Sagrario Gámez-Virués’s research while affiliated with Fujian Agriculture and Forestry University and other places

Despite a developing understanding of how landscape level processes moderate biodiversity patterns and ecosystem functioning, key questions remain unresolved, therefore limiting our ability to manage for biodiversity conservation and ecosystem functioning at the most appropriate scales. These questions have remained unanswered because studies in agricultural landscapes generally over-emphasize alpha diversity within managed land uses, and are focused at scales that are irrelevant to species studied. We argue that the key to resolving unanswered questions in landscape-moderated effects on biodiversity and ecosystem functioning lies in establishing the distribution of available species and functions across the landscape and between land uses, and in understanding how this distribution of species varies with changing landscape context. We emphasize the need for studies that empirically test the mechanisms underpinning landscape-moderated effects on biodiversity and ecosystem function and link these with ecosystem service delivery. We facilitate this approach by outlining the empirical investigations that will lead to a better understanding of biodiversity patterns and ecosystem functioning at the landscape scale, and we highlight statistical approaches to support these different approaches to sampling. Our paper is divided in four sections: (A) we identify where and why gaps exist in our mechanistic understanding of landscape level processes, by reviewing current hypotheses; (B) we outline why, and how, landscape level research would benefit from shifting the focus to the distribution and partitioning of species and functions within a landscape; (C) we outline why, and how, larger scale processes, such as dispersal and meta-population dynamics need to be addressed in a more interactive fashion; and finally, (D) we round out by highlighting the experimental settings where landscape effects most urgently need testing.

Ecological studies are increasingly moving towards trait-based approaches, as the evidence mounts that functions, as opposed to taxonomy, drive ecosystem service delivery. Among ecosystem services, biological control has been somewhat overlooked in functional ecological studies. This is surprising given that, over recent decades, much of biological control research has been focused on identifying the multiple characteristics (traits) of species that influence trophic interactions. These traits are especially well developed for interactions between arthropods and flowers – important for biological control, as floral resources can provide natural enemies with nutritional supplements, which can dramatically increase biological control efficiency. Traits that underpin the biological control potential of a community and that drive the response of arthropods to environmental filters, from local to landscape-level conditions, are also emerging from recent empirical studies. We present an overview of the traits that have been identified to (i) drive trophic interactions, especially between plants and biological control agents through determining access to floral resources and enhancing longevity and fecundity of natural enemies, (ii) affect the biological control services provided by arthropods, and (iii) limit the response of arthropods to environmental filters, ranging from local management practices to landscape-level simplification. We use this review as a platform to outline opportunities and guidelines for future trait-based studies focused on the enhancement of biological control services.

Biodiversity loss can affect the viability of ecosystems by decreasing the ability of communities to respond to environmental change and disturbances. Agricultural intensification is a major driver of biodiversity loss and has multiple components operating at different spatial scales: from in-field management intensity to landscape-scale simplification. Here we show that landscape-level effects dominate functional community composition and can even buffer the effects of in-field management intensification on functional homogenization, and that animal communities in real-world managed landscapes show a unified response (across orders and guilds) to both landscape-scale simplification and in-field intensification. Adults and larvae with specialized feeding habits, species with shorter activity periods and relatively small body sizes are selected against in simplified landscapes with intense in-field management. Our results demonstrate that the diversity of land cover types at the landscape scale is critical for maintaining communities, which are functionally diverse, even in landscapes where in-field management intensity is high.

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.

Biodiversity in agroecosystems is affected by human management practices at both the local and at the landscape‐levels (e.g., reduction of landscape heterogeneity via homogenisation of land‐uses). While local land use intensity is easier to measure in terms of fertiliser and pesticide application, grazing and mowing, landscape heterogeneity metrics are more difficult to obtain and are still at an early stage of development. To date, landscape heterogeneity has most‐commonly been defined as the diversity of human land uses within a landscape (structural heterogeneity) and not in terms of habitat‐ or resource‐requirements of animals (functional heterogeneity). While some species require quite specific resources or specific combinations of resources for different life‐stages, others are freed from such ecological constraints and can readily utilise a wide range of habitats. Thus, by considering land uses in terms of the functional value that they represent for species (and not simply from a human land use perspective) we can expect to have a more accurate understanding of effects of landscape heterogeneity on species, functional groups and communities. We examined the effects of landscape heterogeneity on community composition for Lepidoptera collected in the German Biodiversity Exploratories project. Further, we analysed the effects of landscape heterogeneity on the diversity of functional groups defined by traits representing habitat‐and feeding‐specialisation and dispersal ability. We report on how these different metrics of landscape heterogeneity relate to the functional diversity within the community. For example, preliminary results indicate that landscapes with decreased levels of structural heterogeneity select against smaller, less agile lepidopteran species. These findings may guide management practices for conservation of lepidopteran functional diversity in managed grasslands.

IntroductionLandscape Ecology and Pest ManagementLandscape Complexity and Biological ControlMechanisms Behind Landscape EffectsSpatial Scales of Landscape EffectsHabitat Manipulations to Improve Biological Control: Attempts to Place the Right Diversity at the Right Spatial ScaleConclusion AcknowledgementsReferences

Shelterbelts have become a refuge and source of food for wildlife because of habitat loss in farmlands. However, effects of shelterbelt attributes such as plant diversity and habitat structure on different trophic levels within shelterbelts are unclear. Effects of shelterbelt woody plant diversity and habitat structure (lower vegetation strata, logs, litter and rocks) were measured on the growth and herbivory of Eucalyptus blakelyi saplings that were caged from birds, caged from birds and arthropods and un-caged. Arthropod diversity of E. blakelyi saplings and shelterbelts was evaluated. Height and stem diameter of saplings in all treatments was positively correlated with plant diversity. Habitat structure was negatively correlated with numbers of leaves on E. blakelyi saplings and positively correlated with herbivory, which was greater in saplings caged from birds. The overall abundance of arthropods inhabiting shelterbelts correlated positively with plant diversity, but negatively with habitat structure. Araneae and Formicidae were the most common taxa on E. blakelyi saplings and were more numerous on saplings caged from birds, suggesting an important role of these vertebrates as predators of shelterbelt arthropods.

Significant worldwide interest in conservation biological control in agricultural systems currently exists but little information is available on the usefulness of this approach in farm forestry. In a field experiment conducted in a native vegetated shelterbelt in central-west New South Wales, we measured the diversity of wasps in plots comprising Eucalyptus blakelyi Maiden (Myrtaceae) trees with and without a groundcover of Lobularia maritima (L.) Desv. (Brassicaceae). Vacuum samples revealed a greater abundance and species richness of parasitic wasps in the plots comprising trees surrounded by the L. maritima groundcover. Cotesia sp. (Hymenoptera: Braconidae), Pteromalus sp. (Hymenoptera: Pteromalidae), Anagyrus sp. (Hymenoptera: Encyrtidae), Entedoninae sp. and Eulophidae sp. 1 (Hymenoptera: Eulophidae) were the most common taxa. These were more abundant also in the trees with the L. maritima groundcover. Ardozyga stratifera (Meyrick) (Lepidoptera: Gelechiidae) larvae, that were naturally infesting the E. blakelyi trees, were significantly more parasitized in the trees with the L. maritima groundcover. Results indicate that parasitic wasps associated with a native-tree shelterbelt in Australia were amenable to manipulation via groundcover vegetation.

Abstract The value of insectivorous birds as agents for biological control of arthropod pests has been little studied, especially in Australia. This paper reports on the extent to which arthropods from various pest and non-pest taxa feature in the diets of birds captured in farm shelterbelts in central western New South Wales. The parameters examined were the types of arthropod fragments in bird faeces and percentage volume and frequency of occurrence of each component. The faecal data were compared with samples of the arthropod fauna trapped in shelterbelts during the period the birds were captured. In 26 of 29 faecal samples, arthropod fragments were the predominant components, the most common being from Coleoptera, Hymenoptera (especially Formicidae), Orthoptera and Araneae. The recognisable pest taxa in faecal samples were Scarabaeidae and wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae). The results indicate that the native bird species common in farm shelterbelts preyed on a range of arthropod taxa including several that are pests of crops and pastures. Accordingly, conservation of birds in farmlands could contribute to suppression of arthropod pests.