Abstract
High-mountain ecosystems are spots of plant diversity in which species composition and traits depict a long evolutionary history of species adaptation to steep environmental gradients. We investigated the main trends in plant species composition and reproductive and dispersal traits (pollen vector, diaspore appendages, dispersal of diaspores and fruit type) in central Mediterranean summits in relation to environmental factors (altitude, aspect, debris cover and slope). Based on 114 plots, with floristic and environmental data collected in the year 2016 on alpine calcareous grasslands in the central Apennines, we explored how species composition varies in relation to environmental factors using CCA (canonical correspondence analysis). Then, we analyzed the relationships among species presence, the occurrence of reproductive and dispersal traits and environmental variables. We used for this analysis the fourth-corner model approach. Our results highlight a consistent response of floristic composition and of structural and ecological characteristics to environmental gradients, with elevation and debris cover being the most important ones. The environmental characteristics of the analyzed ecosystems (e.g., steep slopes and harsh environments) combined with the persistence of perennial plant species already present in each stand, the high precision of pollination and the prevalence of short-distance dissemination strategies should allow the calcareous endemic plant communities of the analyzed Mediterranean summits to be conserved at least for a mid-term period slowing down the expansion of the warm-adapted species, less adapted to the local environmental constrains.
Highlights
Mountain environments throughout the world host highly specialized flora and fauna [1].In Europe, mountain habitats contain approximately 20% of the native flora [2], most of which are endemics and rare [3] and constitute hotspots of plant diversity [1,4,5]
On the left (negative scores on the first (CCA1) axis—Table 2), is composed of cryophilous species such as Crepis pygmaea, Alyssum cuneifolium, Saxifraga exarata subsp. ampullacea, Veronica aphylla and Galium magellensis that tend to occur at higher altitudes in areas rich in debris
There was evidence of a pronounced change in species composition along the altitudinal gradient, with a clear assemblage of species adapted to harsh environmental conditions with poor soils, high debris cover and low temperatures at higher elevations (e.g., Alyssum cuneifolium, Viola magellensis, Galium magellensis) and a group of species living in milder conditions in the lower sectors (Oxytropis campestris, Sesleria juncifolia subsp. juncifolia, Helictochloa praetutiana subsp. praetutiana)
Summary
In Europe, mountain habitats contain approximately 20% of the native flora [2], most of which are endemics and rare [3] and constitute hotspots of plant diversity [1,4,5]. Such diversity is in part due to the particular climatic conditions that rapidly vary over very short distances along altitudinal gradients. Diversity 2018, 10, 58 great biogeographic interest [3] Such mountain environments [6,7,8], are threatened by global warming because of their pronounced orographic discontinuity, which make them worryingly vulnerable to biodiversity loss [9]
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