Michela Marignani

Lichens and bryophytes as indicators of old‐growth features in Mediterranean forests

Abstract This study is focused on the selection of variables affecting lichen and bryophyte diversity in Mediterranean deciduous forests. Plots representing two forest types (Fagus sylvatica and Quercus cerris forests) and two forest continuity categories (old‐growth (OG) and non‐OG forests) were selected in the Cilento and Vallo di Diano National Park (Italy). The presence and the abundance of bryophytes and epiphytic lichens were recorded. Structural variables of the forests and vascular plant species richness have been used as predictors. A strong positive correspondence between the two groups of organisms was found. Higher species richness and the distribution of rare species are related to OG stands, while a qualitative (species composition) rather than a quantitative (species richness) difference between the two forest types was observed. Some species elsewhere considered as indicators of forest continuity, such as Lobaria pulmonaria, Antitrichia curtipendula, and Homalothecium sericeum, are associated with OG forests, independently from forest type, suggesting that they can be regarded as suitable indicators also in Mediterranean forests. Finally, our results suggest that old trees, high levels of basal area, a broad range of diameter classes, and high understory diversity are the main structural features affecting cryptogamic communities, while no correlation was found with the occurrence of deadwood.

The concept of land ecological network and its design using a land unit approach

Abstract The introduction of ecological networks into nature conservation policies promotes a new planning model for maintaining biological and landscape diversity and assisting policy sectors in the conservation of natural ecosystems. We propose a method to design an ecological network of sites that satisfy the main ecological needs of species, community and ecosystems by analysing the pattern of natural elements in the land mosaic. We define the concept of land ecological network (LEN) and design the LEN in the province of Rome (Lazio, Italy) on a local scale (1:50,000). The LEN is composed of core areas, buffer zones and landscape connections each of which has its own management regime. This work was carried out as part of the province of Rome planning scheme, which represents a prescriptive document of General Provincial Territorial Plan of Rome. The LEN integrates ecological data with a hierarchical land classification and provides a scientifically sound basis for conservation strategies at different scales.

Computing diversity from dated phylogenies and taxonomic hierarchies: does it make a difference to the conclusions?

Recently, dated phylogenies have been increasingly used for ecological studies on community structure and conservation planning. There is, however, a major impediment to a systematic application of phylogenetic methods in ecology: reliable phylogenies with time-calibrated branch lengths are lacking for a large number of taxonomic groups and this condition is likely to continue for a long time. A solution for this problem consists in using undated phylogenies or taxonomic hierarchies as proxies for dated phylogenies. Nonetheless, little is known on the potential loss of information of these approaches compared to studies using dated phylogenies with time-calibrated branch lengths. The aim of this study is to ask how the use of undated phylogenies and taxonomic hierarchies biases a very simple measure of diversity, the mean pairwise phylogenetic distance between community species, compared to the diversity of dated phylogenies derived from the freely available software Phylomatic. This is illustrated with three sets of data on plant species sampled at different scales. Our results show that: (1) surprisingly, the diversity computed from dated phylogenies derived from Phylomatic is more strongly related to the diversity computed from taxonomic hierarchies than to the diversity computed from undated phylogenies, while (2) less surprisingly, the strength of this relationship increases if we consider only angiosperm species.

Do National Parks play an active role in conserving the natural capital of Italy

Abstract The aims of this paper are to describe the state of the environmental knowledge of the terrestrial National Parks (NPs) in Italy and to assess their conservation status and their efficacy to deal with the pressures of land changes. We collected and analysed data regarding land units, vegetation series, old-growth forests, Important Plant Areas (IPAs) and changes in landscape conservation status, to provide a systemic overview of the condition of the NPs and to verify their effectiveness against pressures and impacts induced by human activities. Moreover, NPs were organised according to the ecoregional setting for a multi-scale interpretation of biodiversity baselines and indicators. The results highlight the essential role of NP system for biodiversity conservation in Italy. The long-term protection regime proved to be particularly effective as a means of conserving ageing forest communities, threatened vascular plants and contrasting threats posed by human-induced changes. However, this work points out the need for more detailed scientific data for a comprehensive assessment of the representativeness and effectiveness of the NP system.

Are Cichorieae an indicator of open habitats and pastoralism in current and past vegetation studies

Cichorieae, one of the six tribes of the sub-family Cichorioideae (Asteraceae), produces a well-recognisable fenestrate pollen type. In the Mediterranean area, the significance of high percentages of Cichorieae pollen from archaeological layers is still questioned. We assessed the presence of Cichorieae as indicators of open habitats and pasturelands in current plant communities by comparing data on vegetation composition with pollen spectra from two Hellenistic sites of Basilicata (southern Italy): Difesa San Biagio in the low valley of the river Bradano and Torre di Satriano in the Lucanian Apennines. We also analysed the pollen morphology bringing to the discrimination of size classes within the fenestrate type of Cichorieae. Pollen spectra from the considered archaeological sites have low forest cover (7% on average); Asteraceae and Poaceae are prevalent; Cichorieae account to ca. 23%; coprophilous fungal spores are varied and present high concentrations. In surface soil samples collected near the sites, Cichorieae pollen is about 12%. In current vegetation types, an increasing abundance of Cichorieae was observed from salt marshes, forests and shrublands to open habitats and grasslands. This is coherent with the actual land cover around the study sites and the findings of the archaeological sample that point to an open landscape dominated by pastures and cultivated fields. Our integrated approach confirmed that today Cichorieae are common in secondary pastures and in some types of primary open habitats of southern Italy: hence, high percentages of this pollen can be considered a good indicator of these habitats even in past environment reconstructions.

The role of regional and local scale predictors for plant species richness in Mediterranean forests

Abstract Both local and regional predictors play a role in determining plant community structure and composition. Climate, soil features as well as different local history and management affect forest understorey and tree species composition, but to date their specific role is relatively unknown. Few studies have addressed the importance of these predictors, especially in the Mediterranean area, where environmental conditions and human impacts have generated heterogeneous forest communities. In this study, the relationships between environmental variables and species richness of different groups of vascular plants (vascular species, woody species and open habitat species) and bryophytes were investigated in Tuscan forests. A total of 37 environmental variables were used by generalised linear model fitting in order to find parsimonious sub-sets of environmental factors (predictors) that are able to explain species diversity patterns at the local scale. Moreover, the role of regional and local variable groups on species richness of the considered plant groups was estimated by using the variance partitioning approach. We found that local variables, such as forest management and structure, explained more variance than regional variables for total species richness, open habitat species richness and bryophyte species richness. On the other hand, regional variables (such as elevation) played a central role for woody species richness.

Effects of fragmentation on vascular plant diversity in a Mediterranean forest archipelago

Abstract We analysed the effects of patch size and isolation on vascular plants in Quercus cerris forest surrounding Rome (Italy). We randomly sampled 96 plots within 18 forest patches with homogeneous environmental variables; the patches ranged from 1.4 ha to 424.5 ha and were divided into four size classes. We performed the analyses at the patch level using linear regression. At the size class level, the analysis of species richness response to fragmentation (area effect) was performed with ANOVA, while the effect on community composition was analysed by means of PERMANOVA. We also investigated which species could be used as indicator species for each size class. Lastly, to evaluate the advantages of conserving several small patches as opposed to few large ones, we used a cumulative area approach ranking forest fragments. The correlation between species richness and patch area was positive, with a significant difference between the “large” and “small” size classes, while analysis on community composition showed that “large” versus “medium” and “large” versus “small” were significantly different. Nemoral species were recognised as indicators in the “large” class, and shrub and edge species in the “small” class. Our results indicate that 10 ha may be a suitable forest size threshold for planning and conservation.

Natural and human impact in Mediterranean landscapes: An intriguing puzzle or only a question of time?

Abstract Time is a key factor to understand the effects of disturbance on natural communities or ecosystems. In Mediterranean landscapes, where nature and humans have been strongly intermingling since mid-Holocene, the relationships between plant ecology and palaeoecology and their role for the interpretation of natural and anthropogenic changes still needs to be clearly understood. Ecology and palaeoecology are both investigating such problems, but each of them cannot disentangle the specific role played by nature and by humans in shaping the present plant communities and landscapes. A new age of cooperation among researchers in ecology and palaeoecology is needed, and the integration of these closely related but separated research fields is necessary to explain the resulting dynamic puzzle. Plant ecologists should avoid the oversimplification of the actual causes as the exclusive drivers of plant communities and landscapes and force the exploitation of the available data to generate and test new hypotheses for past, present and future environmental reconstructions and management. Even when planning for the future biodiversity conservation, we need to properly use the existing information about millennia of human effects on the natural biotas, to properly set landscape management and conservation priorities.

Under the shadow of a big plane tree: Why Platanus orientalis should be considered an archaeophyte in Italy

In Italy, Platanus orientalis L. is judged as an endangered species by some authors and non-native by others: these contrasting assessments can mislead the prioritization of management actions to preserve the species and the riparian vegetation that is its host. Based on a multidisciplinary approach, including palaeobotanical and ecological information, we assessed its status in Italy including the ecological and conservation value of the riparian plant communities hosting it in the Cilento National Park (S-Italy). Palaeobotanical data showed that P. orientalis in Italy should be considered an archaeophyte. According to the ecological assessment of the riparian plant communities hosting P. orientalis, the presence of the species can be interpreted as an indicator of an unfavourable state for the conservation of riparian vegetation. Knowing the status of a species remains one of the first steps to take to correctly propose scientifically based solutions for the conservation of plant diversity. However, there are no absolute criteria for conservation because all conservation objectives can be considered as cultural values. In this context, P. orientalis should be protected as a symbolic tree, an archaeophyte testifying an ancient common Mediterranean cultural heritage, worthy of preservation but outside of natural habitats.

Palaeoecology and long-term human impact in plant biology

Human impact is a collective concept that requires a holistic approach. Human needs eventually caused the development of cultural landscapes that are at the base of the current landscapes. The papers included in this special issue are evidence that cooperation between different disciplines helps to understand the trend of environmental transformation from past to future. Palaeoecology studies ecosystems of the past and needs archaeology to deepen sociocultural intervention in environmental patterns. In a similar way, ecologists have to include the complexity of societies and economies into landscape ecology by adding principles of human ecology into sustainability science. A brief history of previous actions encouraging the integration of palynology, archaeobotany, archaeology, botany and ecology is reported. The application of integrated studies comes to a new point, the research on the Long-Term Human Impact.