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Gentili R.,University of Milan Bicocca | Baroni C.,CNR Institute of Geosciences and Earth Resources | Caccianiga M.,University of Milan | Armiraglio S.,Museo Civico di Science Naturali di Brescia | And 2 more authors.
Ecological Complexity | Year: 2015

During interglacial stages, microrefugia are sites that support locally favorable climates within larger areas with unfavorable warmer climates. Despite recent theoretical representations of microrefugia, an appropriate ecological characterization is still lacking, mostly for warm periods. Across mountain/alpine areas, cold-adapted plant species could adopt different strategies to manage the effects of climate warming: (A) migration toward higher elevations and summits; (B) in situ resilience of communities and species populations within microrefugia; and C) adaptation and evolution by genetic differentiation. This review aims to distinguish and characterize from an ecological perspective glacial, nival, periglacial and composite landforms and deposits that may function as potential microrefugia during interglacial warm periods.We conducted a literature screening related to the geomorphological processes and landforms associated with vegetation and plant communities in alpine/mountain environments of Europe. They include glacial deposits rock glaciers, debris-covered glaciers, composite cones and channels. In Alpine regions, geomorphologic niches that constantly maintain cold-air pooling and temperature inversions are the main candidates for microrefugia. Within such microrefugia, microhabitat diversity modulates the responses of plants to disturbances caused by geomorphologic processes and supports their aptitude for surviving under extreme conditions on unstable surfaces in isolated patches. Currently, European marginal mountain chains may be considered as examples of macrorefugia where relict boreo-alpine species persist within peculiar geomorphological niches that act as microrefugia.This review contributes to identifying potential warm-stage microrefugia areas across alpine and mountain regions and determining certain landforms that play or may play such role under global-change scenarios. The occurrence of warm-stage microrefugia within these locations may be of great importance for the modeling of future distributions of species and assessing the risk of extinction for alpine species. Microrefugia may have important implications in micro-evolutionary processes that occur across alternating climatic phases. © 2014 Elsevier B.V. Source


Gentili R.,University of Milan Bicocca | Armiraglio S.,Museo Civico di Science Naturali di Brescia | Rossi G.,University of Pavia | Sgorbati S.,University of Milan Bicocca | Baroni C.,University of Pisa
Flora: Morphology, Distribution, Functional Ecology of Plants | Year: 2010

Composite channels in the alpine region are heterogeneous environments resulting from a variety of erosive and depositional processes. They can have different ecological functions: habitats for plant species, conduits, filters, sources and sinks. They can contain sparse, intermittent vegetation cover, and are frequently free of vegetation except along the banks and levees. We hypothesised that this disturbed and fragmented landscape unit encourages biodiversity with characteristic plant species adapted to survive in the channel niches. In this study, which was carried out mostly in the subalpine belt of the Adamello-Presanella Group, we aimed to characterize floristic and biodiversity patterns with respect to the dominant channel gradients by means of a canonical correspondence analysis (CCA) ordination approach and an analysis of diversity indexes. The frequency table and CCA results showed considerable floristic heterogeneity within the composite channels mainly as a function of nutrient availability and altitude. Different gradients of biodiversity (alpha, beta and gamma diversity) depended on the geomorphological disturbances (alpha and gamma) and environmental heterogeneity across the channel subunits. Geomorphological processes seem to play key roles in the dispersal of seeds, spores and propagules and in the colonization, establishment and spread of plants in this complex environment. The composite channels could play an important refuge-habitat function for microthermic species during the widely accepted current trend of global warming. © 2009 Elsevier GmbH. Source


Gentili R.,University of Milan Bicocca | Armiraglio S.,Museo Civico di Science Naturali di Brescia | Sgorbati S.,University of Milan Bicocca | Baroni C.,CNR Institute of Geosciences and Earth Resources
Plant Ecology | Year: 2013

The altitudinal gradient is considered as a stress gradient for plant species because the development and fitness of plant communities tend to decrease as a result of the extreme environmental conditions present at high elevations. Abiotic factors are predicted to be the primary filter for species assemblage in high alpine areas, influencing biotic interactions through both competition for resources and positive interactions among species. We hypothesised that the relative importance of the ecological driving forces that affect the biotic interactions within plant communities changes along an elevation gradient on alpine debris slopes. We used multiple gradient analyses of 180 vegetation plots along an altitudinal range from ~1,600 to 2,600 m and single 100 m-bands in the Adamello-Presanella Group (Central Alps) to investigate our hypothesis; we measured multiple environmental variables related to different ecological driving forces. Our results illustrate that resource limitations at higher elevations affect not only the shift from competition to facilitation among species. A geomorphological disturbance regime along alpine slopes favours the resilience of the high-altitude species within topographic/geomorphological traps. An understanding of the ecological driving forces and positive interactions as a function of altitude may clarify the mechanisms underlying plant responses to present and future environmental changes. © 2013 Springer Science+Business Media Dordrecht. Source


Gilardelli F.,University of Milan Bicocca | Sgorbati S.,University of Milan Bicocca | Armiraglio S.,Museo Civico di Science Naturali di Brescia | Citterio S.,University of Milan Bicocca | Gentili R.,University of Milan Bicocca
Plant Biosystems | Year: 2015

We investigated spontaneous vegetation succession and the relationship between time and vegetation patterns in several abandoned quarries of the Botticino extraction basin (Lombardy, Italy) and then assigned plant assemblages to a predetermined theoretical successional phase using an original procedure. To recognise and validate the gradient due to time, an ordination approach of vegetation plots linked to constant variables and time since last mining Canonical Correspondence Analysis was conducted first. Then, to determine the durations of the vegetation succession phases and trends between the colonisers and late successional species, we used an original six-step procedure based primarily on the regression curve of the percent relative abundance of life forms (RALFs) over time. The results demonstrated that time is the primary factor that significantly affects life form turnover during succession. Vegetation establishment and development in the “pioneer phase” (0–6 years) were affected by abiotic filters, which determined the dominance of a few ruderal and annual/alien species, mostly therophytes. The successive phases were characterised by an increasing presence of perennial species (mostly phanerophytes) with a consequent influence of biotic filters. The RALF procedure may be applied to other environments to investigate the time trends of plant communities during successions. © 2015 Società Botanica Italiana Source


Marchetti L.,University of Padua | Ronchi A.,University of Pavia | Santi G.,University of Pavia | Schirolli P.,Museo Civico di Science Naturali di Brescia | Conti M.A.,University of Rome La Sapienza
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

The recent studies on Permian captorhinomorph (non-diapsid eureptile) footprints from North America, North Africa, and Europe raised the interest on their taxonomic and biostratigraphic significance. They seem to radiate in the late Early Permian, but the scarcity of absolute dating in the classic sections bearing these trace fossils is not helpful in order to unravel their distribution. The continental Collio Formation cropping out extensively in the central Southern Alps of Italy can cover this gap of knowledge, since it preserves a rich testimony of these trace fossils (Erpetopus, Hyloidichnus, Varanopus) and it is well-constrained from radiometric datings and fossil content. For this and because of the huge amount of stored but unanalyzed material, a revision was necessary, through careful taxonomic assignations. These taxa are here confirmed and/or identified as being: Amphisauropus kablikae, cf. Batrachichnus isp., Dromopus lacertoides, Erpetopus cassinisi, Hyloidichnus bifurcatus, Limnopus heterodactylus and Varanopus isp. The occurrence of Erpetopus at the base of the Collio Formation (Kungurian base) suggests its minimum age of first appearance in a global context: this is a very important presence in order to build a reliable tetrapod footprint biostratigraphy during the Permian. The quantity of material yielded in the different facies of the Collio and Dosso dei Galli Formations also permit new insights on the paleoenvironments and climatic settings. © 2015. Source

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