Quantitative floristics as a tool for the assessment of plant diversity in Tuscan forests

The results of a floristic survey in six forests owned and managed by the regional administration of Tuscany are reported in this paper. These forests are undergoing a monitoring program, which includes biodiversity as one of the status indicators. Vascular plants are used as indicator species group to quantify biodiversity and they are assessed by means of quantitative floristics. This approach involves the collection of floristic information on the basis of a sampling design. Floristic and structural data were collected in 109 plots, each 400 m2 large, and analysed at both the plot and forest scales. At the plot scale, species richness was found to be unimodally related to elevation and negatively related to tree stem density and total basal area. At the forest scale, the six forests differed in their patterns of species accumulation, with the highest number of species for a given number of sites sampled observed in the intermediate elevation forests. The analysis of the life-form spectrum showed, for both the plot and forest scales, a decreasing importance of the relative abundance of phanerophytes and an increasing importance of the relative abundance of hemicriptophytes in relation to elevation. The use of the approach adopted for future monitoring is also discussed.