1,721,064 research outputs found
Notula 1481. Soldanella calabrella (Kress) Primulaceae. Notulae alla checklist della flora vascolare italiana.
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Testing indicators of sustainable forest management on understorey composition and diversity in southern Italy through variation partitioning
No full textTree 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. © 2010 Springer Science+Business Media B.V
Plant species diversity in Mediterranean old-growth forests: a case study from central Italy
No full textTo 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,Ellenberg's indicator values and taxonomic distinctness; next,we calculated four different pairwise plot-to-plot dissimilarity matrices based on species composition,functional traits,Ellenberg's 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,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
Multiscale heterogeneity of topsoil properties in southern European old-growth forests
No full textAssessing the contribution of forest soils to carbon (C) and nutrient dynamics is extremely complex due to the high spatial variability of soil properties, at fine to very broad scales. Improving our understanding of soil variability is necessary to scale up sample-based inventory data for the estimation of regional contribution of forest soils to C dynamics. We analyzed the topsoil spatial variability of organic carbon (OC) and matter (OM), nitrogen (N), C/N ratio, texture, and pH in 11 southern European old-growth beech stands. Our aim was to assess the within- and among-stand topsoil variability, and to determine the drivers underlying this variation. For each stand, we sampled the topsoil in 25 quadrats in a 1-ha regular grid where we recorded overstorey structural and compositional attributes, deadwood quantity and quality, microtopography and site conditions. Soil parameters varied highly at both scales: When considering all the topsoil properties together through multivariate analysis, most of the variability occurred at the within-stand scale (mostly due to shifts in organic matter content, C/N, and litter depth); the opposite was true when considering soil properties singularly, with pH, soil texture, and N concentration varying greatly among stands. Most of the among-stand variability depended on climate and on the direct and indirect effects of parent material. Fine-scale variation, instead, depended mainly on overstorey composition and microtopographical variation. Surprisingly, we found no direct influence of overstorey structure on topsoil parameters, likely because soil parameters respond to changes in stand structural features only after a substantial time lag
Drivers of herb-layer species diversity in two unmanaged temperate forests in northern Spain
No full textThe identification of the drivers of diversity in understorey plant assemblages is a major challenge in forest ecology. However, it is not yet fully understood whether the same factors consistently affect different facets of species organization, such as species richness, composition and turnover. Here, we compare the influence of fine-scale environmental variables and spatial organization on the herb-layer flora of two unmanaged and ecologically different forest stands in the Muniellos Biosphere Reserve, Northern Spain. The aims of our study are to identify the most important factors influencing different facets of herb-layer plant organization, and to test whether the effect of such drivers is consistent across facets and forest types. We used Generalized Linear Models, Redundancy Analysis and Multiple Regression on Distance Matrices to model, respectively, the response of species richness, species composition and species turnover to spatial distances as well as to several environmental factors, including forest structure, light conditions, soil and topographical features. We observed a substantial consistency among variables affecting the different facets of ground-layer species organization within stands, with a subset of topographical variables with a transversal effect across facets. Although potential solar radiation was the main variable influencing species richness in the two stands, the factors shaping species composition and turnover varied across forest types: in the beech stand, slope and canopy openness were the main determinants of herb-layer species diversity and turnover; in the oak stand, the main drivers of species composition were related to topography and spatial structure, while spatial distance was the main driver of species turnover. Our study shows that the ecological processes driving fine-scale variation of ground-layer plant richness and composition are similar to those driving species turnover. Although the ecological factors shaping different facets may be the same, we highlight that, at least in temperate forests, these factors are system-specific and vary according to forest types
Commonality and variability in the structural attributes of moist temperate old-growth forests: A global review
No full textTemperate forests have been fundamentally altered by land use and other stressors globally; these have reduced the abundance of primary and old-growth forests in particular. Despite many regional studies, the literature lacks a global synthesis of temperate old-growth structural characteristics. In this study we compare literature derived data on mature and old-growth moist temperate forests with the aim of: (i) exploring global commonalities; (ii) investigating sources of variability among systems; and (iii) highlighting data gaps and research needs. We compiled a dataset of 147 records from 93 papers, and analyzed a set of structural indicators: basal area, stem density, large living trees, live aboveground biomass, quadratic mean diameter, and coarse woody debris volume. These indicators were contrasted between mature and old-growth age classes at a global level and across continents and broad forest types, testing for significance through Monte-Carlo permutation procedure. We also related structural indicators to age, climatic and geographical descriptors. Our results suggest that all structural indicators vary across systems in relation to geographical, compositional, and climatic influences. However old-growth forests showed global commonalities in structure when compared to mature forests: significantly higher densities of large living trees, higher quadratic mean diameter, and higher amounts of live aboveground biomass and coarse woody debris. Furthermore we found inconsistency in the structural variables reported by different papers; lack of studies on temperate forests in Russia, and Western and Central Asia. The findings improve our understanding of old-growth structure and function, and will help inform sustainable forest management and conservation approaches world-wide. © 2012 Elsevier B.V
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