Beja, Rui Pedro Correia de OliveiraSantana, Joana Figueiredo2009-07-102009-07-102009http://hdl.handle.net/10400.5/1112Mestrado em Gestão de Recursos Naturais - Instituto Superior de AgronomiaThe increased usage of mechanical understorey clearing in Mediterranean forests to reduce fire risk has consequences on biological communities that are poorly known. This issue was addressed using a chronosequence of 48 Quercus suber forest stands in southern Portugal, to estimate how vegetation and bird assemblages attributes change following clearing over about 70 years. This study showed that understorey clearing has long-lasting effects on vegetation structure and composition, as well as on bird assemblages, that lasted for at least 40-50 years. Recovery of tree richness lasted about 50 years. Shrubs started recovering immediately after clearing, with pioneer seeder species dominating understorey vegetation for about 20 years. Resprouter species recovered slowly for about 40-50 years. Both breeding and wintering bird assemblages were affected by clearing, with particularly strong effects on insectivorous and frugivorous species, mostly those associated with shrubs and trees. Results were stronger during winter when frugivores distribution appeared influenced by fruit tracking in old understorey forests. Vertical heterogeneity in old understorey stands was likely to be the key factor affecting bird distribution during spring. Management strategies for reducing fire risk should strive to maintain some stands with understorey older than about 50 years in order to conserve biodiversity repositories.porcork oak forestsfire riskforest managementvegetation recoverfruit trackingmosaic systemsobreiraisrisco de incêndiogestão florestalrecuperação da vegetaçãofrugivorossistema em mosaicomaster thesis