DOI: 10.25829/bexis.25786-1.3.11
title: Arthropod data from 150 grassland plots, 2008-2017, and 140 forest plots, 2008-2016, used in "Arthropod decline in grasslands and forests is associated with drivers at landscape level", Nature

description: To disentangle local and landscape-level effects of land use on the temporal trends of arthropod communities in grasslands and forests, arthropod data were collected annually during the growing period from 2008 to 2017 by standardized sampling at 150 grassland plots and from 2008 to 2016 at 30 forest plots. An additional 118 forest plots were sampled in 2008, 2011 and 2014 to test the overall trend across a larger number of plots. Both grassland and forest plots cover gradients in local land-use intensity. Land-use intensity was quantified in the form of compound indices based on grazing, mowing and fertilization intensity in grasslands (LUI), and on recent biomass removal, the proportion of non-native tree species and deadwood origin in forests (ForMI). To analyze landscape-level effects, we quantified the cover of arable fields and grassland within 1500m radius around each sampling plot (based on ATKIS DLM). We modelled temporal trends in biomass, abundance and species number of arthropods and of different dispersal and trophic guilds separately for grasslands and forests, and tested for effects of local and landscape-scale land-use intensity on these trends, accounting for weather conditions and different spatial scales.
description: Theory: The sample unit is the arthropod community of a grassland or forest plot within a given year. It is characterized by measures of biomass, abundance and species number. A sample unit is considered to represent arthropod populations at our study sites which measured 50m x 50m in grasslands and 100m x 100m in forests. Data from different months and traps per plot were pooled per plot and year.|Measurements Type: Grassland: arthropod density along a 150m transect Forest: activity density of arthropods per plot |instruments: Grassland: sweep net Forest: flight interception trap|procedures: Grassland: All arthropods of the herb layer were sampled twice per year in June and August to represent different phenological windows within the peak season of adult arthropod activity. Based on monthly samplings at the beginning of the study, we identified these two months to represent the best trade-off between reducing sampling effort and covering most species. Arthropods were sampled by sweep netting along a 150-m long transect comprising three of the virtual borders of a site by conducting 60 double sweeps per site. Sweep netting was only conducted on days without rain, low wind speed and after morning dew had dried. Forest: Flying insects were sampled using two flight-interception traps per site located close to two randomly selected corners of each site. Traps consisted of two crossed transparent plastic shields (40 cm x 60 cm) with funnels opening into sampling jars below and above that were filled with 3% CuSO4 solution and a drop of detergent. Traps were operated from March to October and emptied monthly. All samples were sorted to order level in the lab and all groups for which taxonomists were available were identified to species level: grasslands – Araneae, Coleoptera, Hemiptera (Heteroptera and Auchenorrhyncha), Orthoptera; forests – Coleoptera, Hemiptera (Heteroptera). |