Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Master → Portugal → Erosão e exportação de matéria orgânica do solo em áreas ardidas

Universidade de Aveiro (2011)

Erosão e exportação de matéria orgânica do solo em áreas ardidas

Caria, Maria Margarida Pereira Faria de

Titre : Erosão e exportação de matéria orgânica do solo em áreas ardidas

Auteur : Caria, Maria Margarida Pereira Faria de

Université de soutenance : Universidade de Aveiro

Grade : Mestrado em Engenharia do Ambiente 2011

Résumé
Burnt soils are more susceptible to erosion, as a consequence of the disappearance of the topsoil caused by wildfires and also due to changes in physical and chemical characteristics of the soil itself, namely, in repellence, porosity and structure. Portugal, due to features as the aridity of soil and irregular and intense rainfall, is included in the context of soil degradation, given the high risk of fire associated to Mediterranean countries. In this study, framed in the project FIRECNUTS (PTDC/AGR-CFL/104559/2008), hydric exportation of soil’s organic matter was analysed, as a consequence of the fire that occurred in the 26th of July in 2010, in Ermida, district of Aveiro, in the Central-North region in Portugal. The burnt area had about 295 ha. Inside this area 3 slopes were selected, 2 eucalypt plantations with different geology (granite and schist) and a pine plantation (schist) for the study of the effects over different types of geology and woodlands. Outside the burnt area, was also selected an unburned eucalypt plantation (schist), as a basis of comparison, to evaluate the effect of the fire. In each of the slopes were installed tanks to collect run-off, four at slope-scale and three at micro-plot scale, with the exception of the unburned area that only had slope-scale plots. Besides this installation, soils were characterized at the level of organic matter, texture and bulk density. The weekly monitoring began approximately one month after the fire and lasted 6 months. The results indicate, at micro-scale, increased risk of erosion on soils upon schist (259g.m-2) than in soils upon granite (63 gm-2), and less risk of erosion in the pine forest (27 gm-2). The results, at slope-scale, suggest an opposite behaviour in the comparison between eucalypt plantations (granite and schist) (485 vs 36 g.m-2), and similar behaviour when comparing eucalypt plantations (schist) with pine forest (schist) (36 vs 6 g.m-2). The unburned slope shows that fire increases erosion, just as higher scales seem to reduce the risk of erosion, as a result of bigger interference, more contact time and run-off loss. It can be also verified that the organic matter levels remain constant over the time, in all slopes and at both scales (about 60%).

Présentation

Version intégrale (2,47 Mb)

Page publiée le 13 avril 2020