<?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%">Gonzalez Parra, J</style></author><author><style face="normal" font="default" size="100%">Candás Villar, M A</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Materia orgánica de suelos bajo encinas. Mineralización de carbono y nitrógeno</style></title><secondary-title><style face="normal" font="default" size="100%">Forest Systems</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">organic matter</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus rotundifolia</style></keyword><keyword><style  face="normal" font="default" size="100%">soils</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2008</style></year></dates><volume><style face="normal" font="default" size="100%">13</style></volume><pages><style face="normal" font="default" size="100%">75-83</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Soil characteristics under evergreen oaks forest (Quercus rotundifolia Lam.) located at the East of Segovia were studied. The soils were formed from gneis and limestone. The whole soil was 0-20 cm depth. The soils were classified as mollic Leptosols, eutric Cambisols and calcaric Cambisols. Horizons sequences were the following: O, Ah1, Ah2, C and O, Ah1, Ah2, BC. Organic horizons (3-0 cm depth) were formed by the not-yet decomposed organic remains from evergreen oaks. Mean organic matter content was 25%. The C:N ratio was high and free organic carbon was near 90% of the total carbon, which correspond with a low degree of humification. Soil texture was loamy sand and sandy loam. Soils on limestone present the highest clay fraction contents. The bases saturation degree was high, being Ca 2+ the fundamental cation of exchange complex. Organic matter content and C:N ratio were lower in organic minerals horizons than in organic horizons. Humification degree was 60% with a predominance of HAs over FAs. The polimerization of humic substances makes possible the formation of humus «moder». Carbon mineralization to the total C was ten times higher than nitrogen mineralization in upper horizons. In all horizons the nitrification was higher than N mineralization. Carbon mineralization was lower and N mineralization was higher in deeper horizons compearing with upper horizons.</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%">Rovira, P.</style></author><author><style face="normal" font="default" size="100%">Vallejo, V. R.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Organic carbon and nitrogen mineralization under Mediterranean climatic conditions: the effects of incubation depth</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Biology and Biochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword><keyword><style  face="normal" font="default" size="100%">organic matter (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil depth</style></keyword><keyword><style  face="normal" font="default" size="100%">water content</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1997</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1997///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0038071797000527</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">29</style></volume><pages><style face="normal" font="default" size="100%">1509 - 1520</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">n a soil profile, temperature and humidity regimes change with depth. Under Mediterra- nean conditions, upper horizons are more affected by water deficits and drying-rewetting cycles than deep horizons. Our aim was to study how carbon and nitrogen mineralization are affected by depth, and special attention is paid to separating the effects of pedoclimate from the effects of other con- straints like amount and quality of organic matter. To this end, mixtures of plant + soil material were exposed by incorporation in the field, at depths of 5, 20 and 40 cm, in nylon mesh bags. Mineralization of C and N was studied for 2 y. For all types of plant material studied (Eucalyptus globulus, Quercus ibex and Pinus halepensis), mineralization of both carbon and nitrogen was lower at 5cm. No differ- ences were between 20 and 40 cm. This result, probably as a result of the higher drying of the upper- most horizons, contrasts with the usual findings on this topic. The amounts of both C and N mineralized were lower than expected, probably because plant materials were finely ground, allowing stabilization in the mineral matrix of soil. With the possible exception of Pinus, depth affected the rate of mineralization, not the relation between C and N. It is concluded that, at least under Mediterranean conditions, the pedoclimate in deep layers is more favourable to microbial activity than in upper layers, in which drought is a strong limiting factor. Reduced oxygen availability in the subsoil layers did not inhibit decomposition and mineralization to the same extent as did desiccation in the surface layer. The higher mineralization of C and N usually found in upper horizons may be attributed to the higher amount and quality of organic matter in these horizons, rather than to pedoclimatic constraints</style></abstract><issue><style face="normal" font="default" size="100%">9110</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%">Rovira, P</style></author><author><style face="normal" font="default" size="100%">Vallejo, V R</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Organic carbon and nitrogen mineralization under Mediterranean climatic conditions: the effects of incubation depth</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Biology and Biochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword><keyword><style  face="normal" font="default" size="100%">organic matter (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">Soil depth</style></keyword><keyword><style  face="normal" font="default" size="100%">water content</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1997</style></year></dates><volume><style face="normal" font="default" size="100%">29</style></volume><pages><style face="normal" font="default" size="100%">1509-1520</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">n a soil profile, temperature and humidity regimes change with depth. Under Mediterra- nean conditions, upper horizons are more affected by water deficits and drying-rewetting cycles than deep horizons. Our aim was to study how carbon and nitrogen mineralization are affected by depth, and special attention is paid to separating the effects of pedoclimate from the effects of other con- straints like amount and quality of organic matter. To this end, mixtures of plant + soil material were exposed by incorporation in the field, at depths of 5, 20 and 40 cm, in nylon mesh bags. Mineralization of C and N was studied for 2 y. For all types of plant material studied (Eucalyptus globulus, Quercus ibex and Pinus halepensis), mineralization of both carbon and nitrogen was lower at 5cm. No differ- ences were between 20 and 40 cm. This result, probably as a result of the higher drying of the upper- most horizons, contrasts with the usual findings on this topic. The amounts of both C and N mineralized were lower than expected, probably because plant materials were finely ground, allowing stabilization in the mineral matrix of soil. With the possible exception of Pinus, depth affected the rate of mineralization, not the relation between C and N. It is concluded that, at least under Mediterranean conditions, the pedoclimate in deep layers is more favourable to microbial activity than in upper layers, in which drought is a strong limiting factor. Reduced oxygen availability in the subsoil layers did not inhibit decomposition and mineralization to the same extent as did desiccation in the surface layer. The higher mineralization of C and N usually found in upper horizons may be attributed to the higher amount and quality of organic matter in these horizons, rather than to pedoclimatic constraints</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%">Cortez, J</style></author><author><style face="normal" font="default" size="100%">Demard, J M</style></author><author><style face="normal" font="default" size="100%">Bottner, P</style></author><author><style face="normal" font="default" size="100%">Jocteur Monrozier, L</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Decomposition of mediterranean leaf litters: A microcosm experiment investigating relationships between decomposition rates and litter quality</style></title><secondary-title><style face="normal" font="default" size="100%">Soil Biology and Biochemistry</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cellulose</style></keyword><keyword><style  face="normal" font="default" size="100%">decomposition</style></keyword><keyword><style  face="normal" font="default" size="100%">hemicellulose</style></keyword><keyword><style  face="normal" font="default" size="100%">leaf litter</style></keyword><keyword><style  face="normal" font="default" size="100%">Lignin</style></keyword><keyword><style  face="normal" font="default" size="100%">litter quality (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">mass loss</style></keyword><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1996</style></year></dates><volume><style face="normal" font="default" size="100%">28</style></volume><pages><style face="normal" font="default" size="100%">443-452</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">he decomposition of four mediterranean species leaf litter (Sessile oak, Quercus petraea L.; Holm oak, Quercus ibex L.; Sweet chestnut, Castanea satiua Mill and beech, Fagus syluatica L.) was studied for 90 days under controlled conditions. Respiration and litter mass loss were measured in three types of microcosms: (1) Soil only; (2) Soil + l-y old litter and (3) Soil + l-y old litter + newly senescent litter (freshly fallen). Variations in chemical composition of the litters were determined before and after incubation by the pyroanalysis method. For newly senescent litters decomposition rates per day Kco, (calculated from CO, release) and K, (calculated from mass losses) fitted to the first order exponential decay decreased as follows: sessile oak (Kc,_,, = 0.0043; K, = 0.0049) &gt; holm oak (Km, = 0.0031; K, = 0.0040) = beech (&amp;o~ = 0.0030; K, = 0.0030) &gt; sweet chestnut (Kc% = 0.0001; K,, = non- significant regression); For l-y old litters sweet chestnut (Ko,, = O.oo40, K, = 0.0065) &gt; sessile oak (KEO, = 0.0035; K, = 0.0039) &gt; beech (Kcc,, = 0.0030; K, = non-significant regression). All litters showed a reduction of lipid (mean loss 90.5%), hydrosoluble (mean loss, 54.2%), hemicellulose plus cellulose (mean loss, 40.6%) content and a relative increase of lignin content (mean gain, 34.4%). Among indicators of litter quality (C-to-N ratio, %N, %lignin, lignin-to-N ratio, HLQ), only some of them were correlated with litter decay. The best relationships were established between the decomposition rates (K,) and parameters integrating lignin contents (I = 0.997; n = 3; P &lt; 0.01). The decomposition of l-y old litters fitted well with most of these parameters (0.999 &lt; I &lt; 0.997; n = 3; P &lt; 0.01) in contrast to newly senescent litters</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%">van Wesemael, Bas</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Litter decomposition and nutrient distribution in humus profiles in some mediterranean forests in southern Tuscany</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%">forest types</style></keyword><keyword><style  face="normal" font="default" size="100%">litter decomposition</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean forest (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword><keyword><style  face="normal" font="default" size="100%">nutrient concentration</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1993</style></year></dates><volume><style face="normal" font="default" size="100%">57</style></volume><pages><style face="normal" font="default" size="100%">99-114</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Decomposition of leaf litter and the distribution of elements in the humus layer were studied in mediterranean deciduous, sclerophyllous and coniferous forests on acid rocks. The results indicate a clear difference in relative decomposition rate between pine needles (Pinus pinaster: 0.12 year−1) and leaves of deciduous and sclerophyllous species (Quercus cerris, Quercus suber and Arbutus unedo: 0.30 year−1). The concentrations of N, P, S and Ca increase upon decomposition, whereas that of K decreases by initial leaching, and those of Mg, Mn (Fe, Al) remain unchanged except for an increase resulting from mineral contamination. In deciduous and sclerophyllous litter, absolute amounts of N, P, S and Ca increase until a critical concentration level is reached, after which net mineralization occurs. For pine needles net mineralization was not observed within 915 days. In analogy with the situation during the litter bag experiments, elemental concentrations are highest in the lower more decomposed part of the humus profiles. In deciduous and sclerophyllous forests net mineralization of N, P, S and Ca starts in the lower part of the fermentation layer. In the coniferous forest elemental concentrations are much lower and no indications of N, P, S and Ca mineralization were found in the ectorganic horizons.</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%">Rashid, G H</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Effects of fire on soil carbon and nitrogen in a Mediterranean oak forest of Algeria</style></title><secondary-title><style face="normal" font="default" size="100%">Plant and Soil</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">forest soil</style></keyword><keyword><style  face="normal" font="default" size="100%">mineralization</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">pH</style></keyword><keyword><style  face="normal" font="default" size="100%">Wildfire</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1987</style></year></dates><volume><style face="normal" font="default" size="100%">103</style></volume><pages><style face="normal" font="default" size="100%">89-93</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The effects of wildfire on the dynamics of pH, organic C, total and mineral N and in vitro C and N mineralization were investigated in the soil under oak (Quercus suber L.) trees. Soil samples were taken from 5 to 21 months subsequent to the fire. The pH increased sharply in the burned surface soil (0-5 cm) taken 5 months after the fire and dropped only by half a unit over 14 to 21 months. However, at greater depth (5-15 cm), the burned soil was more acidic than the adjacent unburned soil up to 9 months following the fire, and thereafter its pH rose only slightly above that of the unburned soil. There were sharp rises in the concentration of organic C, total and mineral N in addition to in vitro mineralization activities in the burned surface soil collected 5 months after the fire; these dropped off in the subsequent samples approaching or falling below the values obtained in the unburned surface soil after 21 months. At a depth of 5-15 cm only slight or no increases over unburned soil were evident.</style></abstract></record></records></xml>