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Global changes are recognized as one of the main drivers of biodiversity changes over time, especially in mountain ecosystems. A key approach to detect and investigate the effect of climate and land use change on these ecosystems is represented by vegetation surveys. In this study, based on the resurvey of historical vegetation data, we assessed temporal beta-diversity patterns within and between subalpine and alpine vegetation types in the Dolomiti Bellunesi National Park. Resurvey was focussed on plots sampled in four main vegetation types: 1 and 2) Mesophytic and xerophytic grasslands on neutral or base-rich soils respectively dominated by Sesleria caerulea and Carex sempervirens and by Sesleria caerulea and Helictotrichon parlatorei; 3) Acidophytic grasslands dominated by Nardus stricta; 4) Snowbeds with dominance of dwarf willows (Salix herbacea or S. retusa) or Luzula alpinopilosa. Our results revealed a pattern of floristic homogenization in grasslands and snowbeds indicating a decreasing heterogeneity, both within and between different vegetation types that can be associated with different components of global change. The highest temporal beta diversity and floristic homogenization were detected in snowbeds. In general, the magnitude of temporal changes differ between communities, thus claiming for conservation activities that are tailored to each vegetation type. [ABSTRACT FROM AUTHOR]

We announce the formation of the "GLORIA ITALIA NETWORK" and present an overview of the Italian alpine plant communities changes that have occurred in the last 20 years. This network will provide coordination between Italian GLORIA sites and enhance public awareness of changes in alpine plant diversity under climate change. [ABSTRACT FROM AUTHOR]

High-elevation habitats host a large number of plant species and are characterized by high biodiversity. The vegetation dynamics in these cold adapted ecosystems are difficult to predict, being affected by global warming, especially in the last decades. With the aim to promote a better understanding of climate-driven changes of alpine vegetation, we investigated the variation in species richness, α-diversity, β-diversity, and total cover of plant functional types over a time lapse of 15 years, relying on multiple re-surveys of mountain summit vegetation in 2001, 2008 and 2015. The study area, included in the long term global observation network GLORIA, was at the boundary between temperate and Mediterranean mountains of S-Europe (northern Apennines, Italy). We identified a trend of loss in biodiversity and signals of biotic homogenization using multiple diversity metrics, despite the overall species richness increment observed in the study area. Cold-adapted and rare species declined while dominant species like graminoids and shrubs increased. Our results highlight that long-term vegetation monitoring activities paired with multiple measures of diversity are required to properly assess biodiversity and to obtain useful indications for future conservation activities in alpine environments. The methods here presented could be applied in all GLORIA sites to quantify biodiversity changes over time, obtaining comparable results for biodiversity monitoring in high-elevation habitats from all over the world. [ABSTRACT FROM AUTHOR]

Alpine snowbed communities are among the habitats most threatened by climate change. The warmer temperature predicted, coupled with advanced snowmelt time, will influence flowering phenology, which is a key process in species adaptation to changing environmental conditions and plant population dynamics. However, we know little about the effects of changing micro-climate on flowering time in snowbeds and the mechanisms underlying such phenological responses. The flowering phenology of species inhabiting alpine snowbeds was assessed with weekly observations over five growing seasons. We analysed flowering time in relation to micro-climatic variation in snowmelt date, soil and air temperature, and experimental warming during the snow-free period. This approach allowed us to test hypotheses concerning the processes driving flowering phenology. The plants were finely tuned with inter-annual and intra-seasonal variations of their micro-climate, but species did not track the same micro-climatic feature to flower. At the growing-season time-scale, the air surrounding the plants was the most common trigger of the blooming period. However, at the annual time-scale, the snowmelt date was the main controlling factor for flowering time, even in warmer climate. Moreover, spatial patterns of the snowmelt influenced the developmental rate of the species because in later snowmelt sites the plants needed a lower level of heat accumulation to enter anthesis. Phenological responses to experimental warming differed among species, were proportional to the pre-flowering time-span of plants, and did not show consistent trends of change over time. Finally, warmer temperature produced an overall increase of flowering synchrony both within and among plant species. [ABSTRACT FROM AUTHOR]

Background and aims: In cold biomes, litter decomposition, which controls the nutrient availability for plants and the ecosystem carbon budget, is strongly influenced by climatic conditions. In this study, focused on the early litter decay within snowbed habitats, the magnitude of the short- and long-term influences of climate warming, the direction of the effects of warmer temperature and advanced snowmelt, and the control of microclimatic features and plant traits were compared. Methods: Combining experimental warming and space-for-time substitution, mass loss and nutrient release of different plant functional types were estimated in different climatic treatments with the litter bag method. Results: Plant functional types produced a larger variation in the early-decomposition compared to that produced by climatic treatments. Litter decay was not affected by warmer summer temperatures and reduced by advanced snowmelt. Structural-related plant traits exerted the major control over litter decomposition. Conclusions: Long-term effects of climate warming, resulting from shifts in litter quality due to changes in the abundance of plant functional types, will likely have a stronger impact on plant litter decomposition than short-term variations in microclimatic features. This weaker response of litter decay to short-term climate changes may be partially due to the opposite influences of higher summer temperatures and advanced snowmelt time. [ABSTRACT FROM AUTHOR]

Abstract: Within the alpine life zone, snowbeds are regarded as especially vulnerable to the predicted decrease in snowfall and may be considered as a suitable habitat for studies concerning the effects of global changes on alpine vegetation. This paper investigated the influences of snow-free period on species richness, density and primary production in a late snowbed dominated by the moss Polytrichastrum sexangulare. An historical average difference of 2.4 weeks in the release from snow cover did not affect either density or production of the dominant species. In contrast, vascular plant species richness was limited by the length of growing season, and some vascular species showed differences in density and production between late and early snow-free stands. Moreover, total vascular species production was found to be markedly higher in the early snow-free stands. These results suggest that, in this extreme habitat, vascular plant species richness, density and production are very responsive to variation in the snow cover period. Accordingly, both structural properties and functional processes in this habitat may be noticeably altered, within a climatic global change scenario. [Copyright &y& Elsevier]