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Llorente M.,Centro Tecnologico Forestal Of Catalonia | Glaser B.,Martin Luther University of Halle Wittenberg | Turrion M.-B.,University of Valladolid
Soil Biology and Biochemistry | Year: 2017

In the last century, many calcareous soils in Castilla León (northwestern Spain) have been transformed from natural Quercus ilex forest to cropped land. During the past 40 years, cropping was abandoned and some of these soils has been reforested with Pinus halepensis. We studied how thEse land use changes affected the soil organic matter amount (C stocks) and characteristics. Density fractionation combined with ultrasonic dispersion enables separation and study of soil OM fractions, considered on the basis of the mechanisms of physical protection: non-physically protected OM (FF), OM occluded into aggregates (OF), and OM stabilized in organo-mineral complexes (DF). In the present study, whole soils and density fractions were analyzed for organic C amount (OC) and for carbohydrate content. The study aimed to describe the carbohydrate content in whole soils and its SOM density fractions to find out whether the carbohydrates can be used to explain the origin of SOM fractions and if they can depict its response to land management. We found a loss of 67% of the topsoil OC as a result of converting the natural Quercus ilex forest to cropped land, ∼100 years ago. After crop abandonment and soil reforestation with Pinus halepensis, the stock of topsoil OC increased. After ∼40 years of pine plantation, an average recovery of 71% of the previously lost OC had been recovered (43% loss of reference topsoil). The changes in OC stocks affected mainly the free fraction (FF) but also the organo-mineral (DF) one. Our results point to the role of physical protection in the C stocks but also that organo-mineral associations could be disrupted under a land use change. Monosaccharide content was significantly different (p < 0.01) among land uses. Gas chromatography analysis revealed significant differences in monosaccharide composition between land uses and also among density fractions. Whatever the fraction and land use considered, glucose was the dominant sugar monomer, followed by mannose and xylose. © 2017 Elsevier Ltd

Vega-Garcia C.,University of Lleida | Burriel M.,Centro Tecnologico Forestal Of Catalonia | Alcazar J.,University Leida
Forest Systems | Year: 2011

Methods tested in other countries are applied for scenic beauty valuation in several beech locations in Catalonia including significant differences in site, origin, age and stand structure. The study intends to measure stand scenic beauty as seen from inside the forest, as forest visitors see it (near-view). Assessments are obtained through panels of observers in slide sessions, which are transformed into scaled ratings and related through regression analysis to plot-based forest inventory data. The development of statistical models that describe social visual preferences allows the assessment of the contribution of different forestry-related physical variables to the aesthetic improvement of beech forests. It can also be useful as a guide to beech forest planning where recreational use is prevailing or very important.

Lopez R.,University of Lleida | Vericat D.,University of Lleida | Vericat D.,Centro Tecnologico Forestal Of Catalonia | Vericat D.,Aberystwyth University | And 3 more authors.
Tecnologia y Ciencias del Agua | Year: 2015

The lower Ebro River (NE Iberian peninsula) has a gravel bed which flows downstream from a reservoir complex. In this section of the river, the armoured surface of the bed undergoes cycles of breaking and reestablishment as a result of natural and control floods. The objective of the present work is two-fold. First, to evaluate the capacity of three formulas to predict bed load transport under conditions in which the armour is broken or disturbed. Second, to analyze the ability of the formulas to predict the breakage or disturbance threshold of the armour. This was all based on a comparison between predictions and measurements of the bed load transport in the study section for two hydrological years. Based on the characteristics of the study section, the formulas which were finally selected were the equations developed by Parker, Klingeman and McLean (1982) (P-K-M), Bathurst (2007) (B) and Recking (2010) (R). Given the results, the P-K-M and R formulas are recommended t predict bed load transport when there is breakage or disturbance of the amour, and not formula B because of its considerable tendency to underestimate. Formulas B and R are recommended to predict the breakage or disruption threshold of the armour. Nevertheless, it is worth cautioning that in this case both formulas tended to predict thresholds much lower than those measured. © 2015 Tecnología y Ciencias del Agua.

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