<?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%">David, Teresa S.</style></author><author><style face="normal" font="default" size="100%">Pinto, Clara A.</style></author><author><style face="normal" font="default" size="100%">Nadezhdina, Nadezhda</style></author><author><style face="normal" font="default" size="100%">Kurz-Besson, Cathy</style></author><author><style face="normal" font="default" size="100%">Henriques, Manuel O.</style></author><author><style face="normal" font="default" size="100%">Quilhó, Teresa</style></author><author><style face="normal" font="default" size="100%">Čermák, Jan</style></author><author><style face="normal" font="default" size="100%">Chaves, M. Manuela</style></author><author><style face="normal" font="default" size="100%">Pereira, João S.</style></author><author><style face="normal" font="default" size="100%">David, Jorge S.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Root functioning, tree water use and hydraulic redistribution in Quercus suber trees: A modeling approach based on root sap flow</style></title><secondary-title><style face="normal" font="default" size="100%">Forest Ecology and Management</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Drought</style></keyword><keyword><style  face="normal" font="default" size="100%">groundwater</style></keyword><keyword><style  face="normal" font="default" size="100%">soil water</style></keyword><keyword><style  face="normal" font="default" size="100%">Stable isotopes</style></keyword><keyword><style  face="normal" font="default" size="100%">xylem anatomy</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/S0378112713004441</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">307</style></volume><pages><style face="normal" font="default" size="100%">136 - 146</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Mediterranean evergreen oaks have to survive a long summer drought. Roots may play a relevant role under these conditions. We studied their structure and function in a mature Quercus suber L. tree in central Portugal. The root system was mapped till the lowest water table level (4.5 m depth). Xylem anatomy was analyzed in a vertical profile belowground. Sap flow was continuously monitored for 1.5 yrs in the stem and roots of this intensively studied tree (heat field deformation method) and in the stem of four trees (Granier method), in relation to environmental variables and predawn leaf water potential. The sources of water uptake were assessed by stable isotope analyses in summer. Results showed a dimorphic root system with a network of superficial roots linked to sinker roots, and a taproot diverting into tangles of deep fine roots submerged for long periods, with parenchyma aerenchyma. Transpiration was not restricted in summer due to root access to groundwater. The isotopic δ18O signature of twig xylem water was similar to that of groundwater in the dry season. Two functional types of superficial roots were identified: shallow connected and deep connected roots. A modeling approach was built considering that each superficial root was linked to a sinker, with part of the root deep connected (between the stem and the sinker) and part shallow connected (between the sinker and topsoil). This conceptual framework simulated tree stem sap flow from root sap flow with a high efficiency (R2 = 0.85) in four plot trees. On an annual basis, soil water and groundwater contributions were 69.5% and 30.5% of stem flow, respectively. Annual hydraulic lift and hydraulic descent were 0.9% and 37.0% of stem flow, respectively. The trees maximize the exploitation of the environmental resources by using the topsoil water during most of the year, and groundwater together with hydraulic lift (nutrient supply) in the dry summer. This study shows that a dimorphic root system, with roots reaching groundwater, is an efficient strategy of Q. suber trees to cope with seasonal drought. Knowledge of the functional behavior of Q. suber trees under shallow water table conditions may contribute to the definition of better adapted management practices and to anticipate their responses to climate change.</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%">David, T. S.</style></author><author><style face="normal" font="default" size="100%">Henriques, M. O.</style></author><author><style face="normal" font="default" size="100%">Kurz-Besson, C.</style></author><author><style face="normal" font="default" size="100%">Nunes, J.</style></author><author><style face="normal" font="default" size="100%">Valente, F.</style></author><author><style face="normal" font="default" size="100%">Vaz, M.</style></author><author><style face="normal" font="default" size="100%">Pereira, J. S.</style></author><author><style face="normal" font="default" size="100%">Siegwolf, R.</style></author><author><style face="normal" font="default" size="100%">Chaves, M. M.</style></author><author><style face="normal" font="default" size="100%">Gazarini, L. C.</style></author><author><style face="normal" font="default" size="100%">David, J. S.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Water-use strategies in two co-occurring Mediterranean evergreen oaks: surviving the summer drought</style></title><secondary-title><style face="normal" font="default" size="100%">Tree Physiology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">canopy conductance</style></keyword><keyword><style  face="normal" font="default" size="100%">groundwater</style></keyword><keyword><style  face="normal" font="default" size="100%">Hydraulic conductance</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf water potential</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber</style></keyword><keyword><style  face="normal" font="default" size="100%">sap flow</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2007///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://treephys.oxfordjournals.org/content/27/6/793.abstract</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">27</style></volume><pages><style face="normal" font="default" size="100%">793 - 803</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In the Mediterranean evergreen oak woodlands of southern Portugal, the main tree species are Quercus ilex ssp. rotundifolia Lam. (holm oak) and Quercus suber L. (cork oak). We studied a savannah-type woodland where these species coexist, with the aim of better understanding the mechanisms of tree adaptation to seasonal drought. In both species, seasonal variations in transpiration and predawn leaf water potential showed a maximum in spring followed by a decline through the rainless summer and a recovery with autumn rainfall. Although the observed decrease in predawn leaf water potential in summer indicates soil water depletion, trees maintained transpiration rates above 0.7 mm day−1 during the summer drought. By that time, more than 70% of the transpired water was being taken from groundwater sources. The daily fluctuations in soil water content suggest that some root uptake of groundwater was mediated through the upper soil layers by hydraulic lift. During the dry season, Q. ilex maintained higher predawn leaf water potentials, canopy conductances and transpiration rates than Q. suber. The higher water status of Q. ilex was likely associated with their deeper root systems compared with Q. suber. Whole-tree hydraulic conductance and minimum midday leaf water potential were lower in Q. ilex, indicating that Q. ilex was more tolerant to drought than Q. suber. Overall, Q. ilex seemed to have more effective drought avoidance and drought tolerance mechanisms than Q. suber.</style></abstract><issue><style face="normal" font="default" size="100%">6</style></issue><notes><style face="normal" font="default" size="100%">10.1093/treephys/27.6.79310.1093/treephys/27.6.793</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>7</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Dijck, Simone J E Van</style></author><author><style face="normal" font="default" size="100%">Laouina, Abdellah</style></author><author><style face="normal" font="default" size="100%">Carvalho, Anabela V</style></author><author><style face="normal" font="default" size="100%">Antari, Mostafa</style></author><author><style face="normal" font="default" size="100%">Rocha, Alfredo</style></author><author><style face="normal" font="default" size="100%">Borrego, Carlos</style></author><author><style face="normal" font="default" size="100%">Coen, J</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">DESERTIFICATION IN NORTHERN MOROCCO DUE TO EFFECTS OF CLIMATE CHANGE ON GROUNDWATER RECHARGE</style></title><secondary-title><style face="normal" font="default" size="100%">Desertification in the Mediterranean Region a Security Issue</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">climate change</style></keyword><keyword><style  face="normal" font="default" size="100%">Grazing</style></keyword><keyword><style  face="normal" font="default" size="100%">groundwater</style></keyword><keyword><style  face="normal" font="default" size="100%">land degradation (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">Morocco</style></keyword><keyword><style  face="normal" font="default" size="100%">Precipitation</style></keyword><keyword><style  face="normal" font="default" size="100%">surface runoff</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year></dates><pages><style face="normal" font="default" size="100%">549-577</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Groundwater resources in Morocco are expected to shrink in the next decades due to an increasing withdrawal for rural and urban development, and a decreasing internal recharge by precipitation under the influence of climate change. The objective of this work is to analyse the recharge of groundwater systems in a region with traditional agriculture and current transformations in northern Morocco (Sehoul region) in response to future climate change and land degradation. Models were used to simulate climate change and effects on surface runoff and groundwater recharge. The climate models indicated increases in temperature and decreases in precipitation in all seasons in 2050 compared to 1990, and an increasing variability of autumn precipitation. Because most cultivated fields are freshly ploughed and sown in autumn, this will increase the risk of desertification due to declining groundwater recharge and increased surface runoff and erosion. This is confirmed by the results of the event-based surface runoff simulation for the 2050 climate. Surface runoff is mainly produced in ancient grazing fields and fallow fields. In view of the current transformation of collective grazing fields into cultivated land, problems with loss of rainfall in surface runoff and soil erosion could be mitigated by 1. early tillage of cultivated fields along the slope contour, followed by leveling, 2. locating cultivated fields downslope of grazing fields to enable the capturing of diffuse surface runoff coming from the grazing fields, and 3. leaving fallow fields untilled and covered with crop remnants. The groundwater modeling results indicate a decrease of the annual groundwater recharge by rainfall of 40-68% from the climate centered in 1990 to the climate centered in 2050. As a result, groundwater levels are predicted to fall up till 2005, but the results are unreliable due to model errors. However, the decreases in precipitation, infiltration and groundwater recharge predicted in this study may be expected to add to the observed trend of groundwater level decrease in the study area, and to continuing desertification.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>5</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Dijck, Simone J. E. Van</style></author><author><style face="normal" font="default" size="100%">Laouina, Abdellah</style></author><author><style face="normal" font="default" size="100%">Carvalho, Anabela V.</style></author><author><style face="normal" font="default" size="100%">Antari, Mostafa</style></author><author><style face="normal" font="default" size="100%">Rocha, Alfredo</style></author><author><style face="normal" font="default" size="100%">Borrego, Carlos</style></author><author><style face="normal" font="default" size="100%">Coen, J.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">DESERTIFICATION IN NORTHERN MOROCCO DUE TO EFFECTS OF CLIMATE CHANGE ON GROUNDWATER RECHARGE</style></title><secondary-title><style face="normal" font="default" size="100%">Desertification in the Mediterranean Region a Security Issue</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">climate change</style></keyword><keyword><style  face="normal" font="default" size="100%">Grazing</style></keyword><keyword><style  face="normal" font="default" size="100%">groundwater</style></keyword><keyword><style  face="normal" font="default" size="100%">land degradation (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">Morocco</style></keyword><keyword><style  face="normal" font="default" size="100%">Precipitation</style></keyword><keyword><style  face="normal" font="default" size="100%">surface runoff</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2006///</style></date></pub-dates></dates><pages><style face="normal" font="default" size="100%">549 - 577</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Groundwater resources in Morocco are expected to shrink in the next decades due to an increasing withdrawal for rural and urban development, and a decreasing internal recharge by precipitation under the influence of climate change. The objective of this work is to analyse the recharge of groundwater systems in a region with traditional agriculture and current transformations in northern Morocco (Sehoul region) in response to future climate change and land degradation. Models were used to simulate climate change and effects on surface runoff and groundwater recharge. The climate models indicated increases in temperature and decreases in precipitation in all seasons in 2050 compared to 1990, and an increasing variability of autumn precipitation. Because most cultivated fields are freshly ploughed and sown in autumn, this will increase the risk of desertification due to declining groundwater recharge and increased surface runoff and erosion. This is confirmed by the results of the event-based surface runoff simulation for the 2050 climate. Surface runoff is mainly produced in ancient grazing fields and fallow fields. In view of the current transformation of collective grazing fields into cultivated land, problems with loss of rainfall in surface runoff and soil erosion could be mitigated by 1. early tillage of cultivated fields along the slope contour, followed by leveling, 2. locating cultivated fields downslope of grazing fields to enable the capturing of diffuse surface runoff coming from the grazing fields, and 3. leaving fallow fields untilled and covered with crop remnants. The groundwater modeling results indicate a decrease of the annual groundwater recharge by rainfall of 40-68% from the climate centered in 1990 to the climate centered in 2050. As a result, groundwater levels are predicted to fall up till 2005, but the results are unreliable due to model errors. However, the decreases in precipitation, infiltration and groundwater recharge predicted in this study may be expected to add to the observed trend of groundwater level decrease in the study area, and to continuing desertification.</style></abstract><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;periodical: Desertification in the Mediterranean Region a Security Issue</style></notes></record></records></xml>