System ecology of legumes mixes in ley production : impact on pollinating insects and further implications for production in northern Sweden

Sammanfattning: The population and diversity of pollinating insects in Europe are declining, partly due to lossof habitat. In agricultural landscapes, farming practices with more intensified land use haveincreased. In Swedish agricultural habitats, most ley production is dominated by grass and red clover (Trifolium pratense). The aim of this thesis is to assess whether a mixture of native legume species (more diverse than normally being used in ley production) can increase biodiversity of pollinating insects and provide better forage in northern Sweden. Several methods to assess increases in biodiversity of pollinating insects were conducted: (1) observational survey, (2) pollen analysis of bee pollen and honey, (3) legume flower pollencount, (4) nitrogen fixation of legume plants, (5) enrichment of microbes and molecular analysis of nectar and root nodules samples from legumes. Statistically significant differences could be found when testing legume flower pollen and observational data. The pollination ecology of legume mixes in ley production incorporates many different factors that could influence biodiversity of pollination insects. Though this thesis did not find statistically strong indications of increase in biodiversity of pollinating insects, further studies with more observational surveys and possible DNA metabarcoding could shed light regarding if increase of biodiversity of pollinating insects is possible or not regarding ley production habitats innorthern Sweden.