Species distribution modelling of stream macroinvertebrates under climate change scenarios

There is increasing evidence that climate change will have a severe impact on species’ distributions by altering the climatic conditions within their present ranges. Especially species inhabiting stream ecosystems are expected to be strongly affected due to warming temperatures and changes in precipitation patterns. The aim of this thesis was to investigate how distributions of aquatic insects, i.e., benthic stream macroinvertebrates would be impacted by warming climates. The methods comprised of an ensemble forecasting technique based on species distribution models (SDMs) and climate change scenarios of the Intergovernmental Panel on Climate Change of the year 2080. Future model projections were generated for a wide variety of species from a number of taxonomic orders for two spatial scales: a stream network within the lower mountain ranges of Germany, and the entire territory across Europe. In addition, the effect of the modelling technique on habitat suitability projections was investigated by modifying the choice of study area (continuous area vs. stream network) and the choice of predictors (standard vs. corrected set). Projections of future habitat suitability showed that potential climate-change impacts would be dependent on species’ thermal preferences, and with a similar pattern for both spatial scales. Future habitat suitability was projected to remain for most or all of the modelled species, and species were projected to track their climatically suitable conditions by shifting uphill along the river continuum within the lower mountain ranges, and into a north-easterly direction across Europe. Cold-adapted headwater and high-latitude species were projected to lose suitable habitats, whereas gains would be expected for warm-adapted river and low-latitude species along the river continuum and across Europe, respectively. Additionally, habitat specialist species in terms of endemics of the Iberian Peninsula were identified as potential climate-change losers, highlighting their restricted habitat availability and therefore vulnerability to warming climates. The main findings of this thesis underline the high susceptibility of stream macroinvertebrates to ongoing climate change, and give insights into patterns of possible consequences due to changes in species’ habitat suitability. Concerning the methodology, a clear recommendation can be given for future modelling approaches of stream macroinvertebrates by building models within a stream network and with a careful choice of environmental predictors, to reduce uncertainties and thus to improve model projections

Forest tree seedlings may suffer from predicted future winters

201

Winter in a changing climate affecting the survival of Scots pine seedlings

Poster

Climate model variability leads to uncertain predictions of the future abundance of stream macroinvertebrates

Climate change has the potential to alter the flow regimes of rivers and consequently affect the taxonomic and functional diversity of freshwater organisms. We modeled future flow regimes for the 2050 and 2090 time horizons and tested how flow regimes impact the abundance of 150 macroinvertebrate species and their functional trait compositions in one lowland river catchment (Treene) and one mountainous river catchment (Kinzig) in Europe. We used all 16 global circulation models (GCMs) and regional climate models (RCMs) of the CORDEX dataset under the RCP 8.5 scenario to calculate future river flows. The high variability in relative change of flow among the 16 climate models cascaded into the ecological models and resulted in substantially different predicted abundance values for single species. This variability also cascades into any subsequent analysis of taxonomic or functional freshwater biodiversity. Our results showed that flow alteration effects are different depending on the catchment and the underlying species pool. Documenting such uncertainties provides a basis for the further assessment of potential climate-change impacts on freshwater taxa distributions

Is tree species diversity or tree species identity the most important driver of European forest soil carbon stocks?

201

Tree species richness affecting fine root biomass in European forests

201

Effects of snow condition on microbial respiration of Scots pine needle litter in a boreal forest

201

A high-resolution streamflow and hydrological metrics dataset for ecological modeling using a regression model

Hydrological variables are among the most influential when analyzing or modeling stream ecosystems. However, available hydrological data are often limited in their spatiotemporal scale and resolution for use in ecological applications such as predictive modeling of species distributions. To overcome this limitation, a regression model was applied to a 1 km gridded stream network of Germany to obtain estimated daily stream flow data (m3 s−1) spanning 64 years (1950–2013). The data are used as input to calculate hydrological indices characterizing stream flow regimes. Both temporal and spatial validations were performed. In addition, GLMs using both the calculated and observed hydrological indices were compared, suggesting that the predicted flow data are adequate for use in predictive ecological models. Accordingly, we provide estimated stream flow as well as a set of 53 hydrological metrics at 1 km grid for the stream network of Germany. In addition, we provide an R script where the presented methodology is implemented, that uses globally available data and can be directly applied to any other geographical region