Cessation of grazing causes biodiversity loss and homogenization of soil food webs.

There is widespread concern that cessation of grazing in historically grazed ecosystems is causing biotic homogenization and biodiversity loss. We used 12 montane grassland sites along an 800 km north-south gradient across the UK, to test whether cessation of grazing affects local α- and ß-diversity of below-ground food webs. We show cessation of grazing leads to strongly decreased α-diversity of most groups of soil microbes and fauna, particularly of relatively rare taxa. By contrast, the ß-diversity varied between groups of soil organisms. While most soil microbial communities exhibited increased homogenization after cessation of grazing, we observed decreased homogenization for soil fauna after cessation of grazing. Overall, our results indicate that exclusion of domesticated herbivores from historically grazed montane grasslands has far-ranging negative consequences for diversity of below-ground food webs. This underscores the importance of grazers for maintaining the diversity of below-ground communities, which play a central role in ecosystem functioning.

The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis.

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control (18 studies) and pollination services (17 studies) in adjacent crops in North America, Europe and New Zealand. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimise floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.

Molecular Identification of Soil Eukaryotes and Focused Approaches Targeting Protist and Faunal Groups Using High-Throughput Metabarcoding.

While until recently the application of high-throughput sequencing approaches has mostly been restricted to bacteria and fungi, these methods have now also become available to less often studied (eukaryotic) groups, such as fauna and protists. Such approaches allow routine diversity screening for large numbers of samples via DNA metabarcoding. Given the enormous taxonomic diversity within the eukaryote tree of life, metabarcoding approaches targeting a single specific DNA region do not allow to discriminate members of all eukaryote clades at high taxonomic resolution. Here, we report on protocols that enable studying the diversity of soil eukaryotes and, at high taxonomic resolution, of individual faunal and protist groups therein using a tiered approach: first, the use of a general eukaryotic primer set targeting a wide range of eukaryotes provides a rough impression on the entire diversity of protists and faunal groups. Second, more focused approaches enable deciphering subsets of soil eukaryotes in higher taxonomic detail. We provide primers and protocols for two examples: soil microarthropods and cercozoan protists.