Comparative analysis of species diversity of isopoda oniscidea and collembola communities in burnt and unburnt habitats in central italy

The structure and diversity of Isopoda and Collembola communities are described and compared in burnt and unburnt sites occupied by oak and pine forests within a Mediterranean coastal ecosystem in central Italy (near Rome) to assess the effect of fire on these soil arthropods. The community succession, starting just after the fire, proceeded differently in the examined sites, showing distinct ecological responses between Collembola and Isopoda, as evinced by cluster analysis among sites and comparisons of species abundances. The burnt oak forest communities, less damaged by fire, were quite different from the burnt pine forests, which had few species, usually more abundant in individuals. Examining the mean of the whole abundance of each site, particularly in isopods, burnt sites showed greatly reduced values in comparison with unburnt sites. Both springtail and isopod communities of burnt sites showed a continuous turnover, evidenced by both temporally restricted species and temporal variations in species richness determined by post-fire recolonisation. The species succession produced disequilibria of monthly and yearly abundances, which interacted with monthly variations in community structure determined by meteorological factors. The community structure stabilisation in burnt ecosystems during the succession is also demonstrated by the increasing of Shannon diversity and evenness values, particularly in Collembola. On the basis of temporal values of species richness and Shannon diversity values recorded for each site, two main patterns can be recognised: (1) oak forests were more diverse than pinewoods, and (2) unburnt sites were temporally more diverse than the burnt ones, because they host communities mostly subject to seasonal changes, especially due to some variations in humidity, rainfall and temperature. Burnt habitats tended to change their species composition more drastically, without any clear relationship with seasonally, because of the interaction of recolonisation with seasonal replacing of species, which determine a greater value of final “entropy”, as observed by the total annual values of Shannon diversity. © 2005 Taylor & Francis Group, LLC.