Simona Maccherini

Evaluation and monitoring of the flora in a nature reserve by estimation methods

Abstract We tested the use of non-parametric estimators of species richness to evaluate the flora of a relatively large (431 ha) nature reserve, using a sampling area much lower than that used in previous studies. Different estimation methods were applied to floristic data obtained from 50 random plots: the number of observed species, the extrapolated accumulation curves based on the Michaelis–Menten model and the non-parametric estimators based on incidence data (Chao2, first-order Jackknife, second-order Jackknife and bootstrap). To test the performance of the estimators, five data sets were created on the basis of life-forms. The estimates were compared with reference values obtained by traditional floristic and vegetation sampling. The power of the different estimation methods could not definitively be determined, but the first- and second-order Jackknives seem to be the most precise. Although total species richness was underestimated, the sample-based approach provided accurate information for quantitative comparison of time series of data related to ecological changes, vegetation dynamics and environmental changes. This sample-based data included basic statistics on species richness and species frequency distributions as well as the life-form spectrum, at the plot and the whole site scales.

Effects of nutrient addition on species diversity and ground cover of “serpentine” vegetation

ABSTRACT Two nutrient addition experiments were carried out within a program of vegetation ecology of ultramafic soils in Tuscany, Italy. Nitrogen and especially phosphorus induced a slight increase in plant species richness and a significant increase in ground cover, but their interaction was not significant. The addition of nitrogen, phosphorus and potassium together greatly promoted ground cover and showed a partial effect in promoting species richness. The addition of calcium had the same effect on species richness, but did not affect ground cover or have any synergistic effect with nitrogen, phosphorus and potassium. Species composition was not significantly influenced by any of the treatments and the ground cover increases observed concerned species already growing in the plots. Availability of soil elements differed for calcium and potassium in the plots where they were added. The addition of calcium also reduced the availability of manganese, nickel and magnesium, as well as the Mg/Ca ratio, and i...

Assessment of ectomycorrhizal fungal communities in the natural habitats of Tuber magnatum (Ascomycota, Pezizales)

The ectomycorrhizal (ECM) fungal communities of four natural Tuber magnatum truffle grounds, located in different Italian regions (Abruzzo, Emilia-Romagna, Molise, and Tuscany), were studied. The main objective of this study was to characterize and compare the ECM fungal communities in the different regions and in productive (where T. magnatum ascomata were found) and nonproductive points. More than 8,000 (8,100) colonized root tips were counted in 73 soil cores, and 129 operational taxonomic units were identified using morphological and molecular methods. Although the composition of the ECM fungal communities studied varied, we were able to highlight some common characteristics. The most plentiful ECM fungal taxa belong to the Thelephoraceae and Sebacinaceae families followed by Inocybaceae and Russulaceae. Although several ectomycorrhizas belonging to Tuber genus were identified, no T. magnatum ectomycorrhizas were found. The putative ecological significance of some species is discussed.

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.

Germinable soil seed-bank of former grassland converted to coniferous plantation

The influence of afforestation with cedars on field layer vegetation and on the germinable soil seed-bank were investigated along a 60-m transect merging from open grassland to sparse and dense canopy cover. A total of 132 species were found, 76 in the seed-bank and 109 in the vegetation, with 53 species in common. Conifer cover was not found to be associated with a decrease in total number of species in the vegetation or seed-bank, but the mean number of species in the vegetation, total cover in field layer vegetation and mean number of individuals in the seed-bank decreased significantly from grassland to forest stands. The grassland seed-bank was dominated by Saxifraga tridactylites and Veronica agrestis; the seed-bank of plots of scattered cedars was dominated by Trifolium incarnatum ssp. molinerii; and that of dense cedar plantations was dominated by Campanula rapunculus. The number and cover of grassland species of field layer vegetation decreased in the forest, with respect to open grassland, and the same trend was found for density of individuals in the seed-bank. It is concluded that grassland restoration by cutting cedars cannot rely on the presence of grassland species in the soil seed-bank.

Scale dependence of plant species richness in a network of protected areas

Despite the widely recognised importance of reserve networks, their effectiveness in encompassing and maintaining biodiversity is still debated. Species diversity is one of the most affordable measures of biodiversity, but it is difficult to survey such data over large scales. This research aimed to perform a sample-based assessment of species richness of groups of plants with different conservation value (alien species, protected species, and all species) within a reserve network, testing the use of partitioning as a tool for assessing diversity at different spatial scales, from the plot to the entire network. Plant diversity patterns differed for the groups of species for most of the investigated spatial scales. Despite these patterns assumed divergent tendencies when different species groups were considered, most of the species richness within the network was given by larger scale β-diversity for both alien and protected species, as well for all species. Diversity partitioning proved an effective tool to quantify the role of spatial scales in structuring the total species richness of the network, and is helpful in planning reserve networks.

An evaluation of seed zone delineation using phenotypic and population genomic data on black alder Alnus glutinosa

Summary 1. Delineation of seed zones or provenance regions to preserve local adaptation is a common practice in forestry and restoration, as locally adapted plants generally possess relatively high levels of productivity and resistance. Provenance trials typically quantify the degree of phenotypic divergence among individuals and populations raised under common conditions, which is time-consuming and potentially confounded by phenotypic plasticity and maternal effects. 2. Here, we put forward population genomics, the screening of individual genomes for the genetic signature of adaptation, as a fast and reliable strategy to evaluate seed zone delineation. To illustrate the value of this approach, we quantified the degree of genomic adaptation within and among Belgian black alder Alnus glutinosa provenances and compared results with traditional provenance trials. Distant European reference regions were included to validate the approaches, as larger environmental differences at a European scale are expected to result in larger adaptive responses. 3. Local provenances did not perform better than foreign provenances at the scale of Belgian seed zones, in contrast to the comparisons with the distant European regions. A significant site effect indicated that plastic responses rather than local adaptation explain phenotypic differences among seed zones. The common garden revealed little evidence for adaptation for all measured traits, both among seed zones and among distant regions. 4. The number and strength of genetic outliers was not significantly larger among Belgian seed zones than within these seed zones, but was significantly larger between Belgian seed zones and the distant European reference regions. 5. Synthesis and applications. The lack of adaptive divergence among Belgian seed zones supports an expansion of current provenance regions into larger seed zones. The results also show that population genomics can be an accurate and time-efficient resource to assist decisions on seed sourcing. This highlights the importance of raising awareness of the potential benefits of this novel approach among policy makers, foresters and restoration practitioners.

Relating spectral and species diversity through rarefaction curves

Rarefaction represents a powerful analytical approach in ecology for estimating the expected number of species within a given study area from local (α‐diversity) to regional (γ‐diversity) scales. From a landscape perspective, rarefaction curves are directly related to the environmental heterogeneity of the area sampled. The greater the landscape heterogeneity, the greater the expected species diversity. Therefore, remotely sensed images may potentially be used for predicting species diversity through the indirect method of analysing local spectral variation. The aim of this study was to test whether spectral variability can be used as a proxy for species diversity, from local to regional spatial scales. A total of 977 sampling units, each 50 m×50 m, were selected within the Asciano district (Central Italy) following a stratified random sampling. Each sampling unit was manually classified according to the first level of the Corine Land Cover classification legend. Data on plant species composition were collected in 10 m×10 m plots located within 98 random sampling units. The normalized difference vegetation index (NDVI) was calculated from a QuickBird image, and quantized into 8‐bit data (256 digital numbers, DNs) for building spectral rarefaction curves. Only those plots falling within the QuickBird image were used, which had the effect of reducing the thematic legend to two classes: crops and seminatural vegetation. Species and spectral rarefaction curves were then constructed for each land cover class. Rarefaction curves based on species and spectral properties showed similar results, that is a significantly different number of accumulated values given the same sampling effort for the two classes considered. The results of this study suggest that the shape of the spectral rarefaction curves may be an indirect indicator of environmental diversity, and thus may have potential for predicting biodiversity from local to landscape scales.

Mapping patterns of ferns species richness through the use of herbarium data

This paper aims to analyse the spatial patterns of sampling effort and species richness of pteridophyte in a well-investigated region as Tuscany, Italy, by using data stored from a geodatabase storing information on the specimens preserved in the main herbaria of the region. A total of 6,905 records about pteridophyte specimens were extracted from the geodatabase, and 5,638 of such specimens were studied through the use of spatial statistical techniques. The data about the sampling effort and species richness were analysed in relation to topographical variables to assess any significant relationship. Specimen-based rarefaction techniques were used to compare areas with different number of detected species. The analysis of the sampling effort data showed a nonhomogeneous distribution of herbarium data, with some areas being intensively sampled and others being almost unsampled. Thus, the geographical distribution of specimens was extremely clustered. The comparison across geographical areas through specimen-based rarefaction curves showed great differences in species richness and sampling completeness. The analysis of the residuals of species–area relationships evidenced that the distance to water bodies was the only significant topographical variable in controlling species diversity.

Ambient levels of nitrogen dioxide (NO2) may reduce pollen viability in Austrian pine (Pinus nigra Arnold) trees — Correlative evidence from a field study

A fully randomized sampling design was adopted to test whether pollen viability of Austrian pine (Pinus nigra Arnold) was impacted by NO(2) pollution. Spatial strata (500500 m each) with high (41.9-44.6 microg m(-3)) and low (15.4-21.0 microg m(-3)) NO(2) were selected from a defined population in a small area (236.5 km(2), <200 m range in elevation) in Northern Italy. Pollen viability was measured by means of the Tetrazolium (TTC) test. Analysis of variance by means of a generalised linear model showed that NO(2) was a significant factor (P=0.0425) affecting pollen viability. Within the treatment, no significant differences were detected among replicates. Within each replicate, sampling unit data were significantly different (P=0.000) and this suggested some improvement in the applied sampling design was needed. Pollen viability was significantly related to pollen germination (P<0.01) and tube length (P<0.01). This suggested a possible impact of NO(2) on the regeneration of Austrian pine in polluted environments.