B Paura

Structure, ecology and plant richness patterns in fragmented beech forests

Background: Landscape fragmentation constitutes one of the most severe causes of global biodiversity loss. Aims: We studied Fagus sylvatica forests with different levels of fragmentation to address the following question: do fragmented and non-fragmented forests present a similar floristic composition and richness, structural parameters and ecological features? Methods: Vascular plant species were randomly sampled based on a beech forest map classified into three fragmentation levels. We compared overall native and diagnostic species richness patterns of the different fragmentation levels using rarefaction curves and the ratio between diagnostic and all species curves. We also contrasted different fragmentation levels of beech forests, focusing on floristic information, structural parameters, standard ecological features and the distribution of edge and clearing species. Results: Rarefaction analysis showed two opposite trends: the diversity of diagnostic species decreased in fragmented forests as the overall diversity increased. In highly fragmented forests, we found significantly higher values for therophyte and phanerophyte frequencies, light Ellenberg indicator values and edge and clearing species diversity. Conclusions: The integration of floristic analysis, particularly of certain diagnostic groups, with structural and ecological studies is more sensitive and significant than species richness alone, and could offer useful information for forest conservation and management.

Downy-Oak Woods of Italy: Phytogeographical Remarks on a Controversial Taxonomic and Ecologic Issue

The importance of downy oak as an integral component of the “submediterranean” woods has been underscored by many studies. Nevertheless, terms like “submediterranean” and “downy oak” are some of the most poorly understood concepts in European phytogeographic and taxonomic research. Downy oak is well known to be a problematic taxon. The name “Quercus pubescens” (= Q. humilis) combines populations characterized by increasing phenotypic and genomic polymorphisms along north-south gradients, which is explained as the result of a “founder effect” produced by a relatively fast post-glacial re-colonization of the northern areas through rare long-distance dispersal events.

Monitoring Natura 2000 habitats: habitat 92A0 in central Italy as an example

The evaluation and the subsequent monitoring of the conservation status of habitats is one of the key steps in nature protection. While some European countries have tested suitable methodologies, others, including Italy, lack procedures tested at the national level. The aim of this work is to propose a method to assess the conservation status of habitat 92A0 (Salix alba and Populus alba galleries) in central Italy, and to test the method using data from the Molise region. We selected parameters that highlight the conservation status of the flora and vegetation in order to assess habitat structures and functions at the site level. After selecting the parameters, we tested them on a training dataset of 22 unpublished phytosociological releves taken from the whole dataset, which consists of 119 releves (49 unpublished releves for the study area, and 70 published releves for central Italy). We detected the most serious conservation problems in the middle and lower course of the Biferno river: the past use of river terraces for agriculture and continual human interventions on the river water flow have drastically reduced the riparian forests of Molise. Our results show that in areas in which forest structure and floristic composition have been substantially modified, certain alien plant species, particularly Robinia pseudoacacia, Amorpha fruticosa and Erigeron canadensis, have spread extensively along rivers. In the management of riparian forests, actions aimed at maintaining the stratification of the forest, its uneven-agedness and tree species richness may help to ensure the conservation status, as well as favour the restoration, of habitat 92A0.

Using vegetation dynamics to face the challenge of the conservation status assessment in semi-natural habitats

The conservation of semi-natural habitats represents a primary challenge for European nature conservation due to their great species diversity and their vulnerability to ongoing massive land-use changes. As these changes rapidly transform and phase out semi-natural habitats, conservation measures should be prompt and specifically focused on a sound assessment of the degree of conservation. Here we develop a methodological strategy for the assessment of the degree of conservation of semi-natural grasslands based on well-defined criteria rather than on expert opinion. Through mixed effect models, we tested ten potential indicators, encompassing proxies of species composition, habitat structure, and landscape patterns, against a measure of compositional change from habitat favourable condition, i.e., an inverse proxy of conservation status. This measure derives from the re-visitation of 132 sampling units historically sampled between 1966 and 1992 along the Apennines. The compositional change was quantified as the dissimilarity between historical habitat species pools and the composition of current communities. The compositional change was significantly related to the number of habitat diagnostic species and the relative cover of woody species with opposite sign (positive and negative, respectively). We classified and combined the classes of these two indicators in each sampling unit to assess the habitat degree of conservation at the plot and at the Natura 2000 site level. At the plot level, our assessment was in good agreement with the occurrence of species of conservation concern. On the other hand, at the site level, our assessment was not always harmonic with the habitat conservation assessment officially reported for the site investigated.