| Přispěvatelé: |
Valerio Amici, Elisa Santi, Goffredo Filibeck, Martin Diekmann, Francesco Geri, Sara Landi, Anna Scoppola, Alessandro Chiarucci |
| Popis: |
Aim As a consequence of multiple cycles of deforestation and reforestation,most forest landscapes in Europe consist of a complex mosaic of patches ofdifferent successional ages. Despite the biogeographical distinctiveness of theMediterranean region, studies on the effects of forest age on plant speciesdiversity and composition are almost lacking for this area. This paper evaluatesthe influence of forest successional age on plant species richness and composi-tion in various forest types of Mediterranean Italy.Location The Natura 2000 network of Siena Province, Tuscany, Italy.Methods Occurrence data on vascular plant species in 208 forest plots wereobtained from a larger data set sampled with a stratified random design. Theforest successional age of each plot was quantified through a series of historicalmaps. Species richness and composition were related to the age of the forestby means of GIS techniques and univariate and multivariate statistical analyses.Results Total species richness markedly decreased with increasing successionalage due to a significant decrease in the richness of open-habitat species whichwas not matched by increasing richness of mature forest species. Successionalage was the key factor in controlling species richness, while local environmentalproperties emerged as the main factors shaping community composition. Thedifferent forest types showed different temporal trends of species richness andcomposition and different hierarchies of explanatory factors.Main conclusions Forest successional age emerged as an important factoraffecting both species richness and composition, even within the same foresttype. Thus, the classification and prioritization of Mediterranean forests exclu-sively based on present physiognomy or environmental variables causes loss ofinformation about species richness and composition; this could be detrimentalfor biodiversity conservation.KeywordsCommunity composition, Italy, land-use change, Mediterranean forests, Natura2000, species richness, successional age, Tuscany, variation partitioning.INTRODUCTIONMost present-day European forests have been subject to sig-nificant changes for centuries or millennia, with many forestshaving been cleared, converted into farmland and thenabandoned again allowing for forest regeneration (Reischet al., 2007). The history of land-use change has includedperiods of intense deforestation with the rise of powerfulcivilizations, as in Roman times or during the Renaissance(Crumley, 1994; Scarascia-Mugnozza et al., 2000), as well asperiods of land abandonment and reforestation, as in theearly Middle Ages in southern Europe (Behre, 1988; Crum-ley, 1994). The most recent deforestation cycle started in the19th and 20th centuries, when the Industrial Revolutionresulted in an increase in human population (Pongratz et al.,2008; Ellenberg & Strutt, 2009). This was followed by socio-economic changes after World War II causing significantchanges in land-use in most European landscapes, including |
