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Insect herbivores comprise the majority of macroinvertebrate communities of temperate grasslands and act as drivers for important ecosystem functions. Landscape- and local-level land use may alter species pools and dispersal possibilities and act as local environmental filters, affecting insect trait composition. While environmental filtering by local land use has repeatedly been shown to affect insect community assembly, less is known about the role of land-use intensity at the landscape level. We studied the relative importance of both local- and landscape-level land use in shaping the functional diversity and composition as well as the functional β-diversity among herbivore communities. We used abundance data of three main herbivorous insect groups from grasslands across three regions in Germany and combined it with data on nine morphometric traits related to functions such as dispersal abilities to analyse the effects of different land-use components on community assembly. Land use at both the local and landscape level affected the functional composition of insect communities. Some trait combinations were particularly sensitive to changes in management intensity, whereas others reacted strongly to the availability of suitable habitats in the surrounding area. Simultaneously, functional diversity was not affected by land use at either spatial level. However, increasing local management intensity reduced functional β-diversity. We conclude that both local- and landscape-level land use shape the functional composition of insect communities. Our results highlight the importance of considering land use across multiple spatial scales to understand its effects on the functional integrity of herbivore communities in temperate grasslands.

Intensification of land use is known as a major driver of worldwide decline in biodiversity. Trophic interactions might be especially affected by a changing landscape structure due to agricultural intensification. In this study we investigated the effects of increasing land use intensity on a tritrophic system at different spatial scales in a landscape context. We examined two weevil species, Mecinus labilis Herbst and M. pascuorum Gyllenhal, as well as their common parasitoid, Mesopolobus incultus Walker, living on a common native herb, the ribwort plantain (Plantago lanceolata L.), at 76 sites in three geographic regions in Germany. The effect of land use intensity on species abundances was analysed across a range of spatial scales (100–2000 m) around the study sites. In all three regions and across most spatial scales, an increasing proportion of intensively managed grasslands in the surrounding landscape directly negatively influenced herbivore abundance. An increasing proportion of semi-natural habitats had a direct positive influence on herbivore abundance. The abundance of M. labilis was best explained at radii of r = 1500–2000 m, that of M. pascuorum at r = 100–500 m. The parasitoid, M. incultus, was indirectly influenced by land use intensity via the density of its two hosts. Agricultural intensification of grasslands can profoundly affect the abundance of their herbivorous and entomophagous fauna at landscape scale. This may have important implications for landscape management and the conservation of higher trophic level organisms in agricultural landscapes.

Current biodiversity conservation policies have so far had limited success because they are mainly targeted to the scale of individual fields with little concern on different responses of organism groups at larger spatial scales. We investigated the relative impacts of multi-scale factors, including local land use intensity, landscape context and region, on functional groups of beetles (Coleoptera). In 2008, beetles were suction-sampled from 95 managed grasslands in three regions, ranging from Southern to Northern Germany. The results showed that region was the most important factor affecting the abundance of herbivores and the abundance and species composition of predators and decomposers. Herbivores were not affected by landscape context and land use intensity. The species composition of the predator communities changed with land use intensity, but only in interaction with landscape context. Interestingly, decomposer abundance was negatively related to land use intensity in low-diversity landscapes, whereas in high-diversity landscapes the relation was positive, possibly due to enhanced spillover effects in complex landscapes. We conclude that (i) management at multiple scales, from local sites to landscapes and regions, is essential for managing biodiversity, (ii) beetle predators and decomposers are more affected than herbivores, supporting the hypothesis that higher trophic levels are more sensitive to environmental change, and (iii) sustaining biological control and decomposition services in managed grassland needs a diverse landscape, while effects of local land use intensity may depend on landscape context.