Local and landscape responses of biodiversity in calcareous grasslands

Across Europe, calcareous grasslands become increasingly fragmented and their quality deteriorates through abandonment and land use intensification, both affecting biodiversity. Here, we investigated local and landscape effects on diversity patterns of several taxonomic groups in a landscape of highly fragmented calcareous grassland remnants. We surveyed 31 grassland fragments near Göttingen, Germany, in spring and summer 2017 for vascular plants, butterflies and birds, with sampling effort adapted to fragment area. Through regression modelling, we tested relationships between species richness and fragment size (from 314 to 51,395 m2), successional stage, habitat connectivity and the per cent cover of arable land in the landscape at several radii. We detected 283 plant species, 53 butterfly species and 70 bird species. Of these, 59 plant species, 19 butterfly species and 9 bird species were grassland specialists. Larger fragments supported twice the species richness of plants than small ones, and hosted more species of butterflies, but not of birds. Larger grassland fragments contained more grassland specialist plants, but not butterfly or bird specialists. Increasing amounts of arable land in the landscape from 20 to 90% was related to the loss of a third of species of plants, and less so, of butterflies, but not of birds. Per cent cover of arable land negatively correlated to richness of grassland specialist plants and butterflies, but positively to grassland specialist birds. We found no effect by successional stages and habitat connectivity. Our multi-taxa approach highlights the need for conservation management at the local scale, complemented by measures at the landscape scale.

A multitaxa assessment of the effectiveness of agri-environmental schemes for biodiversity management

Agri-environmental schemes (AES) aim to restore biodiversity and biodiversity-mediated ecosystem services in landscapes impoverished by modern agriculture. However, a systematic, empirical evaluation of different AES types across multiple taxa and functional groups is missing. Within one orthogonal design, we studied sown flowering AES types with different temporal continuity, size, and landscape context and used calcareous grasslands as seminatural reference habitat. We measured species richness of 12 taxonomic groups (vascular plants, cicadas, orthopterans, bees, butterflies, moths, hoverflies, flower visiting beetles, parasitoid wasps, carabid beetles, staphylinid beetles, and birds) representing 5 trophic levels. A total of 54,955 specimens were identified using traditional taxonomic methods, and bulk arthropod samples were identified through DNA metabarcoding, resulting in a total of 1,077 and 2,110 taxa, respectively. Species richness of most taxonomic groups, as well as multidiversity and richness of pollinators, increased with temporal continuity of AES types. Some groups responded to size and landscape context, but multidiversity and richness of pollinators and natural enemies were not affected. AES flowering fields supported different species assemblages than calcareous grasslands, but assemblages became more similar to those in seminatural grasslands with increasing temporal continuity. Our results indicate that AES flowering fields and seminatural grasslands function synergistically. Flowering fields support biodiversity even when they are relatively small and in landscapes with few remaining seminatural habitats. We therefore recommend a network of smaller, temporally continuous AES flowering fields of different ages, combined with permanent seminatural grasslands, to maximize benefits for biodiversity conservation and ecosystem service delivery in agricultural landscapes.

Surrounding landscape structures, rather than habitat age, drive genetic variation of typical calcareous grassland plant species

Context Land use change reduced calcareous grasslands throughout Europe during the last decades. Subsequent fragmentation and habitat deterioration led, moreover, to a massive biodiversity decline. To counteract this alarming development, a clear understanding of genetic variation patterns, as fundamental level of biodiversity, becomes inevitable. Objectives The aim of our study was to identify the drivers of genetic variation in common calcareous grassland plant species. More specifically, we tested whether genetic diversity or differentiation of Asperula cynanchica, Campanula rotundifolia, and Linum catharticum depend on habitat age, landscape structure, habitat quality, and/or population size. Methods We investigated 912 individuals, 304 per study species, from 19 calcareous grasslands across the Swabian Alb in Baden-Württemberg (Germany) using AFLP analyses. Results We observed no significant influence of habitat age on genetic diversity and differentiation. Habitat quality also had no impact on genetic diversity and population size only showed weak effects. However, genetic diversity strongly depended on landscape structure represented by distance to the nearest settlement, total area of surrounding calcareous grasslands, and their connectivity. Conclusions Migratory sheep herding is considered as main land use in calcareous grasslands on the Swabian Alb and thus, landscape structures in the study region may describe movement patterns of grazing livestock. In this study, genetic variation in calcareous grassland populations was strongly affected by surrounding landscape structures and subsequent grazing patterns. Therefore, we assume that moderate grazing intensities over the long term may increase levels of genetic diversity, whereas periods of overgrazing or abandonment could lower genetic diversity.

Changes in the Diversity of Dry Calcareous Grasslands After Abandonment of Traditional Management in Devínska Kobyla National Nature Reserve (Southwestern Slovakia, Central Europe)

This study is focused on the evaluation of the values of the diversity indices of semi-natural dry calcareous grasslands of the Festuco-Brometea class in the area of Devínska Kobyla National Nature Reserve 50 years after abandonment of traditional management (grazing and mowing). The values of the species richness, the Shannon–Wiener index of diversity, the Simpson index, and Pielou’s measure of species evenness in the communities in the old and recent data, and the values of the environmental variables based on the Ellenberg indicator values of species were analyzed. For most of these analyses, we used Kruskal–Wallis in R 3.5.1. Compared to the past, we have recorded a significant lower values of the species richness, biodiversity, and species evenness in some communities. In some communities, no significant changes were recorded. Only in one community—Poo badensis-Festucetum pallentis, the higher values of Shannon–Wiener index was recorded compared to the past. The analysis of the Ellenberg indicator values revealed a statistically significant higher Ellenberg indicator values for moisture and nutrients and lower values for light in more recent period compared to the old period. The recorded results could be caused by the changes in the management after the year 1965, after abandonment of grazing and the gradual overgrowing by woody species took place in the area. The frequency of occurrence of some woody species (e.g., Populus alba, P. nigra, and Robinia pseudoacacia) in some communities increased compared to the past.