<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors></contributors><titles><title><style face="normal" font="default" size="100%">Acta Oecologica In fl uence of tree cover on herbaceous layer development and carbon and water fl uxes in a Portuguese cork-oak woodland</style></title><secondary-title><style face="normal" font="default" size="100%">Acta Oecologica</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2014</style></year></dates><publisher><style face="normal" font="default" size="100%">Elsevier Masson SAS</style></publisher><volume><style face="normal" font="default" size="100%">59</style></volume><pages><style face="normal" font="default" size="100%">35-45</style></pages><language><style face="normal" font="default" size="100%">eng</style></language></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors></contributors><titles><title><style face="normal" font="default" size="100%">Influence of tree cover on herbaceous layer development and carbon and water fluxes in a Portuguese cork-oak woodland</style></title><secondary-title><style face="normal" font="default" size="100%">Acta Oecologica</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2014</style></year></dates><volume><style face="normal" font="default" size="100%">59</style></volume><pages><style face="normal" font="default" size="100%">35-45</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Facilitation and competition between different vegetation layers may have a large impact on small-scale vegetation development. We propose that this should not only influence overall herbaceous layer yield but also species distribution and understory longevity, and hence the ecosystems carbon uptake capacity especially during spring. We analyzed the effects of trees on microclimate and soil properties (water and nitrate content) as well as the development of an herbaceous community layer regarding species composition, aboveground biomass and net water and carbon fluxes in a cork-oak woodland in Portugal, between April and November 2011. The presence of trees caused a significant reduction in photosynthetic active radiation of 35molm−2d−1 and in soil temperature of 5°C from April to October. At the same time differences in species composition between experimental plots located in open areas and directly below trees could be observed: species composition and abundance of functional groups became increasingly different between locations from mid April onwards. During late spring drought adapted native forbs had significantly higher cover and biomass in the open area while cover and biomass of grasses and nitrogen fixing forbs was highest under the trees. Further, evapotranspiration and net carbon exchange decreased significantly stronger under the tree crowns compared to the open during late spring and the die back of herbaceous plants occurred earlier and faster under trees. This was most likely caused by interspecific competition for water between trees and herbaceous plants, despite the more favorable microclimate conditions under the trees during the onset of summer drought.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Dubbert, Maren</style></author><author><style face="normal" font="default" size="100%">Cuntz, Matthias</style></author><author><style face="normal" font="default" size="100%">Piayda, Arndt</style></author><author><style face="normal" font="default" size="100%">Máguas, Cristina</style></author><author><style face="normal" font="default" size="100%">Werner, Christiane</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Partitioning evapotranspiration – Testing the Craig and Gordon model with field measurements of oxygen isotope ratios of evaporative fluxes</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Hydrology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Craig and Gordon</style></keyword><keyword><style  face="normal" font="default" size="100%">evaporation</style></keyword><keyword><style  face="normal" font="default" size="100%">Evapotranspiration</style></keyword><keyword><style  face="normal" font="default" size="100%">Kinetic fractionation</style></keyword><keyword><style  face="normal" font="default" size="100%">Laser spectroscopy</style></keyword><keyword><style  face="normal" font="default" size="100%">Stable oxygen isotopes</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2013</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2013///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0022169413004083</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">496</style></volume><pages><style face="normal" font="default" size="100%">142 - 153</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">su mmary Stable oxygen isotopes of water provide a valuable tracer for water movements within ecosystems and are used to estimate the contribution of transpiration to total ecosystem evapotranspiration (ft). We tested the Craig and Gordon equation against continuous field measurements of isotopic composition of evaporation and assessed the impact for partitioning evapotranspiration. Therefore, evaporation (E) and its isotopic signature (d18OE) on bare soil plots, as well as evapotranspiration (ET) and its correspond- ing isotopic composition of (d18OET) of an herbaceous layer was measured with a cavity ring-down spec- trometer connected to a soil chamber on a field site in central Portugal. We quantified the variation in d18OE arising from uncertainties in the determination of environmental input variables to the Craig and Gordon equation: the isotope signature (d18Oe) and the temperature at the evaporating site (Te), and the kinetic fractionation factor (ak). We could hence quantify ft based on measured d18OET, modeled d18OE from observed soil water isotopic composition at the evaporating site (d18Oe), and modeled d18O of transpiration (d18OT) from observed total soil water isotopic composition. Our results demonstrate that predicting d18OE using the Craig and Gordon equation leads to good agree- ment with measured d18OE given that the temperature and 18O isotope profiles of the soil are thoroughly characterized. However, modeled d18OE is highly sensitive to changes in Te and d18Oe as well as ak. This markedly affected the partition results of transpiration and evaporation from the total ET flux: The frac- tion of transpiration (ft) varied strongly using different formulations for ak and assuming steady or non- steady state transpiration. These findings provide a first comparison of laser-based and modeled isotopic compositions of evaporation based on the Craig and Gordon equation under field conditions. This is of special interest for studies using stable isotopes to separate soil evaporation and plant transpiration fluxes and highlights the need for a thorough characterization of the micrometeorological and isotopic constitution of the upper soil layer to locate the evaporating front with a resolution of a few cm soil depths. We also call on a better characterization of the kinetic fractionation factor of soil evaporation.</style></abstract></record></records></xml>