Impact of woody encroachment on soil organic carbon and nitrogen in abandoned agricultural lands along a rainfall gradient in Italy

Land use changes represent one of the most important components of global environmental change andhave a strong influence on carbon cycling. As a consequence of changes in economy during the last century, areas of marginal agriculture have been abandoned leading to secondary successions. The encroachment of woody plants into grasslands, pastures and croplands is generally thought to increase the carbon stored in these ecosystems even though there are evidences for a decrease in soil carbon stocks after land use change. In this paper, we investigate the effects of woody plant invasion on soil carbon and nitrogen stocks along a precipitation gradient (200–2,500 mm) using original data from paired experiment in Italian Alps and Sicily and data from literature (Guo and Gifford Glob Change Biol 8(4):345–360, 2002). We found a clear negative relationship (-0.05% C mm-1) between changes in soil organic carbon and precipitation explaining 70% of the variation in soil Cstocks after recolonization: dry sites gain carbon (up to? 67%) while wet sites lose carbon (up to -45%). In our data set, there seem to be two threshold values for soil carbon accumulation: the first one is 900 mm of mean annual rainfall, which separates the negative from the positive ratio values; the second one is 750 mm, which divides the positive values in two groups of sites. Most interestingly, this threshold of 750 mm corresponds exactly to a bioclimatic threshold: sites with\750 mm mean annual rainfall is classified as thermo-mediterranean sites, while the ones [750 mm are classified as mesomediterranean sites. This suggests that apart from rainfall also temperature values have an important influence on soil carbon accumulation after abandonment. Moreover, our results confirmed that the correlation between rainfall and trend in soil organic carbon may be related to nitrogen dynamics: carbon losses may occur only if there is a substantial decrease in soil nitrogen stock which occurs in wetter sites probably because of the higher leaching

Brittle fracture characteristics of welded joints in a higher strength steel for gas transmission pipelines (VZ 49N)

18.00; Translated from Czech (Zvaranie 1988 v. 37(5) p. 136-138)SIGLEAvailable from British Library Document Supply Centre- DSC:9023.19(VR--3549)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Evaluation of the brittle fracture resistance of gas transmission pipes damaged in insulation

18.00; Translated from Czech (Zvaranie 1988 v. 37(3) p. 79-82)SIGLEAvailable from British Library Document Supply Centre- DSC:9023.19(VR--3544)T / BLDSC - British Library Document Supply CentreGBUnited Kingdo

(2007) Secondary successions on meadows in eastern prealps: carbon balance in some case studies

Poster presentato in occasione della European Science Foundation Final Conference “The Role of Soils in the Terrestrial Carbon Balance” 20.-22. November 2007, Abbaye des Prémontrés, Pont-à-Mousson, Franc

Impact of woody encroachment on soil organic carbon and nitrogen in abandoned agricultural lands along a rainfall gradient in Italy

Land use changes represent one of the most important components of global environmental change and have a strong influence on carbon cycling. As a consequence of changes in economy during the last century, areas of marginal agriculture have been abandoned leading to secondary successions. The encroachment of woody plants into grasslands, pastures and croplands is generally thought to increase the carbon stored in these ecosystems even though there are evidences for a decrease in soil carbon stocks after land use change. In this paper, we investigate the effects of woody plant invasion on soil carbon and nitrogen stocks along a precipitation gradient (200-2,500 mm) using original data from paired experiment in Italian Alps and Sicily and data from literature (Guo and Gifford Glob Change Biol 8(4):345-360, 2002). We found a clear negative relationship (-0.05% C mm -1) between changes in soil organic carbon and precipitation explaining 70% of the variation in soil C stocks after recolonization: dry sites gain carbon (up to +67%) while wet sites lose carbon (up to -45%). In our data set, there seem to be two threshold values for soil carbon accumulation: the first one is 900 mm of mean annual rainfall, which separates the negative from the positive ratio values; the second one is 750 mm, which divides the positive values in two groups of sites. Most interestingly, this threshold of 750 mm corresponds exactly to a bioclimatic threshold: sites with 750 mm are classified as mesomediterranean sites. This suggests that apart from rainfall also temperature values have an important influence on soil carbon accumulation after abandonment. Moreover, our results confirmed that the correlation between rainfall and trend in soil organic carbon may be related to nitrogen dynamics: carbon losses may occur only if there is a substantial decrease in soil nitrogen stock which occurs in wetter sites probably because of the higher leaching. \ua9 2011 Springer-Verlag

Potere, autorit\ue0, formazione. Dinamiche socio-culturali

Il tema del \u201cPotere" presenta molteplici sfaccettature e vasti significati; appare complesso e ambiguo, bisognevole di continui approfondimenti di tipo filosofico, psicologico, linguistico, giuridico, economico, sociologico, politico, religioso. Nell\u2019esercizio del potere si compongono due forme, quella della capacit\ue0 effettiva, ma anche quella della coercizione e del dominio che, compresenti in una mescolanza complessa, possono in ogni momento sostituirsi una con l\u2019altra. Sulla scorta del pensiero di R. Guardini, serve considerare che \u201cil potere in s\ue9 e per s\ue9 considerato non \ue8 n\ue9 buono n\ue9 cattivo"; esso trova occasione di precisazione nelle persone e negli spazi in cui si incarna e non va confuso con l\u2019autorit\ue0, anche se la richiede. Nel riconoscere tali questioni, i contributi presenti nel volume sottolineano i significati positivi, diversamente declinati nel tempo come "potenza", "efficacia", "capacit\ue0 di", "empowerment", e approfondiscono la difficile e pur necessaria relazione tra potere e educazione che, nella molteplicit\ue0 dei luoghi in cui l\u2019educazione si mostra, risulta sempre contrassegnata dall\u2019elemento comune della relazione di tipo complementare tra colui che esercita il potere e colui che lo subisce