Phenological and floristic diversity in agroecosystems: some cases in Emilia-Romagna

The aim of this study was to investigate the plant biodiversity of semi- and sub-natural vegetation in the intensively cropped plain area of the Emilia-Romagna region. These coenoses (hedgerows between crops, herb margins and strips, ditch banks), where the soil is not exploited, represent valuable reservoirs of biodiversity which are under continuous threat. With the aim of evaluating the contribution of these communities to the biodiversity of agrecosystems, phytosociological and symphenological surveys were conducted in three sites: A) in the lowlands of Emilia (Modena-Reggio Emilia), B) in the area at the foot of the hills between Emilia and Romagna (Bologna), and C) in the Romagna coastal area (Ravenna). Vegetation analyses show both qualitative and quantitative differences among the three areas: the greatest variety in vegetation types and habitats is observed in areas A and B (6-7 different vegetation types), while area C appears to be more monotonous (with a mere 3 types). The results of floristic analyses suggest that the abundance of species (based on the number of species observed in 30 phytosociological relevés for each area), depends to a greater extent on micro-environmental factors and site management than on the territorial context: areas A and B, characterised by a fair variety of habitats, display a wider floristic diversity (approx. 180 species from over 50 families) than area C (approx. 120 species from 32 families). The flora is composed mainly of synanthropic species, with high percentages of annual plants (between 30% and 45%) and sub cosmopolitan plants; however, it is also worth noting the presence of several nemoral and hydrophilic species, hidden away in hedges and along ditches, as well as rare plants (about 10% of the total). Phenological patterns show relationships with the life forms and the synecological features of the plants. The analyses of symphenograms show generally bimodal trends of blooming intensity (varying with coenosis, site and year): the first peak corresponds mostly to the onset of anthesis in woody species and annual grasses, while the second one, taking place between late spring and summer, is due to the perennial grasses. The relationships between plants and animals were also investigated, in collaboration with several experts. Significant correlations were observed between certain parameters of Lepidoptera (number of species and abundance) and the plant diversity, as well as the abundance of the grass layer (Puppi et al. 2008). Summing up, in order to preserve and increase biodiversity in the agricultural ecosystems, we have to maintain a network of sub-natural and semi-natural structures. Moreover, these should have a high variety of structural as well as ecological features.