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Questions: Analysing how multiple facets of biodiversity vary across space and time can help to predict the vulnerability of mountaintop floras to future environmental changes. Here we addressed the following questions: (a) Are elevational patterns of mountaintop plant diversity consistent across taxonomy, function and phylogeny? (b) How have the taxonomic, functional and phylogenetic dimensions of mountaintop plant communities changed over the past two decades? (c) Is the magnitude of these temporal trends dependent on elevation? Location: Dovrefjell, central Norway. Methods: The floristic composition of four mountaintops, spread across an elevational gradient from the tree line to the uppermost margins of vascular plant life, was surveyed every 7 years between 2001 and 2022. Six metrics of taxonomic, functional and phylogenetic richness and differentiation were calculated for each mountaintop and survey. Using these data, we assessed how richness and differentiation metrics varied over space (across the elevational gradient) and over time (between surveys). Results: All diversity metrics decreased towards higher elevations, except phylogenetic differentiation which increased significantly by 7% per 100 m elevational gain. Taxonomic richness remained virtually stable between 2001 and 2022, whereas phylogenetic richness increased by 7.5% per decade. Functional richness also increased, but mainly on the lowest mountaintop, by 17% per decade. No significant temporal trends in taxonomic, functional and phylogenetic differentiation were detected. Conclusions: Our findings underpin rearrangements in the functional and phylogenetic structure of mountain plant communities over the past two decades that cannot be predicted from trends in taxonomic richness alone. This highlights the necessity to look beyond species richness and consider multiple facets of biodiversity when studying environmental change impacts on mountain biodiversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Through changes in climate and other environmental factors, alpine tundra ecosystems are subject to increased cover of erect shrubs, reduced predictability of rodent dynamics and changes in wild and domesticated herbivore densities. To predict the dynamics of these ecosystems, we need to understand how these simultaneous changes affect alpine vegetation. In the long term, vegetation dynamics may depend critically on seedling recruitment. To study drivers of alpine plant seedling recruitment, we set up a field experiment where we manipulated the opportunity for plant–plant interactions through vegetation removal and introduction of willow transplants, the occurrence of herbivory through caging of plots, and then sowed 14 species into the plots. We replicated the experiment in three common alpine vegetation types (heath, meadow and Salix shrubland) and recorded seedling emergence and survival over five years. Strong effects of vegetation removal and substantial differences in recruitment among dominant vegetation types suggested important effects of local vegetation on the recruitment success of vascular‐plant seedlings. Similarly, herbivore exclusion had strong positive effects on recruitment success. This effect arose primarily via reduced seedling mortality in plots from which herbivores had been experimentally excluded and became noticeably stronger over time. In contrast, we detected no consistent effects of experimental willow shrub introduction on seedling recruitment. These results demonstrate that large and small herbivores can affect alpine plant seedling recruitment negatively by trampling and feeding on seedlings. Importantly, the effects became stronger over time, suggesting that effects of herbivory on seedling recruitment accumulates over time and may relate to recruitment phases beyond initial seedling emergence. [ABSTRACT FROM AUTHOR]

The article, Impact of climate change on alpine vegetation of mountain summits in Norway. [ABSTRACT FROM AUTHOR]

• We quantified evaporation and soil and air temperature offsets in forest edges across Europe. • Roughly 10% of European broadleaved forests are affected by altered temperature regimes. • Macroclimate and management affected edge-to-interior temperature offset gradients. • Forest structure and the forest-floor biomass are important drivers of temperature offsets. • Dense forest edges can help mitigate edge influences and protect forest interior microclimates. Global forest cover is heavily fragmented. Due to high edge-to-surface ratios in small forest patches, a large proportion of forests is affected by edge influences involving steep microclimatic gradients. Although forest edges are important ecotones and account for 20% of the global forested area, it remains unclear how biotic and abiotic drivers affect forest edge microclimates at the continental scale. Here we report soil and air temperatures measured in 225 deciduous forest plots across Europe for two years. Forest stands were situated along a latitudinal gradient and subject to a varying vegetation structure as quantified by terrestrial laser scanning. In summer, the average offset of air and soil temperatures in forest edges compared to temperatures outside the forest amounted to -2.8 °C and -2.3 °C, respectively. Edge-to-interior summer temperature gradients were affected by the macroclimate and edge structure. From the edge onwards, larger offsets were observed in dense forest edges and in warmer, southern regions. In open forests and northern Europe, altered microclimatic conditions extended deeper into the forest and gradients were steeper. Canopy closure and plant area index were important drivers of summer offsets in edges, whereas in winter also the forest-floor biomass played a key role. Using high-resolution maps, we estimated that approximately 10% of the European broadleaved forests would be affected by altered temperature regimes. Gradual transition zones between forest and adjacent lands are valuable habitat types for edge species. However, if cool and moist forest interiors are desired, then (i) dense and complex forest edges, (ii) an undisturbed forested buffer zone of at least 12.5 m deep and (iii) trees with a high shade casting ability could all contribute to an increased offset. These findings provide important guidelines to mitigate edge influences, to protect typical forest microclimates and to adapt forest management to climate change. [ABSTRACT FROM AUTHOR]

• We quantified microclimatic temperature buffering along hedgerow-woodland transects across Europe. • Hedgerows are less efficient thermal insulators than woodlands, notably at high ambient temperatures. • Temperatures in hedgerows are most extreme around 10 m from the woodland edges. • Wider hedgerows with a tall and dense tree layer provide better buffering against temperature extremes. Hedgerows have the potential to facilitate the persistence and migration of species across landscapes, mostly due to benign microclimatic conditions. This thermal buffering function may become even more important in the future for species migration under climate change. Unfortunately, there is a lack of empirical studies quantifying the microclimate of hedgerows, particularly at broad geographical scales. Here we monitored sub-canopy temperatures using 168 miniature temperature sensors distributed along woodland-hedgerow transects, and spanning a 1600-km macroclimatic gradient across Europe. First, we assessed the variation in the temperature offset (that is, the difference between sub-canopy and corresponding macroclimate temperatures) for minimum, mean and maximum temperatures along the woodland-hedgerow transects. Next, we linked the observed patterns to macroclimate temperatures as well as canopy structure, overstorey composition and hedgerow characteristics. The sub-canopy versus macroclimate temperature offset was on average 0.10 °C lower in hedgerows than in woodlands. Minimum winter temperatures were consistently lower by 0.10 °C in hedgerows than in woodlands, while maximum summer temperatures were 0.80 °C higher, albeit mainly around the woodland-hedgerow ecotone. The temperature offset was often negatively correlated with macroclimate temperatures. The slope of this relationship was lower for maximum temperatures in hedgerows than in woodlands. During summer, canopy cover, tree height and hedgerow width had strong cooling effects on maximum mid-day temperatures in hedgerows. The effects of shrub height, shrub cover and shade-casting ability, however, were not significant. To our knowledge, this is the first study to quantify hedgerow microclimates along a continental-scale environmental gradient. We show that hedgerows are less efficient thermal insulators than woodlands, especially at high ambient temperatures (e.g. on warm summer days). This knowledge will not only result in better predictions of species distribution across fragmented landscapes, but will also help to elaborate efficient strategies for biodiversity conservation and landscape planning. [ABSTRACT FROM AUTHOR]