<?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%">Cubera, Elena</style></author><author><style face="normal" font="default" size="100%">Moreno, Gerardo</style></author><author><style face="normal" font="default" size="100%">Solla, Alejandro</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Quercus ilex root growth in response to heterogeneous conditions of soil bulk density and soil NH4-N content</style></title><secondary-title><style face="normal" font="default" size="100%">Soil and Tillage Research</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Oak decline</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Root density</style></keyword><keyword><style  face="normal" font="default" size="100%">Root depth</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil bulk density</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil NH4 content</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2009///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://linkinghub.elsevier.com/retrieve/pii/S0167198708001724</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">103</style></volume><pages><style face="normal" font="default" size="100%">16 - 22</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">A greenhouse study examined the effects of heterogeneous conditions of soil bulk density and soil NH4-N content on the growth of holm oak (Quercus ilex L.) seedlings over an 8-month period. Heterogeneity of soil was produced inside 150 cm depth pots, by applying manual compaction or enriching different soil layers with NH4 (vertical heterogeneity) and, by splitting the root system into two columns with differing soil bulk density or NH4 conditions (horizontal heterogeneity). Root distribution patterns were assessed by collecting roots within layers, each 10 cm depth, and by recording both the ﬁne (diameter &lt;2 mm) and the coarse (diameter 2 mm) root biomass. Root systems signiﬁcantly responded to the vertical gradients of soil bulk density, decreasing their maximum depth and showing lower values of ﬁne root densities at the layers with a dry bulk density of 1.62 Mg m3 . The split-root system showed that maximum rooting depth of the axis with a dry bulk density of 1.38 Mg m3 was limited by the reduced rooting depth of the adjacent more compacted axis. Root systems were less dense in the NH4 soil treatment than in the control soil treatment (34 mg dm3 vs. 212 mg dm3 ), even at the lowest rate used (0:1 g NH4 L 1 soil ). This high sensitivity to NH4 conducted to a signiﬁcant decrease of shoot height and root depth (50 and 43%, respectively). The split-root system showed that unfavourable conditions of NH4 content have local consequences on the rooting depth and systemic consequences on the ﬁne root density. The implications of root growth restrictions for Q. ilex natural regeneration, seedling survival, and decline are discussed.</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue></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%">Cubera, Elena</style></author><author><style face="normal" font="default" size="100%">Moreno, Gerardo</style></author><author><style face="normal" font="default" size="100%">Solla, Alejandro</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Quercus ilex root growth in response to heterogeneous conditions of soil bulk density and soil NH4-N content</style></title><secondary-title><style face="normal" font="default" size="100%">Soil and Tillage Research</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Oak decline</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Root density</style></keyword><keyword><style  face="normal" font="default" size="100%">Root depth</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil bulk density</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil NH4 content</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year></dates><volume><style face="normal" font="default" size="100%">103</style></volume><pages><style face="normal" font="default" size="100%">16-22</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">A greenhouse study examined the effects of heterogeneous conditions of soil bulk density and soil NH4-N content on the growth of holm oak (Quercus ilex L.) seedlings over an 8-month period. Heterogeneity of soil was produced inside 150 cm depth pots, by applying manual compaction or enriching different soil layers with NH4 (vertical heterogeneity) and, by splitting the root system into two columns with differing soil bulk density or NH4 conditions (horizontal heterogeneity). Root distribution patterns were assessed by collecting roots within layers, each 10 cm depth, and by recording both the ﬁne (diameter &lt;2 mm) and the coarse (diameter 2 mm) root biomass. Root systems signiﬁcantly responded to the vertical gradients of soil bulk density, decreasing their maximum depth and showing lower values of ﬁne root densities at the layers with a dry bulk density of 1.62 Mg m3 . The split-root system showed that maximum rooting depth of the axis with a dry bulk density of 1.38 Mg m3 was limited by the reduced rooting depth of the adjacent more compacted axis. Root systems were less dense in the NH4 soil treatment than in the control soil treatment (34 mg dm3 vs. 212 mg dm3 ), even at the lowest rate used (0:1 g NH4 L 1 soil ). This high sensitivity to NH4 conducted to a signiﬁcant decrease of shoot height and root depth (50 and 43%, respectively). The split-root system showed that unfavourable conditions of NH4 content have local consequences on the rooting depth and systemic consequences on the ﬁne root density. The implications of root growth restrictions for Q. ilex natural regeneration, seedling survival, and decline are discussed.</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%">Cubera, Elena</style></author><author><style face="normal" font="default" size="100%">Moreno, Gerardo</style></author><author><style face="normal" font="default" size="100%">Elena, C</style></author><author><style face="normal" font="default" size="100%">Gerardo, M</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effect of single Quercus ilex trees upon spatial and seasonal changes in soil water content in dehesas of central western Spain</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%">Oak woodland</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil water content</style></keyword><keyword><style  face="normal" font="default" size="100%">TDR</style></keyword><keyword><style  face="normal" font="default" size="100%">tree-grass interaction</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><volume><style face="normal" font="default" size="100%">64</style></volume><pages><style face="normal" font="default" size="100%">355-364</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The spatial and temporal evolution of soil water content () in Quercus ilex dehesas has been investigated to determine how trees modify the soil water dynamics and the nature of tree-grass interactions in terms of soil water use in these ecosystems. Soil physical parameters and were measured at different distances from the tree trunk (2-30 m) in the upper 300 cm of soil. was measured monthly by TDR during 2002-2005. Tree water potential was determined during the summers of 2004 and 2005. At deeper soil layers, mean values were higher beyond than beneath tree canopy during dry periods. depletion beyond tree canopy continued even in summer, when herbaceous plants dried up, suggesting that trees uptake water from the whole inter-tree space. Results have shown a high dependence of trees on deep water reserves throughout late spring and summer, which helps to avoid competition for water with herbaceous vegetation.</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%">Cubera, Elena</style></author><author><style face="normal" font="default" size="100%">Moreno, Gerardo</style></author><author><style face="normal" font="default" size="100%">Elena, C.</style></author><author><style face="normal" font="default" size="100%">Gerardo, M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effect of single Quercus ilex trees upon spatial and seasonal changes in soil water content in dehesas of central western Spain</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%">Oak woodland</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil water content</style></keyword><keyword><style  face="normal" font="default" size="100%">TDR</style></keyword><keyword><style  face="normal" font="default" size="100%">tree-grass interaction</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://dx.doi.org/10.1051/forest:2007012</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">64</style></volume><pages><style face="normal" font="default" size="100%">355 - 364</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The spatial and temporal evolution of soil water content () in Quercus ilex dehesas has been investigated to determine how trees modify the soil water dynamics and the nature of tree-grass interactions in terms of soil water use in these ecosystems. Soil physical parameters and were measured at different distances from the tree trunk (2-30 m) in the upper 300 cm of soil. was measured monthly by TDR during 2002-2005. Tree water potential was determined during the summers of 2004 and 2005. At deeper soil layers, mean values were higher beyond than beneath tree canopy during dry periods. depletion beyond tree canopy continued even in summer, when herbaceous plants dried up, suggesting that trees uptake water from the whole inter-tree space. Results have shown a high dependence of trees on deep water reserves throughout late spring and summer, which helps to avoid competition for water with herbaceous vegetation.</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue></record></records></xml>