ADAPTION OF A LAND USE INTENSITY INDEX (LUIS) TO PREDICT RESPONSES OF ECOSYSTEM FUNCTIONING IN STREAMS

Intensive agriculture depends heavily on the application of fertilizers and pesticides to increase crop production. However, export of these substances from agricultural areas into surface waters impairs water bodies’ ecological status and ecosystem functions. Prediction of stream ecosystem functioning from land use information is challenging, as it requires knowledge on how spatially distributed agricultural impacts in the catchment are integrated along the stream network to affect in-stream ecosystem functioning. To address this gap, we introduce a novel Agricultural Land-Use Intensity index for Streams (LUIS), designed to quantify and differentiate the multiple stressors that agricultural land use exerts on stream ecosystems. LUIS integrates grid-level information on fertilizer and pesticide use with hydrological connectivity to assess agricultural stressors at the sub-catchment scale, accounting for long-range impacts. To connect LUIS with trophic transfer efficiency (TTE) as a proxy for ecosystem functioning, we conducted a large sampling campaign in the Harz mountains in Saxony-Anhalt (Germany), across 20 different streams spanning a LUIS gradient. By analyzing the shape of the stressor-response relationship, we aim to reveal potential thresholds in land use intensity where ecosystem functionality may experience abrupt changes, shifting outside sustainable safe operating spaces. This approach provides a quantitative assessment of LUIS-function relationships, highlighting critical points where agricultural pressures could induce significant shifts in ecosystem performance.

Presentation Preference: Oral

Primary Presenter: Alina Kindinger, Helmholtz Centre for Environmental Research - UFZ (alina.kindinger@ufz.de)

Authors:

Alina Kindinger, Helmholtz Centre for Environmental Research - UFZ  (alina.kindinger@ufz.de)

Michael Agyekum, Helmholtz Centre for Environmental Research - UFZ  (michael-kyei.agyekum@ufz.de)

Devanshi Pathak, Deltares, Delft, The Netherlands  (devanshi.pathak@deltares.nl)

Dietrich Borchardt, Helmholtz Centre for Environmental Research - UFZ  (dietrich.borchardt@ufz.de)

Markus Weitere, Helmholtz Centre for Environmental Research - UFZ  (markus.weitere@ufz.de)

Karin Frank, Helmholtz Centre for Environmental Research - UFZ  (karin.frank@ufz.de)

Mechthild Schmitt-Jansen, Helmholtz Centre for Environmental Research - UFZ  (mechthild.schmitt@ufz.de)

Olaf Büttner, Helmholtz Centre for Environmental Research - UFZ  (olaf.buettner@ufz.de)

Ulrike Scharfenberger, Center of Advanced System Understanding, Helmholtz Center for Dresden-Rossendorf  (ulrike.scharfenberger@ufz.de)

Mario Brauns, Helmholtz Centre for Environmental Research - UFZ  (mario.brauns@ufz.de)

Patrick Fink, University of Cologne, Institute for Zoology  (patrick.fink@ufz.de)