates, we suggest that users can either adopt the reference method given in this publication, or report estimates for a portion of samples using the reference method, and report estimates for a standard reference material. Researchers interested in NSC estimates should work to identify and adopt standard methods. © The Author 2015.
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