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High mountain ecosystems and their biota are governed by low-temperature conditions and thus can be used as indicators for climate warming impacts on natural ecosystems, provided that long-term data exist. We used data from the largest alpine to nival permanent plot site in the Alps, established in the frame of the Global Observation Research Initiative in Alpine Environments (GLORIA) on Schrankogel in the Tyrolean Alps, Austria, in 1994, and resurveyed in 2004 and 2014. Vascular plant species richness per plot increased over the entire period, albeit to a lesser extent in the second decade, because disappearance events increased markedly in the latter period. Although presence/absence data could only marginally explain range shift dynamics, changes in species cover and plant community composition indicate an accelerating transformation towards a more warmth-demanding and more drought-adapted vegetation, which is strongest at the lowest, least rugged subsite. Divergent responses of vertical distribution groups of species suggest that direct warming effects, rather than competitive displacement, are the primary causes of the observed patterns. The continued decrease in cryophilic species could imply that trailing edge dynamics proceed more rapidly than successful colonisation, which would favour a period of accelerated species declines.

In this study we provide the first comprehensive assessment of the environmental and anthropogenic factors driving bryophyte invasions worldwide. We compiled data of alien bryophyte distributions from 82 regions on five continents and oceanic islands and region specific variables. For each species, we collected data on its region-specific invasion stage, i.e. casual (ephemeral) vs naturalized (persistent) occurrences, and we differentiated between known aliens and those which are likely to be alien (cryptogenic). We used these data to test how species attributes, environmental and socio-economic conditions of the study areas as well as introduction effort affect invasion probabilities at different invasion stages and of known alien vs cryptogenic species. We collected information on species' attributes (native range size and location, niche breadth, habitat affiliation), and calculated variables characterising the environmental, biogeographic and socio-economic features of the native and recepient regions. Subsequently, we related the probability of alien occurrence across different invasion stages with these species- and region-wise predictor variables using generalized linear mixed effects models. Greater native range size raised the likelihood that a species becomes alien or cryptogenic. Islands are more invaded by alien (and cryptogenic) bryophytes than continental regions. Native range size and socio-economic activity increase the likelihood that a species becomes alien or cryptogenic elsewhere. Interestingly, among alien bryophytes naturalizations occur more frequently in regions of the complementary hemisphere than in regions of their native hemisphere. In general, regions in the Southern Hemisphere have higher numbers of naturalized bryophytes. We conclude that there is a conspicuous change in factors determining bryophyte invasions at different invasion stages. Whereas alien and cryptogenic bryophyte species occurrences are more frequent on islands and depend on native range size, and hence probably propagule pressure, naturalized bryophytes are more frequent in areas which are biogeographically separated but climatically similar to the native ranges.

High mountain areas above the alpine zone are, despite the low-temperature conditions, inhabited by evolutionary and functionally differing organism groups. We compared the abundance and species richness of vascular plants, oribatid mites, springtails, spiders, and beetles, as well as bacterial and methanogenic archaeal prokaryotes (only abundance), at 100 m vertical intervals from 2,700-3,400 m in the Central Alps. We hypothesized that the less mobile microarthropods and microorganisms are more determined by and respond in similar ways to soil properties as do vascular plants. In contrast, we expected the more mobile surface-dwelling groups to forage also in places devoid of vegetation and thus to show patterns that deviate from that of vascular plants. Surprisingly, the observed patterns were diametrically opposed to our expectations: soil-living oribatid mites and springtails showed high individual numbers at high elevations, even where vascular plants barely occurred. Springtails also showed a rather constant species richness throughout the entire gradient. In contrast, patterns of surface-dwelling organisms and of archaeal prokaryotes did not differ significantly from vascular plants, because of either comparable climate sensitivity or their dependency on vegetated habitats. This study may serve as a baseline to estimate the risks of biodiversity losses in response to climate change across different biotic ecosystem components and to explore the potential and limitations of vascular plants as proxy for other organism groups that are far more challenging to monitor.

Abstract Mediterranean high mountain grasslands are shaped by climatic stress and understanding their functional adaptations can contribute to better understanding ecosystems’ response to global change. The present work analyses the plant functional traits of high-elevation grasslands growing in Mediterranean limestone mountains to explore, at the community level, the presence of different plant strategies for resource use (conservative vs. acquisitive) and functional diversity syndromes (convergent or divergent). Thus, we compared the functional composition and diversity of the above-ground traits related to resource acquisition strategies of subalpine and alpine calcareous grasslands in the central Apennines, a mountain region characterized by a dry-summer Mediterranean climate. We used georeferenced vegetation plots and field-measured plant functional traits (plant maximum height, specific leaf area and leaf dry matter content) for the dominant species of two characteristic vegetation types: the subalpine Sesleria juncifolia community and the alpine Silene acaulis community. Both communities are of particular conservation concern and are rich in endemic species for which plant functional traits are measured here for the first time. We analysed the functional composition and diversity using the community-weighted mean trait index and the functional diversity using Rao’s function, and we assessed how much the observed pattern deviated from a random distribution by calculating the respective standardized effect sizes. The results highlighted that an acquisitive resource use strategy and relatively higher functional diversity of leaf traits prevail in the alpine S. acaulis community, optimizing a rapid carbon gain, which would help overcome the constraints exerted by the short growing season. The divergent functional strategy underlines the co-occurrence of different leaf traits in the alpine grasslands, which shows good adaptation to a microhabitat-rich environment. Conversely, in the subalpine S. juncifolia grassland, a conservative resource use strategy and relatively lower functional diversity of the leaf traits are likely related to a high level resistance to aridity over a longer growing season. Our outcomes indicate the preadaptation strategy of the subalpine S. juncifolia grassland to shift upwards to the alpine zone that will become warmer and drier as a result of anthropogenic climate change. Mediterranean high mountain grasslands are shaped by climatic stress and understanding their functional adaptations can contribute to better understanding ecosystems’ response to global change. We analysed, at the community level, above-ground plant strategies for resource use and functional diversity syndrome in calcareous grasslands. We observed a more acquisitive resource use strategy and a higher functional diversity in the alpine with respect to the subalpine grasslands in which instead plant traits look more conservative. Subalpine grasses seem more resistant to aridity and well preadapted for shifting upwards into the alpine zone which is getting warmer and drier.

Maintaining and improving the state of biodiversity is a primary factor guiding management activities in conservation areas, including protected areas (PAs) and other effective area-based conservation measures (OECMs). Due to the complex nature of conservation programs, a common management approach cannot be prescribed. Robust monitoring programs supporting management activities are required to evaluate the state of species and habitats. However, limited resources, poor data management practices, and competing requirements of stakeholder groups increase the challenges that must be addressed through realization of monitoring programs. We propose a framework of seven basic questions to guide conservation area managers to implement effective biodiversity monitoring techniques. The result is identification of indicators, site characteristics, and resources to promote the development of a biodiversity monitoring program. We call for adoption of a strategic guideline providing this framework to harmonize decision making processes across national and international networks. Implementation of this robust framework will support comparative monitoring data, contributing to systematic approaches for adaptive management in PAs and OECMs and improving the body of knowledge surrounding global biodiversity.

Based on data of bryophyte invasions into 82 regions on five continents of both hemispheres, we aim here at a first comprehensive overview of the impacts that bryophytes may have on biodiversity and socio-economy. Of the 139 bryophytes species which are alien in the study regions seven cause negative impacts on biodiversity in 26 regions, whereas three species cause negative impacts on socio-economic sectors in five regions. The vast majority of impacts stem from anecdotal observations, whereas only 14 field or experimental studies (mostly on Campylopus introflexus in Europe) have quantitatively assessed the impacts of an alien bryophyte. The main documented type of impact on biodiversity is competition (8 alien bryophytes), with native cryptogams being most affected. In particular, C. introflexus (9 regions) and Pseudoscleropodium purum (7 regions) affect resident species composition. The few socio-economic impacts are caused by alien bryophytes which form dense mats in lawns and are then considered a nuisance. Most negative impacts on biodiversity have been recorded in natural grasslands, forests, and wetlands. Impacts of alien bryophytes on biodiversity and socio-economy are a recent phenomenon, with >85 % of impacts on biodiversity, and 80 % of impacts on socio-economy recorded since 1990. On average, 40 years (impacts on biodiversity) and 25 years (impacts on socio-economy) elapsed between the year a bryophyte species has been first recorded as alien in a region and the year impacts have been recorded first. Taking into account the substantial time lag between first record and first recorded impact in a region, it seems to be likely that the currently moderate impacts of alien bryophytes will continue to increase. As quantitative studies on impacts of alien bryophytes are rare and restricted to few environments and biogeographic regions, there is a need for addressing potential impacts of alien bryophytes in yet understudied settings.

We assess and review spatio-temporal patterns, habitat affiliations, pathways, impacts, and management experience of bryophyte invasions in extra-tropical countries and regions (n = 82) from five continents and maritime islands spanning both hemispheres. Distribution data were extracted and critically checked from a wide range of sources and supplemented with data on biology and introduction history. We identified 139 bryophytes species which we consider to be alien in at least one of our study regions (106 mosses, 28 hepatics and 5 hornworts). Numbers of average alien bryophyte species are significantly higher on islands than in continental regions of similar size, and peak on maritime islands. Cumulative numbers of first records have grown slowly until 1950 and have strongly increased since then. Accidental import as hitch-hiker (34 species) or with ornamental plants (27 species) constitute the most important introduction pathways. We found a remarkably high contribution from distant donor regions to alien bryophyte floras, especially from the complementary hemisphere. Most alien bryophytes prefer strongly modified habitats (e.g. ruderal vegetation, roadsides, lawns), and only few natural ecosystems (forests, rocks) are regularly invaded. Evidence for an ecological impact of bryophyte invasions is scarce and competitive replacement of native moss species, or vascular plant seedlings, by alien bryophytes has only been documented in a few cases. We conclude that bryophytes differ profoundly in many respects from vascular plants, and so do their invasion patterns at large scale. Our global bryophyte invasion state assessment provides the basis for future, more explicit considerations of this largely neglected taxonomic group in invasion ecology, a step we suggest to be urgently needed as studying them might provide novel insights into patterns and processes of plant invasions in general.

Recently, Patiño & Vanderpoorten (2015, Journal of Biogeography, 42, doi:10.1111/jbi.12492) commented on our manuscripts about patterns and processes of global bryophyte invasions. In particular, they argued that the criteria we have used to identify alien bryophytes (i.e. anomalous geographical distribution, preference for disturbed habitats, indirect associations with some means of human transport) are insufficient in the absence of further evidence. We fully agree with this statement. Consequently, we had used the abovementioned criteria only for the identification of 'cryptogenic' (i.e. probable alien) species and have stated this explicitly in our manuscripts. Thus, we conclude that Patino & Vanderpoorten (2015) have drawn misleading conclusions on the way we defined aliens. Nevertheless, we acknowledge that given the excellent longdistance dispersal capacities of bryophytes, diverging opinions between different experts on the native, alien or cryptogenic status of a particular bryophyte species in a given region do sometimes exist.

Highly accurate 3D micro topographic mapping in mountain research demands for light equipment and low cost solutions. Recent developments in structure from motion and dense matching techniques provide promising tools for such applications. In the following, the feasibility of terrestrial photogrammetry for mapping topographic location properties of sparsely vegetated areas in selected European mountain regions is investigated. Changes in species composition at alpine vegetation locations are indicators of climate change consequences, such as the pronounced rise of average temperatures in mountains compared to the global average. Better understanding of climate change effects on plants demand for investigations on a micro-topographic scale. We use professional and consumer grade digital single-lens reflex cameras mapping 288 plots each 3 x 3 m on 18 summits in the Alps and Mediterranean Mountains within the GLORIA (GLobal Observation Research Initiative in Alpine environments) network. Image matching tests result in accuracies that are in the order of millimetres in the XY-plane and below 0.5 mm in Z-direction at the second image pyramid level. Reconstructing vegetation proves to be a challenge due to its fine and small structured architecture and its permanent movement by wind during image acquisition, which is omnipresent on mountain summits. The produced 3D point clouds are gridded to 6 mm resolution from which topographic parameters such as slope, aspect and roughness are derived. At a later project stage these parameters will be statistically linked to botanical reference data in order to conclude on relations between specific location properties and species compositions.

Highly accurate 3D micro topographic mapping in mountain research demands for light equipment and low cost solutions. Recent developments in structure from motion and dense matching techniques provide promising tools for such applications. In the following, the feasibility of terrestrial photogrammetry for mapping topographic location properties of sparsely vegetated areas in selected European mountain regions is investigated. Changes in species composition at alpine vegetation locations are indicators of climate change consequences, such as the pronounced rise of average temperatures in mountains compared to the global average. Better understanding of climate change effects on plants demand for investigations on a micro-topographic scale. We use professional and consumer grade digital single-lens reflex cameras mapping 288 plots each 3 x 3 m on 18 summits in the Alps and Mediterranean Mountains within the GLORIA (GLobal Observation Research Initiative in Alpine environments) network. Image matching tests result in accuracies that are in the order of millimetres in the XY-plane and below 0.5 mm in Z-direction at the second image pyramid level. Reconstructing vegetation proves to be a challenge due to its fine and small structured architecture and its permanent movement by wind during image acquisition, which is omnipresent on mountain summits. The produced 3D point clouds are gridded to 6 mm resolution from which topographic parameters such as slope, aspect and roughness are derived. At a later project stage these parameters will be statistically linked to botanical reference data in order to conclude on relations between specific location properties and species compositions.