<?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%">Casals, Pere</style></author><author><style face="normal" font="default" size="100%">Garcia-Pausas, Jordi</style></author><author><style face="normal" font="default" size="100%">Montané, Francesc</style></author><author><style face="normal" font="default" size="100%">Romanyà, Joan</style></author><author><style face="normal" font="default" size="100%">Rovira, Pere</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Root decomposition in grazed and abandoned dry Mediterranean dehesa and mesic mountain grasslands estimated by standard labelled roots</style></title><secondary-title><style face="normal" font="default" size="100%">Agriculture, Ecosystems &amp; Environment</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">13C</style></keyword><keyword><style  face="normal" font="default" size="100%">15N</style></keyword><keyword><style  face="normal" font="default" size="100%">Grazing exclusion</style></keyword><keyword><style  face="normal" font="default" size="100%">Shrub encroachment</style></keyword><keyword><style  face="normal" font="default" size="100%">Subalpine grasslands</style></keyword><keyword><style  face="normal" font="default" size="100%">Tracer techniques</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2010///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://linkinghub.elsevier.com/retrieve/pii/S0167880910002811</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">139</style></volume><pages><style face="normal" font="default" size="100%">759 - 765</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Because root turnover represents the major source for building up soil organic matter in ecosystems with high belowground allocation, like grasslands, sensitive analyses on root decomposition rates may contribute to point out the effect of grazing abandonment on soil C and N dynamics. The objective was to detect changes in root C and N mineralization due to pasture abandonment in Mediterranean dehesa mountain grasslands. Root decomposition was estimated by ﬁeld incubation of 13 C- and 15 N-labelled wheat roots mixed with unlabelled soil over one year at 5 cm depth in grazed and short-term excluded grasslands in three contrasting situations: (i) a Mediterranean dehesa, (ii) altimontane and (iii) subalpine sites. In addition, the long-term effect of grazing abandonment was estimated in a subalpine shrub encroached site. Overall, root decomposition rates decrease from Mediterranean to mountain sites. Moreover, on mountain sites, either grazing exclusion or shrub encroachment reduced 13 C losses from root–soil bags in about four to seven percentage units; in contrast, such an effect was not detected in the Mediterranean grassland. The dynamics of 15 N derived from root–soil bags was site-dependent without a clear pattern related to site climate or grazing abandonment. In general, the fate of mineralized root-N, leached or immobilized in the surrounding soil, seems to be related to soil variables such as the C:N ratio.</style></abstract><issue><style face="normal" font="default" size="100%">4</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: Elsevier B.V.</style></notes></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%">Grasset, Laurent</style></author><author><style face="normal" font="default" size="100%">Rovira, Pere</style></author><author><style face="normal" font="default" size="100%">Amblès, André</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">TMAH-preparative thermochemolysis for the characterization of organic matter in densimetric fractions of a Mediterranean forest soil</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Analytical and Applied Pyrolysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">carbohydrates</style></keyword><keyword><style  face="normal" font="default" size="100%">Density fractionation</style></keyword><keyword><style  face="normal" font="default" size="100%">fatty acids</style></keyword><keyword><style  face="normal" font="default" size="100%">Lignin subunits</style></keyword><keyword><style  face="normal" font="default" size="100%">mediterranean forest soils</style></keyword><keyword><style  face="normal" font="default" size="100%">Thermochemolysis</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year></dates><volume><style face="normal" font="default" size="100%">85</style></volume><pages><style face="normal" font="default" size="100%">435-441</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Physical protection is one of the most important ways for stabilization of organic carbon in soils, and in order to properly manage soils as a sink for carbon, it is necessary to know how much organic carbon a given soil could protect and to have information on the molecular composition of this protected organic matter in soil. To this end, we studied individual horizons taken from a soil proﬁle under Quercus rotundifolia stands over calcareous parent material. Horizons were subjected to a sequential extraction using solutions of sodium polytungstate (NaPT) of increasing density (1.6, 1.8 and 2.0) to differentiate ﬁve fractions: a free light, extractable without sonication, three occluded (extractable by sonication) and a dense (retained in the dense residue, after sonication). The obtained fractions were analyzed by preparative thermochemolysis followed by gas chromatography–mass spectrometry (GC/MS) in order to get some insight on the molecular composition. The total ion chromatograms obtained for the pyrolysates of both of the densimetric fractions show various series of fatty acids (as their methyl esters), n-alkanols (as their methyl ethers), methylated a,v-diacids, methylated v-hydroxyacids, various lignous subunits and permethylated deoxy aldonic acids derived from carbohydrates. The comparison of the distributions of the thermochemolysis products shows that organic carbon in the dense fractions of the deepest horizons were more inﬂuenced by a microbial reworking than the others dense fractions from the upper horizons. It is also the case for the occluded fraction 1 of the H horizon even the vegetal part of the organic carbon in that occluded fraction appears to have a non-woody origin. On the other hand, the dense fraction of the H horizon is strongly marked by vegetal origin.</style></abstract></record></records></xml>