Search

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.

1.Rapid growth of the world's human population has increased pressure on landscapes to deliver high levels of multiple ecosystem services, including food and fibre production, carbon storage, biodiversity conservation and recreation. However, we currently lack general principles describing how to achieve this landscape multifunctionality. 2.We combine theoretical simulations and empirical data on 14 ecosystem services measured across 150 grasslands in three German regions. In doing so, we investigate the circumstances under which spatial heterogeneity in a driver of ecosystem functioning (an ‘ecosystem‐driver,’ e.g. the presence of keystone species, land‐use intensification or habitat types) increases landscape‐level ecosystem multifunctionality. 3.Simulations based on theoretical data demonstrated that relationships between heterogeneity and landscape multifunctionality are highly variable and can range from non‐significant to strongly positive. Despite this variability, we could identify criteria under which heterogeneity‐landscape multifunctionality relationships were most strongly positive: this happened when multiple ecosystem services responded contrastingly (both positively and negatively) to an ecosystem‐driver. 4.These findings were confirmed using empirical data, which showed that heterogeneity in land‐use intensity promoted landscape multifunctionality in cases where functions with both positive (e.g. plant biomass) and negative (e.g. flower cover) responses to land use intensification were included. For example, the simultaneous provisioning of ecosystem functions related to forage production (generally profiting from land‐use intensification), biodiversity conservation and recreation (generally decreasing with land‐use intensification) was highest in landscapes consisting of sites varying in land‐use intensity. 5.Synthesis and applications. Our findings show that there are general principles governing landscape multifunctionality. A knowledge of these principles may support land management decisions. For example, knowledge of relationships between ecosystem services and their drivers, such as land use type, can help estimate the consequences of increasing or decreasing heterogeneity for landscape‐level ecosystem service supply, although interactions between landscape units (e.g. the movement of pollinators) must also be considered.

Summary Landscape heterogeneity represents two aspects of landscape simplification: (i) compositional heterogeneity (diversity of habitat types); and (ii) configurational heterogeneity (number, size and arrangement of habitat patches), both with different ecological implications for community composition. We examined how independent gradients of compositional and configurational landscape heterogeneity, at eight spatial scales, shape taxonomic and functional composition of butterfly communities in 91 managed grasslands across Germany. We used landscape metrics that were calculated from functional maps based on habitat preferences of individual species during different life stages. The relative effects of compositional and configurational landscape heterogeneity were compared with those of local land-use intensity on butterfly taxonomic diversity, community composition and functional diversity of traits related to body size, feeding breadth and migratory tendency. As expected, compositional heterogeneity had strong positive effects on taxonomic diversity, while configurational heterogeneity had strong positive effects on trait dominance within the community. When landscapes had smaller mean patch size and greater boundary area, communities were dominated by species with more specialized larval feeding, decreased forewing length and limited migratory tendency. The positive effects of increased configurational landscape heterogeneity outweighed the negative effects of local land-use intensity on larval-feeding specialization, at all spatial scales, highlighting its importance for specialists of all dispersal capabilities. Synthesis and applications. We show that landscapes with high compositional heterogeneity support communities with greater taxonomic diversity, while landscapes with high configurational heterogeneity support communities that include vulnerable species (feeding specialists with larger body size, sedentary nature and more negatively affected by local management intensity). A decline in functional community composition can lead to functional homogenization, affecting the viability of the ecosystems by decreasing the variability in their responses to disturbance and altering their functioning. A landscape management for grasslands that promotes the maintenance of small patch sizes and a diversity of land uses in the surrounding landscape (within 250–1000 m) is recommended for the conservation of diverse butterfly communities. These strategies could also benefit government programmes such as the EU 2020 Biodiversity Strategy in their efforts to reduce the loss of biodiversity 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.

Global change, especially land‐use intensification, affects human well‐being by impacting the delivery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is a major component of global change effects on multifunctionality in real‐world ecosystems, as in experimental ones, remains unclear. Therefore, we assessed biodiversity, functional composition and 14 ecosystem services on 150 agricultural grasslands differing in land‐use intensity. We also introduce five multifunctionality measures in which ecosystem services were weighted according to realistic land‐use objectives. We found that indirect land‐use effects, i.e. those mediated by biodiversity loss and by changes to functional composition, were as strong as direct effects on average. Their strength varied with land‐use objectives and regional context. Biodiversity loss explained indirect effects in a region of intermediate productivity and was most damaging when land‐use objectives favoured supporting and cultural services. In contrast, functional composition shifts, towards fast‐growing plant species, strongly increased provisioning services in more inherently unproductive grasslands.

Although temporal heterogeneity is a well-accepted driver of biodiversity, effects of interannual variation in land-use intensity (LUI) have not been addressed yet. Additionally, responses to land use can differ greatly among different organisms; therefore, overall effects of land-use on total local biodiversity are hardly known. To test for effects of LUI (quantified as the combined intensity of fertilization, grazing, and mowing) and interannual variation in LUI (SD in LUI across time), we introduce a unique measure of whole-ecosystem biodiversity, multidiversity. This synthesizes individual diversity measures across up to 49 taxonomic groups of plants, animals, fungi, and bacteria from 150 grasslands. Multidiversity declined with increasing LUI among grasslands, particularly for rarer species and aboveground organisms, whereas common species and belowground groups were less sensitive. However, a high level of interannual variation in LUI increased overall multidiversity at low LUI and was even more beneficial for rarer species because it slowed the rate at which the multidiversity of rare species declined with increasing LUI. In more intensively managed grasslands, the diversity of rarer species was, on average, 18% of the maximum diversity across all grasslands when LUI was static over time but increased to 31% of the maximum when LUI changed maximally over time. In addition to decreasing overall LUI, we suggest varying LUI across years as a complementary strategy to promote biodiversity conservation.