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Are drought and wilfires turning Mediterranean cork oak forests into persistent shrublands ?
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Orientador(es)
Resumo(s)
In the Iberian Peninsula Mediterranean
oak forests have been transformed into a mosaic
landscape of four main patch-types: forests, savannas,
shrublands and grasslands. We used aerial photographs
over a period of 45 years (1958–2002) to
quantify the persistence and rates of transitions
between vegetation patch-types in southern Portugal,
where cork oak is the dominant tree species. We used
logistic regression to relate vegetation changes with
topographical features and wildfire history. Over the
45 years, shrublands have been the most persistent
patch-type (59%), and have been expanding; forests
are also persistent (55%) but have been decreasing
since 1985; savannas and grasslands were less
persistent (33% and 15%, respectively). Shrublands
persistence was significantly correlated with wildfire
occurrence, particularly on southern exposures after
1995. In contrast, forest persistence decreased with wildfire occurrence, and forests were more likely to
change into shrublands where wildfire had occurred
after 1995.
Descrição
Palavras-chave
alternative stable states Cistus shrub encroachment vegetation shifts Quercus suber
Contexto Educativo
Citação
"Agroforestry Systems". ISSN 0167-4360. 76 (2009) 389-400