Sabina Burrascano

Multi-taxon and forest structure sampling for identification of indicators and monitoring of old-growth forest

Abstract The most commonly used old‐growth forest indicators are structural attributes; nevertheless, they do not necessarily represent the biodiversity value of old‐growth forests. The aim of this study is to analyse the relationships between species richness data of different taxa and structural indicators of old‐growth and to identify taxonomic/functional groups, species and structural attributes that may be used as indicators of old‐growth. To achieve this goal we sampled forest structure, vascular plants, lichens, bryophytes, fungi, saproxylic beetles and birds in mature and old‐growth stands in southern Italy. We calculated Spearman’s correlation coefficients between species richness data and structural attributes. Analyses of indicator species, co‐occurrences and two‐way clusters were performed on the multi‐taxonomic list. The group of vascular plants most significantly correlated with other groups in terms of species richness; furthermore, it displays the highest proportion of between‐group co‐occurrences. The resulting multi‐taxonomic list of potential indicators may serve as an effective means of detecting and monitoring forest ecosystems; however, for this goal, structure‐based indicators, such as forest structural attributes and vascular plant species composition, are of primary importance.

Old-growth forest structure and deadwood: Are they indicators of plant species composition? A case study from central Italy

Abstract The aim of this paper is to investigate differences in plant species composition between managed and unmanaged forests, and to assess if these difference give rise to a higher plant diversity in the unmanaged forest. Furthermore our aim is to relate forest structure to differences in plant species composition, identifying the structural attributes more strongly related to the unmanaged forest vegetation. We compared an old-growth forest and a managed highforest in the Abruzzo Lazio and Molise National Park (Central Italy). Plant species composition and diversity, deadwood components and live structure have been analyzed. We used permutational multivariate analysis of variance to test the response of species composition to management factor; furthermore, we compared species richness and beta diversity. Redundancy analysis has been used to relate plant species abundances to structural variables; the importance of dead and living wood components has been compared through variation partitioning. Plant species composition proved to be significantly different in the two sites, and the old-growth stand showed a higher plant diversity. From a structural point of view, we found differences especially in the amount and quality of deadwood, and in the diameter class distribution. These variables are also the most important in determining the old-growth stand plant species composition according to redundancy analysis. Variation partitioning confirmed the greater importance of the deadwood variables. Our results suggest that including deadwood surveys in traditional forest inventories could help in finding forests with both structural and floristic old-growth properties to be considered in conservation programmes. The imitation of natural dynamics, through the creation of gaps avoiding deadwood removal, could be an effective strategy for restoring old-growth conditions, also in terms of plant diversity.

Plant species diversity in Mediterranean old-growth forests: A case study from central Italy

Abstract To investigate the differences in understorey composition and diversity between old-growth and managed forests, we analyzed an old-growth and a managed beech stand in the same area displaying similar abiotic features. We considered variations in understorey species composition and richness. The sampled understorey species were characterized in terms of functional traits, Ellenbergs indicator values and taxonomic distinctness; next, we calculated four different pairwise plot-to-plot dissimilarity matrices based on species composition, functional traits, Ellenbergs indices and taxonomic distances. We applied a permutational multivariate extension of ANOVA to test whether the forest stands significantly differ in the considered features. Indicator values of all plant species in managed and old-growth stands were evaluated. The old-growth forest had a higher species richness; permutational analysis of variance showed significant differences between the two stands in plant species composition, functional traits, Ellenberg indices and taxonomic distances. Indicator species analysis highlighted 14 indicator species for the unmanaged stand, while only 3 indicators were found for the managed one. The results suggest that forest management determines ecological differences that strongly affect plant species composition. The knowledge of natural stands dynamics could allow development of new approaches and practices in forest management focusing on biodiversity conservation.

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.

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.

Testing indicators of sustainable forest management on understorey composition and diversity in southern Italy through variation partitioning

Tree species composition and stand structural complexity are valuable indicators of sustainable forest management. This article aims to investigate the relative influence of forest overstorey composition and structural attributes on understorey composition and diversity, taking into account also site characteristics and broad-scale environmental variables. We sampled vascular plant species composition and forest structure in 132 plots in the Cilento and Vallo di Diano National Park (southern Italy). Spearman’s non-parametric correlation coefficients were calculated between overstorey and understorey diversity indices, beech percentage, and altitude and environmental indices. A complete partitioning of the variation in understorey composition was then performed through canonical correspondence analysis considering four sets of variables: (1) overstorey composition, (2) structural attributes, (3) topography, and (4) landscape abiotic variables. Finally, we constructed a regression tree analysis of understorey species richness using the same explanatory variables. Understorey diversity indices were positively correlated with overstorey diversity indices and with environmental indices (i.e., light and soil heterogeneity). Overstorey and understorey diversity indices were negatively correlated with both altitude and the dominance of beech in the overstorey. Compositional variation was due primarily to overstorey composition and secondarily to structural attributes. Regression tree analysis revealed that altitude, overstorey species richness, and structural attributes play an important role in determining understorey species richness. According to our results, understorey composition and diversity are strongly related to overstorey composition and structural attributes. Indeed, the latter proved to be effective indicators of understorey characteristics in the study area.

Ground Layer Plant Species Turnover and Beta Diversity in Southern-European Old-Growth Forests

Different assembly processes may simultaneously affect local-scale variation of species composition in temperate old-growth forests. Ground layer species diversity reflects chance colonization and persistence of low-dispersal species, as well as fine-scale environmental heterogeneity. The latter depends on both purely abiotic factors, such as soil properties and topography, and factors primarily determined by overstorey structure, such as light availability. Understanding the degree to which plant diversity in old-growth forests is associated with structural heterogeneity and/or to dispersal limitation will help assessing the effectiveness of silvicultural practices that recreate old-growth patterns and structures for the conservation or restoration of plant diversity. We used a nested sampling design to assess fine-scale species turnover, i.e. the proportion of species composition that changes among sampling units, across 11 beech-dominated old-growth forests in Southern Europe. For each stand, we also measured a wide range of environmental and structural variables that might explain ground layer species turnover. Our aim was to quantify the relative importance of dispersal limitation in comparison to that of stand structural heterogeneity while controlling for other sources of environmental heterogeneity. For this purpose, we used multiple regression on distance matrices at the within-stand extent, and mixed effect models at the extent of the whole dataset. Species turnover was best predicted by structural and environmental heterogeneity, especially by differences in light availability and in topsoil nutrient concentration and texture. Spatial distances were significant only in four out of eleven stands with a relatively low explanatory power. This suggests that structural heterogeneity is a more important driver of local-scale ground layer species turnover than dispersal limitation in southern European old-growth beech forests.

Submediterranean dry grasslands along the Tyrrhenian sector of central Italy: Synecology, syndynamics and syntaxonomy

Abstract Semi-natural dry grasslands are habitats of high conservation concern. These ecosystems have not been extensively explored in the Tyrrhenian sector of the Italian peninsula, particularly in the Submediterranean climatic region. In order to address this issue and to define the synecology, syndynamics and syntaxonomy of calcareous grasslands in this area, we considered 127 phytosociological relevés. Our sampling was performed in the Lazio region according to a stratified sampling scheme based on homogeneous land units, defined by means of an ecological land classification process. We analyzed the vegetation data using multivariate methods. Two new associations, whose typical aspects occur in the mesotemperate phytoclimatic belt, were identified:Erysimo pseudorhaetici-Dasypyretum villosi (Taenianthero-Aegilopion) and Scorpiuro muricati-Brometum erecti (Phleo-Bromion). Phytoclimatic belts within the Submediterranean region cause a significant degree of differentiation within Scorpiuro-Brometum, which was described at the subassociation and variant levels. The overall relevance of therophytes represents the most important feature distinguishing Scorpiuro-Brometum from the published Bromus erectus associations. At a finer scale, the presence of the two physiognomically different grassland communities is related to different soil types. All these communities are dynamically linked to Quercus virgiliana and Q. pubescens woods, and contribute to the coenological differentiation of the vegetation series related to such woodlands.

Cynosurion cristati grasslands in the central Apennines (Tyrrhenian sector): A phytosociological survey in the Lepini and Prenestini mountains

Abstract Cynosurion cristati grasslands are semi‐natural habitats that have developed on mesotrophic soils with a good water supply and are found from the basal up to the mountain vegetation belts. Differences between the various communities of these grasslands in the European continent have not been fully investigated; in Italy, there is a lack of knowledge of the mesophilous pastures in the central and southern Apennines. In order to shed light on the Cynosurion hay meadows and grasslands in the central Apennines, we considered phytosociological data from the Lepini and Prenestini mountains (central Italy, Tyrrhenian sector): 58 original relevés and a synoptic table containing similar associations throughout the Italian peninsula were analysed using multivariate methods (hierarchical classifications and principal coordinates analysis). Two new associations were distinguished: Hordeum bulbosum meadows, grazed after being mown (Trifolio molinerii–Hordeetum bulbosi), and heavily grazed, unmown pastures with several thorny species (Centaureo calcitrapae–Lolietum perennis). Both these associations have been assigned to Cynosurion cristati, though they differ from the European coenoses owing to the presence of Festuco‐Brometea and Helianthemetea guttati species. Further investigations are warranted to clarify the overall syntaxonomical position of the Italian coenoses in relation to the ecological and phytogeographic variations of Cynosurion, which are considered to be related to traditional land use in mountain agricultural systems. Hay meadows, which are important elements of landscape and biodiversity conservation, particularly feel the negative effects of land abandonment and land use change.

Re-visiting historical semi-natural grasslands in the Apennines to assess patterns of changes in species composition and functional traits

Questions To what extent have semi-natural grassland plant species composition and functional traits changed during the past five decades? Which are the main directions of change? Which environmental, management, and landscape factors have determined these changes? Location Central and southern Apennines of Italy. Methods In 2013-2014, we used a stratified random sampling design to revisit 132 semi-natural grasslands originally sampled between 1966 and 1992. The exact locations of the historical plots were not available but they were associated with detailed vegetation maps. Plots were divided in 17 groups based on study area and original community type. To assess changes in species composition we ran permutational multivariate analysis of variance and redundancy analysis. The extent of change was estimated by comparing each new plot with the quantitative species pool of the corresponding historical group; species composition changes were calculated using Bray-Curtis coefficient, and shifts in functional traits were quantified as differences in community weighted means. These measures of change were used as response variables in mixed effects models including climate, topography, management and landscape metrics as explanatory variables. Results The greatest changes were related to successional dynamics, which occurred mainly in grasslands developing at low altitude and in flattest sites where the soil organic horizon was relatively thick. Colonization by shrubs and trees was facilitated by high soil pH and amount of adjacent forests. Also management factors affected the patterns of shifts in species composition and functional traits: grazing intensity was negatively related to the degree of compositional change as well as to the abundance of woody species, whereas the increase of species associated with frequent grazing disturbance was found at sites with higher values of soil salinity. Conclusions Apennine semi-natural grasslands have undergone substantial changes in species composition and functional traits during recent decades. Compositional changes mainly indicated successional dynamics likely following a decrease in grazing intensity, whereas some more accessible grasslands experienced an increase in disturbance-tolerant species. The combination of the re-visitation approach with functional traits allowed to clarify different directions of changes in species composition adding information on the ecological processes related to these changes. This article is protected by copyright. All rights reserved.