5 research outputs found

    Can β-diversity drive dry pastures conservation priorities?

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    β-diversity is a major determinant of species diversity at the regional scale. Biological, spatial and environmental determinants have been suggested as drivers of composition variation in semi-natural grasslands. The relative importance of such factors is inconsistent among studies also in relation to scale differences. Our aim is to discuss the influence of the scale in determining the relative contribution of spatial and environmental factors to the variation inβ-diversity. We used data on central Italian dry grassland (Habitat 6210) and considered two different extents. We built dissimilarity matrices based on species abundances, metric coordinates and environmental factors. We used the former as response in a Multiple Regression on distance matrices to obtain a partition of the variance between the other factors. Furthermore, we used Multivariate Regression Trees to identify the major environmental determinants of grassland composition. Our results strongly suggest that, to conserve most of the diversity in dry grasslands of the habitat, we should take into account differences in rainfall at the broadest scale, and in soil development at a local scale

    Drivers of beta-diversity variation in Bromus erectus semi-natural dry grasslands

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    Questions What are the main drivers of variation in beta-diversity for Bromus erectus semi-natural dry grasslands of habitat 6210(*) at different scales? How should environmental variables and spatial patterns be taken into account to conserve the maximum possible beta-diversity within the habitat? Location Central Italy. Methods We used 195 vegetation releves distributed in three nested extents: a single mountain, a mountain chain and southern Lazio. Multiple regression on distance matrices was performed using dissimilarity matrices based on: (1) species abundances as response variables; (2) spatial coordinates and environmental parameters (altitude, slope, percentage of rock and stone coverage, aspect, annual rainfall) as explanatory variables. The two groups of explanatory variables were used separately to partition the variation, and jointly to assess the relative contribution of each individual variable. Those variables found to significantly affect beta-diversity were used to: (1) compare beta-diversity levels between a set of randomly selected and a set of stratified releves; and (2) analyse the habitat distribution across environmental gradients. These analyses, together with the curves describing the relationships between spatial distances and composition dissimilarities, were used to inform management decisions for the habitat. Results Most of the variance was explained by environmental variables, whose share was higher in the smallest and intermediate extent than in the broadest extent. Community dissimilarity increased in proportion to differences in altitude and spatial distances at every extent. Accordingly, at all the extents, the selection of releves stratified by altitude or selected taking into account a minimum spatial distance included significantly higher levels of within-habitat beta-diversity, than randomly selected releves. The relation of beta-diversity to the variation in aspect and annual rainfall varied at different extents. Conclusions Our results demonstrate that dry grassland management plans aimed at conserving the maximum within-habitat beta-diversity should take into account variation in environmental variables, among which altitude proved to be a critical factor at every extent. Also, spatial distances positively affect within-habitat beta-diversity levels, and scale-dependent minimum distances among habitat patches should be taken into account when selecting patches of habitat 6210(*) to be conserved in the study area

    Nestin- and Doublecortin-Positive Cells Reside in Adult Spinal CordMeninges and Participate in Injury-Induced Parenchymal Reaction

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    Adult spinal cord has little regenerative potential, thus limiting patient recovery following injury. In this study, we describe a new population of cells resident in the adult rat spinal cord meninges that express the neural stem/precursor markers nestin and doublecortin. Furthermore, from dissociated meningeal tissue a neural stem cell population was cultured in vitro and subsequently shown to differentiate into functional neurons or mature oligodendrocytes. Proliferation rate and number of nestin- and doublecortin-positive cells increased in vivo in meninges following spinal cord injury. By using a lentivirus-labeling approach, we show that meningeal cells, including nestin- and doublecortin-positive cells, migrate in the spinal cord parenchyma and contribute to the glial scar formation. Our data emphasize the multiple roles of meninges in the reaction of the parenchyma to trauma and indicate for the first time that spinal cord meninges are potential niches harboring stem/precursor cells that can be activated by injury. Meninges may be considered as a new source of adult stem/precursor cells to be further tested for use in regenerative medicine applied to neurological disorders, including repair from spinal cord injury
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