Biology subjects

Grescho, V.

Publications and source records attributed to Grescho, V..

3 recordsLinked to original sources

bioRxiv2023

The majority of Germany's small agricultural streams are in poor ecological status

Agricultural pesticides, nutrients, and habitat degradation are major causes of insect declines in lowland streams. To effectively conserve and restore stream habitats, standardized stream monitoring data and societal support for freshwater protection are needed. Here, we sampled 137 small stream sites across Germany, 83% of which were located in agricultural catchments, with more than 900 citizen scientists in 96 monitoring groups. Sampling was carried out according to Water Framework Directive standards as part of the citizen science freshwater monitoring program FLOW in spring and summer 2021, 2022 and 2023. The biological indicator SPEARpesticides was used to assess pesticide exposure and effects based on benthic invertebrate community composition. Overall, 58% of the monitored agricultural stream sites did not achieve a good ecological status in terms of macroinvertebrate community composition and indicated high pesticide exposure (SPEARpesticides status class: 29% moderate, 19% poor, 11% bad). The indicated pesticide pressure in streams was related to the proportion of agricultural land in the catchment area (R2=0.23, p<0.001). With regards to hydromorphology, monitoring results revealed that 65% of the agricultural stream sites failed to reach a good status. The data base produced by citizen science groups was characterized by a high degree of accuracy. This was quantified by a comparative survey of SPEARpesticides index (R2=0.79, p<0.001) and hydromorphology index values (R2=0.72, p<0.001) by citizen scientists and professionals. Such citizen-driven monitoring of the status of watercourses could play a crucial role in monitoring and implementing the objective of the European Water Framework Directive, thus contributing to restoring and protecting freshwater ecosystems. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=82 SRC="FIGDIR/small/564349v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1bbc51aorg.highwire.dtl.DTLVardef@896431org.highwire.dtl.DTLVardef@10e0bborg.highwire.dtl.DTLVardef@121819_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Assessment of ecological status of small agricultural streams in Germany - Pesticides affected invertebrates (bioindicator SPEAR) in 58% of agricultural streams - Failure to reach good hydromorphological status in 65% of agricultural streams - Citizen science monitoring achieves high data accuracy - Citizen science can support European Water Framework Directive monitoring

ecology↗

bioRxiv2020

Contrasting impacts of urban and farmland cover on flying insect biomass

Recent studies report declines in biomass, abundance and diversity of terrestrial insect groups. While anthropogenic land use is one likely contributor to this decline, studies assessing land cover as a driver of insect dynamics are rare and mostly restricted in spatial scale and types of land cover. In this study, we used rooftop-mounted car nets in a citizen science project ( InsectMobile) to allow for large-scale geographic sampling of flying insects across Denmark and parts of Germany. Citizen scientists sampled insects along 278 10 km routes in urban, farmland and semi-natural (grassland, wetland and forest) landscapes in the summer of 2018. We assessed the importance of local to landscape-scale effects and land use intensity by relating insect biomass to land cover in buffers of 50, 250, 500 and 1000 m along the routes. We found a negative association of urban cover and a positive association of farmland on insect biomass at a landscape-scale (1000 m buffer) in both countries. In Denmark, we also found positive effects of all semi-natural land covers, i.e. grassland (largest at the landscape-scale, 1000 m), forests (largest at intermediate scales, 250 m), and wetlands (largest at the local-scale, 50 m). The negative association of insect biomass with urban land cover and positive association with farmland were not clearly modified by any variable associated with land use intensity. Our results show that land cover has an impact on flying insect biomass with the magnitude of this effect varying across spatial scales. Since we consistently found negative effects of urban land cover, our findings highlight the need for the conservation of semi-natural areas, such as wetlands, grasslands and forests, in Europe.

ecology↗

bioRxiv2020

Widespread decline in plant diversity across six decades

Based on plant occurrence data covering all parts of Germany, we investigated changes in the distribution of 2146 plant species between 1960 and 2017. We analyzed 29 million occurrence records over an area of [~]350.000 km2 on a 5 x 5 km grid using temporal and spatio-temporal models and accounting for sampling bias. Since the 1960s, more than 70% of investigated plant species showed significant declines in nation-wide occurrence. Archaeophytes (species introduced before 1492) most strongly declined but also native plant species experienced severe declines. In contrast, neophytes (species introduced after 1492) increased in their nation-wide occurrence but not homogeneously throughout the country. Our analysis suggests that the strongest declines in native species already happened in the 1960s-80s, a time frame in which usually few data exist. Increases in neophytic species were strongest in the 1990s and 2010s. Overall, the increase in neophytes did not compensate for the loss of other species, resulting in a decrease in mean grid-cell species-richness of -1.9% per decade. The decline in plant biodiversity is a widespread phenomenon occurring in different habitats and geographic regions. It is likely that this decline has major repercussions on ecosystem functioning and overall biodiversity, potentially with cascading effects across trophic levels. The approach used in this study is transferable to large-scale trend analyses using heterogeneous occurrence data.

ecology↗