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Climate change and nitrogen (N) deposition are among the most important drivers of biodiversity change at a global scale. Although commonly considered separately in applied research, conservation, and policy development, both empirical evidence and modelling studies indicate that these two stressors may act synergistically and trigger a more pronounced biodiversity loss than each of them alone. Interactive effects thus need to be considered in biodiversity conservation. In this study, we propose a new method for jointly assessing risk from both stressors to habitats by combining climate envelope modelling and the evaluation of exceedance of empirical critical loads for eutrophication through N deposition. Based on this approach we can calculate a combined risk metric, which is the scaled exceedance of the N critical load and climatic thresholds in the three-dimensional space of N deposition, temperature, and water limitation. We use a habitat map to project this risk metric for 34 EUNIS habitat types across Austria. Resulting risk maps indicated that about 16 % of the area of these natural and semi-natural habitat types is currently at risk from either N exceedance, drought or warming. Using combinations of future climatic (RCP2.5 and RCP8.5) and N deposition (business as usual, current legislation and maximum feasible reduction) scenarios, we predict that the area at risk might increase to up to 19% until 2050, with risk from N-deposition decreasing and risk from climate change increasing. Combined impacts of both stressors affect only up to 2% of the entire evaluated area, but are much more frequent in particular habitat types such as oligotrophic bogs and subalpine to alpine grasslands. We conclude that this method provides a useful screening procedure to identify and compare areas and habitats under combined risk from both stressors and to thus support prioritization and decision making in biodiversity conservation.

There is growing interest in the application of plant functional trait-based approaches for development of sustainable land-use strategies. In this context, one crucial task is to identify and measure plant traits, which respond to land-use intensity (response traits) and simultaneously have an impact on ecosystem functions (effect traits). We hypothesized that species-specific leaf chemical composition, which may function both as response and effect trait, can be derived from Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy tools in combination with multivariate statistical methods We investigated leaf ATR-FTIR spectra of two grasses, Poa pratensis L. and Dactylis glomerata L., and one forb, Achillea millefolium L. collected in grassland plots along a land-use intensity gradient in three regions of Germany. ATR-FTIR spectra appear to function as biochemical fingerprints unique to each species. The spectral response to land-use intensity was not consistent among species and less apparent in the two grasses than in the forb species. Whereas land-use intensification enhanced protein and cellulose content in A. millefolium , giving rise to changes in six spectral bands in the frequency range of 1088–1699 cm −1 , only cellulose content increased in D. glomerata , affecting the bands of 1385–1394 cm −1 . Poa pratensis spectra exhibited minimal changes under the influence of land-use, only in the spectral bands of 1373–1375 cm −1 associated with suberin-like aliphatic compounds. Our findings suggest that some species’ leaf chemical composition is responsive to land-use intensity, and thus, may have a predictive value for ecosystem services provided by those species within grassland vegetation (i.e., herbage yield quality).