Landscape and pollinator responses to lowland fen peatland rewetting: effects of land management, spatial extent, and configuration in the Upper Rhinluch, Germany

Abstract Context Large-scale rewetting of lowland fen peatlands is promoted as a nature-based solution for reducing greenhouse gas emissions from agriculture. The resulting changes in land management and vegetation composition may modify landscape structure, with unknown implications for biodiversity and ecosystem services such as pollination. Objectives We examined multiple scenarios representing different land management types (either Phalaris arundinacea -based paludiculture or abandoned rewetted fen), spatial extents, and spatial configurations of rewetting. We assessed how these scenarios affected landscape heterogeneity and the potential abundance of four wild pollinator guilds: bumblebees, mining bees, hoverflies, and butterflies. Methods Using empirical vegetation surveys, high-resolution land-use maps, and expert-based assessments, we simulated rewetting scenarios with the InVEST model for the Upper Rhinluch in Brandenburg, Germany. Results The spatial extent of rewetted areas, rather than their configuration or post-rewetting land management, was the primary driver of landscape and pollination responses. Greater rewetting extent increased compositional heterogeneity, slightly decreased configurational heterogeneity, but markedly reduced landscape connectivity and potential abundance of all studied guilds. These declines reflected spatial clustering of areas suitable for rewetting, the replacement of hay grasslands by wetland vegetation dominated by tall helophytes and graminoids, which are predominantly wind-pollinated and provide few floral resources for pollinators, and the loss of nesting opportunities for soil-nesting species due to waterlogging. Conclusions Rewetting of lowland fen peatlands may alter landscape structure and reduce pollination potential, although responses may differ in more heterogeneous peatland systems. Targeted floral enrichment and adaptive management will be necessary to sustain pollinator populations and ecosystem services during and after rewetting.