Verlässliche Daten über unsere Lebens­grundlage

Als Folge des Klimawandels etablieren sich immer mehr wärmeliebende Arten in Schweizer Gewässern. Da wirbellose Kleinlebewesen als Bioindikatoren für die Qualität von Fliessgewässern dienen, könnte diese Entwicklung die biologische Gewässerbeurteilung verfälschen. Simulationen zeigen, dass die Vielfalt der Wirbellosen tatsächlich zunehmen wird, jedoch auf Kosten kälteliebender Arten. Soweit sich das beurteilen lässt, sind die verwendeten Indizes aber robust genug, um ihre Aussagekraft zur Gewässerqualität für die nächsten Jahrzehnte zu behalten.

Vorburger, C., Khaliq, I., Ramampiandra, E. C., Narwani, A., & Schuwirth, N. (2024). Biologische Gewässerbeurteilung im Klimawandel. Aqua & Gas, 104(10), 60-65.

Die Gewässerstruktur und Wasserqualität der Schweizer Fliessgewässer sollen durch Bestimmungen des Gewässerschutzgesetzes verbessert werden. Langzeitdaten der beiden schweizweiten Monitoringprogramme NAWA und BDM zeigen, dass bereits gewisse Auswirkungen auf die Makroinvertebraten zu erkennen sind.

Steiner, E., Martinez, N., Thoma, M. & Ilg, C. (2024). Auswirkungen sichtbarer Veränderungen an Gewässermessstellen. Analyse von Makroinventebraten-Daten. Aqua & Gas N° 7+8: 80-85.

Pollution, climate change, and shrinking habitats are driving major changes in flowering plant and pollinator populations. These include shifts in local abundance, population extirpations, range shifts, altered community composition, and reshuffled interactions. To date, evidence for these changes mostly reflect opportunistic efforts to collect occurrence data to document distributions. Coarse-scale perspectives on biodiversity change can be invaluable, especially when threats to rare habitats are widely distributed, but many changes occur slowly (decades) at such scales. Opportunistic occurrence data are therefore generally less useful for detecting short-term trends and monitoring the effectiveness of conservation policies. They are also typically biased for large-scale surveillance monitoring (Boyd et al., 2022) and rarely encompass both plants and pollinators, limiting our ability to estimate broad and fine-scale trends in populations and plant–pollinator interactions. Ecologists often prefer using plot-based methods for systematic surveys and monitoring, as these provide quantitative data on abundance and distributions. Resurveying such plots adds a time dimension, greatly enriching our understanding of how species abundances and distributions shift in response to drivers of global change. Monitoring and resurvey data remain scarce, leaving pictures of ecological conditions and change uncertain. Except for Switzerland and the UK, countries are slow to support systematic programs to monitor plants and pollinators.

The 23–24 May Paris symposium on ‘New solutions to monitor plants, pollinators and their interactions in a changing world’ brought scientists together to assess the state of plant and pollinator monitoring schemes in Europe and to ponder how these might be improved, extended, and coordinated (https://www.college-de-france.fr/fr/agenda/colloque/nouvelles-approches-pour-le-suivi-des-plantes-des-pollinisateurs-et-de-leurs-interactions-dans-un). This group met to review existing schemes, compare the trends and indicators they produce, and outline future needs for research and policy. These needs include expanding the number of plots, species and habitats monitored, the different methods (e.g. by citizen scientists) and how frequently they are surveyed; how to identify and locate plants and insects quickly and reliably (including new technologies); how best to coordinate plant and pollinator sampling; and statistical tools to integrate heterogeneous data and infer causal relationships.

Porcher, E., Bonnet, P., Damgaard, C., De Frenne, P., Deguines, N., Ehlers, B.K., Frei, J., García, M.B., Gros, C., Jandt, U., Joly, A., Martin, G., Michez, D., Pescott, O.L., Roth, T. and Waller, D. (2024). Can we harmonize the monitoring of plants and pollinators?. New Phytol, 244: 39-42. https://doi.org/10.1111/nph.20038

The negative effects of habitat loss on biodiversity are undisputed, while the effect of habitat configuration, i.e., the spatial arrangement of habitat area, has been debated for decades. To develop a more comprehensive understanding, it is important to know when and how configuration matters. In this study, we tested whether forest configuration influences the richness of species in groups characterized by varying shade tolerance in different ways and how such effects are related to habitat amount (i.e., the percentage of forest cover) at the landscape scale. Based on 104 survey plots (each measuring 1 km²) of vascular plants on the Swiss Plateau, and using two statistical approaches (i.e., multiple regression and path analysis), we modeled the effects of habitat amount and configuration (measured as number of forest patches, total edge length, and proximity index) across all the plots and separately for three habitat amount classes: <10%, 10%–30%, and >30% forest cover. When we modeled all plots together, we found that, after controlling for habitat amount, the forest configuration significantly affected species richness. When we considered the different habitat amount classes separately, most of the significant effects of habitat configuration on species richness occurred only for habitat amounts of <10% forest cover. Additionally, the response to forest configuration differed among species with different shade tolerances. When forest area was <10%, the effects of the number of patches and the total edge length on the species richness of light-demanding forest species were greater than the effect of habitat amount, whereas neither configuration metric affected the richness of shade-tolerant species. In conclusion, our findings highlight the importance of configuration in landscapes with a small amount of habitat. At the same time, they demonstrate that considering the confounding factors (e.g. species traits) is important for  understanding the effects of forest configuration on biodiversity and that generalizations remain a challenge for landscape ecology.

Pan, Y., Hersperger, A. M., Ge, G., & Nobis, M. P. (2024). Effects of habitat configuration on biodiversity along gradients of forest cover on the Swiss Plateau. Forest Ecosystems, 11, 100223. https://doi.org/10.1016/j.fecs.2024.100223