<?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%">Llorente, Mireia</style></author><author><style face="normal" font="default" size="100%">Glaser, Bruno</style></author><author><style face="normal" font="default" size="100%">Turrión, María-Belén</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Anthropogenic disturbance of natural forest vegetation on calcareous soils alters soil organic matter composition and natural abundance of 13C and 15N in density fractions</style></title><secondary-title><style face="normal" font="default" size="100%">European Journal of Forest Research</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%">density fractions</style></keyword><keyword><style  face="normal" font="default" size="100%">Land use change</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://www.springerlink.com/index/10.1007/s10342-010-0402-3</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">129</style></volume><pages><style face="normal" font="default" size="100%">1143 - 1153</style></pages><isbn><style face="normal" font="default" size="100%">1034201004023</style></isbn><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In the last century, many calcareous soils in Castilla Leo´n (northwestern Spain) have been transformed from natural Quercus ilex forest to cropped land. Reforestation with Pinus halepensis has been taking place during the past 40 years. In order to obtain a better understanding of how these disturbances affect ecosystem functioning, we studied the quantity and quality of soil organic matter (SOM) in natural forest ecosystems, cropland and Pinus plantations. Density fractionation combined with ultrasonic dispersion enables separation and study of SOM fractions: free organic matter (OM), OM occluded into aggregates and OM stabilized in organo-mineral complexes, considered on the basis of the type of physical protection provided. We separated SOM density fractions and determined the concentrations of C and N, C/N ratios and the natural isotopic abundance (d 13 C and d 15 N values). Transformation of Quercus forest to cropland resulted in major losses of SOC and N, as expected. However, subsequent reforestation with Pinus resulted in good recovery of the original SOC and soil N pools. This indicates the potential for enhanced C storage in agricultural soils by their reversion to a forested state. Study of the density fractions and their 13 C and 15 N signatures enabled better understanding of the high stability of OM in calcareous soils, and analysis of d 13 C variations throughout the proﬁle also enabled identiﬁcation of past C3/C4 vegetation change. Despite the different OC contents of soils under different land use, OM stabilization mechanisms were not signiﬁcantly different. In calcareous soils, accumulation of SOC and N is mainly due to organo-mineral associations, resulting in physicochemical stabilization against further decomposition.</style></abstract><issue><style face="normal" font="default" size="100%">6</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%">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></records></xml>