Drivers of distance‐decay in bryophyte assemblages at multiple spatial scales: Dispersal limitations or environmental control?

Questions: Despite the increasing scientific interest in distance decay of compositional similarity in ecology, the scale dependence of geographical versus environmental control on distance decay of biological communities has not been properly addressed so far. The present work highlights the relative importance of niche-based processes versus dispersal limitations on distance decay patterns of epilithic bryophyte assemblages at different spatial scales. Location: Serra de Sintra, central Portugal. Methods: We adopted a nested sampling design with 32 selected sampling sites in each of which two clusters, each with five rocks, were surveyed. Each cluster was characterized by a set of 15 macroscale variables, which were divided into environmental and anthropogenic. For each rock eight microscale variables were recorded. Partial Mantel tests were used to assess the relative importance of geographical and environmental distance on community dissimilarity for each grain size (site, cluster, rock). Quantile regressions were used to describe the decay patterns of community similarity with respect to geographical and environmental distances. Ordination analyses and variation partitioning techniques were applied to assess the pure and shared effects of measured variables on bryophyte community composition. Results: Environmental distance based upon macroscale predictors was significantly correlated to community similarity, while no significant correlation was found for ecological distance calculated for microscale predictors, except at the largest grain size. The decrease of community similarity with geographical and environmental distance was thus consistently strengthened with increasing sample grain. Compositional variation was best explained by anthropogenic variables. Conclusions: The relative importance of environmental versus geographical distance on compositional similarity in epilithic bryophyte communities varies with the spatial scale of the predictors and with the sample grain. The decrease of similarity with increasing distance is related to changes in habitat features, especially those driven by human disturbance, while it is weakly affected by variations in substrate features.info:eu-repo/semantics/publishedVersio

Diversity, distributional patterns and distance decay in epilythic bryophyte assemblages in forest habitats

Bryophytes represent a fundamental component of diversity in forest ecosystems. They provide crucial information about the state of the habitat not only by their taxonomical diversification, but also by the variety of life forms and life strategies they adopt to maximize water retention and spore dispersal. However, most of the studies dealing with bryophyte ecology and functional role in forest habitats have focused on epiphytic and epigeous communities, which constitute their more representative component, neglecting the epilythic ones. In this study we thus examined how environmental and anthropogenic drivers shape distributional patterns of epilythic bryophytes and affect their diversity, as assessed by a set of different indicators describing, among other things, the variety of their life forms, life strategies and chorological types. We also investigated distance decay patterns, as a first step for testing at which spatial scale environmental and anthropogenic drivers affect beta diversity more significantly. Species turnover was estimated at different levels, as a nested design was adopted for sampling. Overall, 64 surveys on epilythic bryophyte vegetation were carried out at 32 sampling locations scattered throughout the Serra de Sintra massif, in central Portugal, on a total of 320 boulders sampled and 1600 plots. Regression analysis and gradient analyses of environmental and anthropogenic descriptors on diversity indicators and distribution patterns, respectively, were performed. In order to discriminate the effect of environmental drivers at different grains, two different sets of descriptors, one to be tested at sample level, the other one at substrate level, were selected. For distance decay, all the spatial levels were considered and compositional as well as spatial distances were aggregated through the various levels. From the results it emerges that for epilythic bryophytes such factors as thickness of the canopy cover and diversification of micro-habitats represent the crucial drivers. As for anthropogenic drivers, while alteration of the habitat structure and physical pressure on it severely decrease biodiversity, creation of artificial habitats characterized by abundance of species from different bio-geographical regions and constant supply of water appears to significantly enhance it. Besides, from the analysis of distance decay patterns it emerges that the trend already described in literature for vascular plants holds for bryophytes as well the dissimilarity of species composition increasing as geographic distance increases

An overview of the Italian forest biodiversity and its conservation level, based on the first outcomes of the 4th Habitat Report ex-Art. 17

In 2019 the 4th Report ex-Art. 17 on the conservation status (CS) of Annex I Habitats of the 92/43/EEC Directive was expected by every EU/28 country, with reference to the period 2013-18. In Italy, the process was in charge to the Italian Institute for Environmental Protection and Research (ISPRA), on behalf of the Ministry for Environment, Land and Sea Protection (MATTM), with the scientific support of the Italian Botanical Society (SBI). A large group of thematic and territorial experts elaborated the available data concerning the 124 types of terrestrial and inland water Habitats present in Italy, 39 of which are represented by Forest Habitats (Group 9),. The main aim of the work was the evaluation of the overall CS of each Habitat by Biogeographic Region (Mediterranean, Continental and Alpine), for a total amount of 294 assessments. A high proportion of these (92, corresponding to 31% of the total) referred to Forest Habitats, including 20 marginal types for which the CS was not requested. The analysis was carried out at different scales: a) administrative territory, through the data contained in the ISPRA database, whose compilation was in charge to the Regions and Autonomous Provinces; b) Natura 2000 site, with the latest updates available (Standard Data Forms updated to 2018); c) national scale, implementing the distribution maps for each Habitat based on the European grid ETRS89-LAEA5210 (10x10 km2 mesh); d) Biogeographic Region, scale of the final assessment. Cartographic outcomes, associated databases and additional data used for the assessments will be available online on the ISPRA Portal as soon as the validation process by the European Commission will be completed. A dedicated archive named "HAB_IT" has been created in the national database "VegItaly" (1), managed by the Italian Society of Vegetation Science, where the phytosociological relevés representative of the various Annex I Habitats in Italy will be archived and freely accessible. An overview of the results regarding the Forest habitats is here provided, including a comparison with the outcomes of the former reporting cycle, the 3rd Report ex-Art. 17 (2). In several cases (e.g. 9120, 91L0), the distribution maps have been remarkably improved due to better knowledge and more fitful interpretation. The conservation status resulted as Favourable (FV) for 6,7%, Inadequate (U1) for 58,7% and Bad (U1) for 32,0% of the 72 assessed forest Habitat types. In no case there was an improvement of the conservation status, while in 6 cases a worsening of the conditions resulted from the data analysis, pointing out the Habitats types with a higher need of action. Similarly to other projects carried out as a team by the network of Annex I Habitat experts of the Italian Botanical Society and the Italian Society for Vegetation Science (e.g. 3, 4), this is another step in the direction of supporting the implementation of the 92/43/EEC "Habitat" Directive in Italy and Europe. On this ground, the high biodiversity of the Italian forest Habitats could be emphasized, however results pointed out that some rare or endemic types (e.g. Alnus cordata or Betula aetnensis-dominated forests) are still scarcely acknowledged by the most prominent EU conservation tools such as the Annex I to the "Habitat" Directive. 1) F. Landucci et al. (2012) Plant Biosyst., 146(4), 756-763 2) P. Genovesi et al. (2014) ISPRA, Serie Rapporti, 194/2014 3) E. Biondi et al. (2009) Società Botanica Italiana, MATTM, D.P.N., http://vnr.unipg.it/habitat/ 4) D. Gigante et al. (2016) Plant Sociology, 53(2), 77-8

Hans Hürlimann (1921-2014)

Hans Hürlimann, Swiss botanist and leading specialist on the liverwort flora of the South Pacific region, died on 1 October 2014 in Basel at the age of 93. Born in Brugg (Kanton Aargau), Hans went to school in Winterthur and studied biology at the University of Zürich, where he obtained his doctorate in 1950 on a prize-winning study dealing with the life history and ecology of the common reed. Following his promotion, he left to the South Pacific to join the Second Swiss Botanical Expedition to New Caledonia. During two years, from 1950-1952, he made large collections of bryophytes and flowering plants (the latter together with his field companions Marcel Baumann-Bodenheim from Zürich and André Guillaumin from Paris), mainly on New Caledonia, but also on Tahiti, Fiji and Tonga. The identification of the specimens and publication of the results would occupy him for the rest of his life.</p

Drivers of distance-decay in bryophyte assemblages at multiple spatial scales: dispersal limitations or environmental control?

Abstract Questions: Despite the increasing scientific interest in distance decay of compositional similarity in ecology, the scale-dependence of geographical vs environmental control on distance decay of biological communities has not been properly addressed so far. The present work highlights the relative importance of niche-based processes vs dispersal limitations on distance decay patterns of epilithic bryophyte assemblages at different spatial scales. Location: Serra de Sintra, central Portugal. Methods: We adopted a nested sampling design with 32 selected sampling sites in each of which two clusters, each with five rocks, were surveyed. Each cluster was characterized by a set of 15 macro-scale variables, which were divided into environmental and anthropogenic. For each rock eight micro-scale variables were recorded. Partial Mantel tests were used to assess the relative importance of geographical and environmental distance on community dissimilarity for each grain size (site, cluster, rock). Quantile regressions were used to describe the decay patterns of community similarity with respect to geographical and environmental distances. Ordination analyses and variation partitioning techniques were applied to assess the pure and shared effects of measured variables on bryophyte community composition. Results: Environmental distance based upon macro-scale predictors was significantly correlated to community similarity, while no significant correlation was found for ecological distance calculated for micro-scale predictors, except at the largest grain size. The decrease of community similarity with geographical and environmental distance was thus consistently strengthened with increasing sample grain. Compositional variation was best explained by anthropogenic variables. Conclusions: The relative importance of environmental vs geographical distance on compositional similarity in epilithic bryophyte communities varies with the spatial scale of the predictors and with the sample grain. The decrease of similarity with increasing distance is related to changes in habitat features, especially those driven by human disturbance, while is weakly affected by variations in substrate features

Litter decomposition: effects of temperature driven by soil moisture and vegetation type

Aims We examined the importance of litter quality and microclimate on early-stage litter mass loss, analysed the importance of interactions among environmental factors in determining key decomposition parameters and compared the variation in decomposition rates in vegetation types and sites with similar climate. Methods Following the Tea-Bag Index approach, 464 tea-bags were incubated in the soil in 79 sites, distributed across Italy, which included six vegetation types and a broad range of microclimatic conditions. Results Litter type exerted a stronger control on mass loss compared to climatic factors. The effects of soil moisture were not the same for high and lower quality litter. In addition, the effects of temperature on the decomposition rate depended on soil moisture. The stabilization factor was strongly temperature-dependent, but the influence of temperature differed among vegetation types: those dominated by small-size plants showed a strong decrease in the potential amount of plant material entering into the soil stock under warmer temperatures. The lowest variation in decomposition rate was found in sites characterised by low temperatures, and, among the vegetation types, in alpine snowbeds. Conclusions The role of litter quality and of the interactions among environmental conditions can potentially determine significant shifts in the expected patterns of ecosystem carbon fluxes