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Climate warming is causing a shift in biological communities in favor of warm-affinity species (i.e., thermophilization). Species responses often lag behind climate warming, but the reasons for such lags remain largely unknown. Here, we analyzed multidecadal understory microclimate dynamics in European forests and show that thermophilization and the climatic lag in forest plant communities are primarily controlled by microclimate. Increasing tree canopy cover reduces warming rates inside forests, but loss of canopy cover leads to increased local heat that exacerbates the disequilibrium between community responses and climate change. Reciprocal effects between plants and microclimates are key to understanding the response of forest biodiversity and functioning to climate and land-use changes.

1. The ongoing changes to climate challenge the conservation of forest biodiversity. Yet, in thermally limited systems, such as temperate forests, not all species groups might be affected negatively. Furthermore, simultaneous changes in the disturbance regime have the potential to mitigate climate-related impacts on forest species. Here, we (i) investigated the potential long-term effect of climate change on biodiversity in a mountain forest landscape, (ii) assessed the effects of different disturbance frequencies, severities and sizes and (iii) identified biodiversity hotspots at the landscape scale to facilitate conservation management. 2. We employed the model iLand to dynamically simulate the tree vegetation on 13 865 ha of the Kalkalpen National Park in Austria over 1000 years, and investigated 36 unique combinations of different disturbance and climate scenarios. We used simulated changes in tree cover and composition as well as projected temperature and precipitation to predict changes in the diversity of Araneae, Carabidae, ground vegetation, Hemiptera, Hymenoptera, Mollusca, saproxylic beetles, Symphyta and Syrphidae, using empirical response functions. 3. Our findings revealed widely varying responses of biodiversity indicators to climate change. Five indicators showed overall negative effects, with Carabidae, saproxylic beetles and tree species diversity projected to decrease by more than 33%. Six indicators responded positively to climate change, with Hymenoptera, Mollusca and Syrphidae diversity projected to increase more than twofold. 4. Disturbances were generally beneficial for the studied indicators of biodiversity. Our results indicated that increasing disturbance frequency and severity have a positive effect on biodiversity, while increasing disturbance size has a moderately negative effect. Spatial hotspots of biodiversity were currently found in low- to mid-elevation areas of the mountainous study landscape, but shifted to higher-elevation zones under changing climate conditions. 5. Synthesis and applications. Our results highlight that intensifying disturbance regimes may alleviate some of the impacts of climate change on forest biodiversity. However, the projected shift in biodiversity hotspots is a challenge for static conservation areas. In this regard, overlapping hotspots under current and expected future conditions highlight priority areas for robust conservation management.

To assess the geographical transferability of niche-based species distribution models fitted with two modelling techniques. Two distinct geographical study areas in Switzerland and Austria, in the subalpine and alpine belts. Generalized linear and generalized additive models (GLM and GAM) with a binomial probability distribution and a logit link were fitted for 54 plant species, based on topoclimatic predictor variables. These models were then evaluated quantitatively and used for spatially explicit predictions within (internal evaluation and prediction) and between (external evaluation and prediction) the two regions. Comparisons of evaluations and spatial predictions between regions and models were conducted in order to test if species and methods meet the criteria of full transferability. By full transferability, we mean that: (1) the internal evaluation of models fitted in region A and B must be similar; (2) a model fitted in region A must at least retain a comparable external evaluation when projected into region B, and vice-versa; and (3) internal and external spatial predictions have to match within both regions. The measures of model fit are, on average, 24% higher for GAMs than for GLMs in both regions. However, the differences between internal and external evaluations (AUC coefficient) are also higher for GAMs than for GLMs (a difference of 30% for models fitted in Switzerland and 54% for models fitted in Austria). Transferability, as measured with the AUC evaluation, fails for 68% of the species in Switzerland and 55% in Austria for GLMs (respectively for 67% and 53% of the species for GAMs). For both GAMs and GLMs, the agreement between internal and external predictions is rather weak on average (Kulczynski's coefficient in the range 0.3-0.4), but varies widely among individual species. The dominant pattern is an asymmetrical transferability between the two study regions (a mean decrease of 20% for the AUC coefficient when the models are transferred from Switzerland and 13% when they are transferred from Austria). The large inter-specific variability observed among the 54 study species underlines the need to consider more than a few species to test properly the transferability of species distribution models. The pronounced asymmetry in transferability between the two study regions may be due to peculiarities of these regions, such as differences in the ranges of environmental predictors or the varied impact of land-use history, or to species-specific reasons like differential phenotypic plasticity, existence of ecotypes or varied dependence on biotic interactions that are not properly incorporated into niche-based models. The lower variation between internal and external evaluation of GLMs compared to GAMs further suggests that overfitting may reduce transferability. Overall, a limited geographical transferability calls for caution when projecting niche-based models for assessing the fate of species in future environments.

Human activity over the past century has greatly disrupted the natural nitrogen (N) balance, harming health and the environment. Sustainable nitrogen management requires cross-sectoral governance, but studies tracking nitrogen flows across sectors are limited. This study assesses cross-sectoral sources, flows, and sinks of reactive nitrogen (Nr) in Austria, identifying direct Nr inputs and emitting sectors. Using the ‘UNECE-Guidance Document on National Nitrogen Budgets’ and material flow analysis, we quantified Austria’s national nitrogen budget for 2015–2019. Results show the main nitrogen inflows and outflows from imports and exports in the consumer goods and chemical industries. Energy imports also contribute significantly. Some nitrogen is temporarily stored (e.g. in products) or transferred between sectors. However, not all of this N-loss is of direct environmental concern. Annually, 389 kt Nr are lost directly to the environment and causing significant environmental and economic consequences. Direct Nr inputs primarily originate from agriculture (39.3%) and energy/transport (20.7%), with around 30% from cross-border fluxes via water (13.9%) and air (16.6%). The remaining 10% stem from settlements, waste management, and industry. This study highlights the complexity of nitrogen sources and sinks in Austria and underscores the need for improvements towards reduced uncertainties in future research, including higher-resolution spatial data to account for regional variability.

Assessments of synergies and trade-offs between climate change mitigation and forest biodiversity conservation have focused on set-aside areas. We evaluated a more comprehensive portfolio of silvicultural management adaptations to climate change and conservation measures exemplary for managed European beech forests. Based on the available literature, we assessed a range of common silvicultural management and conservation measures for their effects on carbon sequestration in forest and wood products and for substituting more carbon-intensive products. We complemented this review with carbon sequestration simulations for a typical mountainous beech forest region in Austria. We propose three priority actions to enhance the synergies between climate change mitigation and biodiversity. First, actively increase the proportion of European beech in secondary Norway spruce forests, even though beech will not be unaffected by expected water supply limitations. Secondly, optimize the benefits of shelterwood systems and promote uneven-aged forestry, and thirdly, enhance mixed tree species. Targeted conservation measures (deadwood, habitat trees, and old forest patches) increase the total C storage but decrease the annual C sequestration in forests, particularly in wood products. The establishment of a beech wood market with an extended product portfolio to reduce the use of fuelwood is essential for sustainable climate change mitigation. Since there are limitations in the production of saw timber quality beech wood on low fertility sites, C accumulation, and biodiversity can be emphasized in these areas.

Aim: Reports on recent changes in high-mountain vegetation are mostly based on re-surveys of mountaintop floras. Summits are very specific habitats, however, and detected trends may not necessarily represent alpine vegetation in general. Here, we analyse re-samples of three prevalent plant communities in non-summit alpine habitats (snowbeds, two grassland types). Location: Northeastern European Alps. Methods: In 2013 we re-sampled a total of 91 relevés of three plant communities from the 1990s. We compared original and re-samples in terms of species richness (α-diversity), pair-wise compositional dissimilarity (β-diversity) and species pool size (γ-diversity). Moreover, we calculated mean ecological indicator values (temperature, moisture, nutrient status and soil acidity) as well as potential plant height for each of the 182 relevés. Differences in species pool sizes between the two sampling campaigns were evaluated by randomization tests based on rarefaction curves. In all other cases, differences were compared using paired i-tests or Kruskal-Wallis tests. Results: Of all the community attributes analysed, changes were most consistent with respect to increasing mean species' temperature indicator values. Mean potential plant height also increased slightly in all three communities, but differences were statistically significant only in the case of Carex sempervirens grasslands. Changes in species richness varied among communities, with only the Carex firma grasslands accumulating significantly more species at both the local and regional scales. For the other two plant communities, α- and γ-diversity remained constant, but β-diversity increased. Indicator values other than temperature either did not change or changed idiosyncratically in the different communities. Conclusions: Our results indicate that some long-term changes occurred in high mountain grassland and snowbed vegetation of the study area. Consistent changes in mean species' temperature indicator values suggest that climate warming was an important driver. However, trends in biodiversity metrics differed substantially between the studied communities. We conclude that recent increase in species numbers commonly reported from temperate and boreal mountaintops cannot readily be generalized to all temperate and boreal high-mountain vegetation.

Aim Assessing potential response of alpine plant species distribution to different future climatic and land-use scenarios. Location Four mountain ranges totalling 150 km2in the north-eastern Calcareous Alps of Austria. Methods Ordinal regression models of eighty-five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land-use impacts on vegetation patterns in combination with climatic changes. Results A regionalized GCM scenario for 2050 (+ 0.65 ° C, -30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 ° C, -30 mm August precipitation; + 2 ° C, -60 mm August precipitation) however, will bring about a severe contraction of the alpine, non-forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 ° C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non-forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved.

1 Global warming will probably shift treelines upslope in alpine areas and towards the pole in arctic environments. However, responses of regional treelines to climatic trends over the last century do not show any clear trends. We hypothesize that these equivocal responses may partly be caused by limitation of dispersal and/or recruitment that is species-specific to particular trees with potentially expanding ranges. 2 To test this hypothesis, we established and parameterized a temporally and spatially explicit model of plant spread and analysed its sensitivity to: (a) variation in predicted climatic trends; (b) the spatial distribution of recruits around a seed source; and (c) variation in the resistance of resident non-woody vegetation to invasion. We used data from a high mountain landscape of the Northern Calcareous Alps in Austria where the treeline is dominated by Pinus mugo Turra, a shrubby pine. 3 Low growth rates and long generation times, together with considerable dispersal and recruitment limitation, resulted in an overall slow range expansion under various climate-warming scenarios. 4 Running the model for 1000 years predicted that the area covered by pines will increase from 10% to between 24% and 59% of the study landscape. 5 The shape of the dispersal curve and spatial patterns of competitively controlled recruitment suppression affect range size dynamics at least as severely as does variation in assumed future mean annual temperature (between 0 °C and 2 °C above the current mean). Moreover, invasibility and shape of the dispersal curve interact with each other due to the spatial patterns of vegetation cover in the region. 6 Ambiguous transient responses of individual treeline systems may thus originate not only from variation in regional climatic trends but also from differences in species' dispersal and recruitment behaviour and in the intensity and pattern of resistance of resident alpine vegetation to invasion.

More and more ecologists have started to resurvey communities sampled in earlier decades to determine long-term shifts in community composition and infer the likely drivers of the ecological changes observed. However, to assess the relative importance of and interactions among multiple drivers, joint analyses of resurvey data from many regions spanning large environmental gradients are needed. In this article, we illustrate how combining resurvey data from multiple regions can increase the likelihood of driver orthogonality within the design and show that repeatedly surveying across multiple regions provides higher representativeness and comprehensiveness, allowing us to answer more completely a broader range of questions. We provide general guidelines to aid the implementation of multiregion resurvey databases. In so doing, we aim to encourage resurvey database development across other community types and biomes to advance global environmental change research.

Wide-spread fragmentation and isolation of habitats with high nature conservation value lends increasing importance to a better understanding of the factors which determine species richness in isolated habitat patches. Using data of one of the most abundant invertebrate groups in grasslands, Orthoptera, we analysed how species richness and distribution in 60 isolated semi-natural grassland remnants in Austria were affected by five environmental variables (altitude, habitat and land use diversity within each patch, habitat diversity of areas adjacent to each patch, patch size), and related to diversity of their main food source, i.e. vascular plants. We found a significant positive correlation between Orthoptera and vascular plant species richness, with threatened Orthoptera species having the lowest correlation coefficients. Life form diversity of plants was only moderately positively correlated with Orthoptera species richness. Habitat diversity within and adjacent to the grassland patch had by far the highest loadings on the first two axes of the principal component analysis, which jointly explained 99 % of the variance, and proved to be significant for total, threatened and not threatened Orthoptera, as well as for the two Orthoptera orders occurring in Central Europe (Caelifera, Ensifera). Additionally, the distribution of the majority of those 14 Orthoptera species analysed individually was mainly correlated with habitat diversity within and adjacent to the grassland patch. However, the distribution of a significant proportion of species was associated with other factors: five species were closely related to on-site land use diversity and patch size, and the distribution of three Ensifera species was not significantly correlated to any of the explanatory variables. We conclude that a surrogate taxa approach, i.e. the use of well-known taxonomic groups (e.g. vascular plants), may indeed deliver good results for capturing total, but less so for threatened, Orthoptera species richness in semi-natural grassland remnants. Small scale habitat diversity may be crucial to allow for the co-existence of a large number of Orthoptera species and has to be taken equally into account as patch size in nature conservation.