<?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><authors><author><style face="normal" font="default" size="100%">Wingate, Lisa</style></author><author><style face="normal" font="default" size="100%">SEIBT, ULLI</style></author><author><style face="normal" font="default" size="100%">MASEYK, KADMIEL</style></author><author><style face="normal" font="default" size="100%">OGÉE, JÉRÔME</style></author><author><style face="normal" font="default" size="100%">Almeida, Pedro</style></author><author><style face="normal" font="default" size="100%">YAKIR, D A N</style></author><author><style face="normal" font="default" size="100%">Pereira, João S</style></author><author><style face="normal" font="default" size="100%">MENCUCCINI, MAURIZIO</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Evaporation and carbonic anhydrase activity recorded in oxygen isotope signatures of net CO2 fluxes from a Mediterranean soil</style></title><secondary-title><style face="normal" font="default" size="100%">Global Change Biology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">atmospheric invasion</style></keyword><keyword><style  face="normal" font="default" size="100%">carbonic anhydrase</style></keyword><keyword><style  face="normal" font="default" size="100%">Drought</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean forests</style></keyword><keyword><style  face="normal" font="default" size="100%">oxygen isotopes</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil CO2 efflux</style></keyword><keyword><style  face="normal" font="default" size="100%">soil evaporation</style></keyword><keyword><style  face="normal" font="default" size="100%">soil water δ18O composition</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><publisher><style face="normal" font="default" size="100%">Blackwell Publishing Ltd</style></publisher><volume><style face="normal" font="default" size="100%">14</style></volume><pages><style face="normal" font="default" size="100%">2178-2193</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The oxygen stable isotope composition (δ18O) of CO2 is a valuable tool for studying the gas exchange between terrestrial ecosystems and the atmosphere. In the soil, it records the isotopic signal of water pools subjected to precipitation and evaporation events. The δ18O of the surface soil net CO2 flux is dominated by the physical processes of diffusion of CO2 into and out of the soil and the chemical reactions during CO2–H2O equilibration. Catalytic reactions by the enzyme carbonic anhydrase, reducing CO2 hydration times, have been proposed recently to explain field observations of the δ18O signatures of net soil CO2 fluxes. How important these catalytic reactions are for accurately predicting large-scale biosphere fluxes and partitioning net ecosystem fluxes is currently uncertain because of the lack of field data. In this study, we determined the δ18O signatures of net soil CO2 fluxes from soil chamber measurements in a Mediterranean forest. Over the 3 days of measurements, the observed δ18O signatures of net soil CO2 fluxes became progressively enriched with a well-characterized diurnal cycle. Model simulations indicated that the δ18O signatures recorded the interplay of two effects: (1) progressive enrichment of water in the upper soil by evaporation, and (2) catalytic acceleration of the isotopic exchange between CO2 and soil water, amplifying the contributions of ‘atmospheric invasion’ to net signatures. We conclude that there is a need for better understanding of the role of enzymatic reactions, and hence soil biology, in determining the contributions of soil fluxes to oxygen isotope signals in atmospheric CO2.</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%">Merouani, Hachemi</style></author><author><style face="normal" font="default" size="100%">Branco, Carmen</style></author><author><style face="normal" font="default" size="100%">Almeida, Maria Helena</style></author><author><style face="normal" font="default" size="100%">Pereira, João S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Comportement physiologique des glands de chêne liège (Quercus suber L.) durant leur conservation et variabilité inter-individus producteurs</style></title><secondary-title><style face="normal" font="default" size="100%">Ann. For. Sci.</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">electrolyte leakage</style></keyword><keyword><style  face="normal" font="default" size="100%">germination</style></keyword><keyword><style  face="normal" font="default" size="100%">Moisture content</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">seed</style></keyword><keyword><style  face="normal" font="default" size="100%">storage</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><volume><style face="normal" font="default" size="100%">58</style></volume><pages><style face="normal" font="default" size="100%">143-153</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The mature acorns were harvested on twelve selected trees from a cork oak population in Southern Portugal (Herdade da Palma). After drying, the seed lots were stored on three types bags (polyethylene with 30 mm and 50 mm thick and plastic mesh), for six months at 0 oC. At the time of natural dissemination, the acorns from the majority of the trees from the same population were under the same state of morphological and physiological maturity. The moisture content was about 44-47% and a germination rate above 92% . At this time, the germination was very slow because of the existent embryonic dormancy that seems to be dependent on the individual trees. During the storage, germination rate is improved. This might be explained by the breaking dormancy during storage. The mean germination time was on an average 10 days for fresh seeds and decreased to about 4 days after 6 months storage. A relationship between viability and seed moisture content was observed. The Mean Germination Time of dried seed and stored seed for 4 months in plastic mesh bag increased to about 13 days. The germination capacity was strongly decreased when the seed moisture content was below 30%</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%">Merouani, Hachemi</style></author><author><style face="normal" font="default" size="100%">Branco, Carmen</style></author><author><style face="normal" font="default" size="100%">Almeida, Maria Helena</style></author><author><style face="normal" font="default" size="100%">Pereira, João S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effects of acorn storage duration and parental tree on emergence and physiological status of Cork oak (Quercus suber L.) seedlings</style></title><secondary-title><style face="normal" font="default" size="100%">Ann. For. Sci.</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">root radio</style></keyword><keyword><style  face="normal" font="default" size="100%">Seed size</style></keyword><keyword><style  face="normal" font="default" size="100%">seed storage</style></keyword><keyword><style  face="normal" font="default" size="100%">seedling growth</style></keyword><keyword><style  face="normal" font="default" size="100%">shoot</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year></dates><volume><style face="normal" font="default" size="100%">58</style></volume><pages><style face="normal" font="default" size="100%">543-554</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">This study was conducted to evaluate how parental trees and seed storage duration influenced subsequent seedling physiological status and growth. Seedling emergence rate was higher than 90% independently of the duration of seed storage or parental trees. Seed storage shortened significantly the time and increased the uniformity of seedling emergence. Consequently, the delayed seedling emergence from fresh seeds could be explained by epicotyl dormancy. Seed size varied with parental tree. Seedling growth rate was greatly affected by seed size, independently of storage treatment. Seedlings originating from large seeds (&gt; 5 g) had the fastest growth rates and seedlings from the smallest seeds (&lt; 4 g) had the slowest. Final shoot height, however, depended on the duration of seed storage. The seed size and the duration of storage had a great effect on the initial rate of leaf production, but did not affect the final number of leaves. Leaf chlorophyll concentration was reduced as the duration of seed storage increased but was independent of parental tree (i.e., seed size). Seedling biomass was positively related to seed size. The duration of seed storage reduced the shoot/root ratio, but no significant effect was observed among parental trees. The shoot/root value of seedlings from stored seed was about 1.5 and the one of seedlings from fresh seed was about 2.</style></abstract></record></records></xml>