A multiple approach for the evaluation of the spatial distribution and dynamics of a forest habitat: the case of Apennine beech forests with Taxus baccata and Ilex aquifolium

Abstract

An approach integrating phytosociological and stand structure surveys with the predictive modelling of species distribution was applied to analyse the spatial distribution and dynamics of the Apennine beech forests with Taxus and Ilex, a high conservation priority forest habitat in Europe. The homogeneity of the habitat was tested trough a Mann-Whitney test between beech woods with Taxus and those with Ilex with respect to climatic, topographic, structural and environmental parameters: the former have proven to be more microthermic, mesophilous and characterised by a closer canopy. Five statistical models were compared to analyse the relationship between bioclimatic parameters and Taxus and Ilex spatial distribution: Regression Tree Analysis, the most efficient model, has shown that the distribution of Taxus is influenced by precipitation variables, while Ilex is mainly influenced by temperature variables. This model highlighted that Ilex has a potential area that surrounds, at lower altitudes, that of Taxus. A stepwise multiple regression analysis has been applied to identify the factors influencing the regeneration of the two species: beside climatic parameters, Taxus regeneration is negatively influenced by soil nitrate concentration (an indicator of livestock disturbance) while Ilex is negatively influenced by beech forest cover. Traditional management practices seem to have an effect on the regeneration of the two species: frequent cuts favour the regeneration of Ilex, reducing the forest cover and allowing more light penetration, while Taxus, less resistant to grazing livestock, is confined to more inaccessible places. The multiple approach has proven to be useful for the elaboration of two differentiated conservation strategies for the two beech forest types

Natural regeneration and gender-specific spatial pattern of Taxus baccata in an old-growth population in Foresta Umbra (Italy)

“…Phillyreo latifoliae-Taxetum baccatae and Cyclamino repandi-Taxetum baccatae), in Calabria and Sicily (Ilici-Taxetum baccatae) (Brullo et al 1996(Brullo et al , 2001Bacchetta and Farris 2006;Farris et al 2012). In particularly humid conditions Taxus and Ilex can also be found at 500 m, relicts of the Cenozoic flora, characterised by warm-humid climatic conditions, survived the glaciations of the Quaternary period in refugial areas, and may have followed Fagus in the successive post glacial expansion (Magri et al 2006;Scarnati et al 2009). …”

Genetic diversity and population structure of the endangered conifer Taxus wallichiana var. mairei (Taxaceae) revealed by Simple Sequence Repeat (SSR) markers

“…Moreover, T. wallichiana was also recognized globally as endangered A2acd in the IUCN Red List of Threatened Species (Thomas and Farjon, 2011). In all species of Taxus L., T. baccata, the only species present in Europe, was studied systematically in conservation biology, population ecology and phylogeography (Piovesan et al, 2009;Scarnati et al, 2009;Dubreuil et al, 2010;González-Martíneza et al, 2010;Chybicki et al, 2011). As for T. wallichiana var.…”

A Bayesian Model for Presence-Only Semicontinuous Data, With Application to Prediction of Abundance of Taxus Baccata in Two Italian Regions

“…The area of interest extends for about 28,000 km 2 , with an heterogeneous morphology, which includes sandy coasts and the summits of the Apennines (the highest peak being the Gran Sasso, 2912 m of altitude). The forest habitat of Taxus baccata in these two regions is of high conservation priority in Europe (Scarnati et al 2009a).…”

“…There are many indices of abundance which could be used. In this research we have used the Importance Value (IV), for a definition of which we point the reader to Scarnati et al (2009a). In each selected location the IV of Taxus baccata was measured based equally on relative basal area and the number of stems contained within it.…”