| Summary: | The rapid loss of species-rich grasslands in the UK may have profound environmental and socio-economic ramifications. Although they were once the foundation of livestock production systems, the agricultural use of these landscapes has rapidly declined since the 'Green Revolution' of the 1950s due to increased economic incentives to replace species-rich grasslands with agriculturally improved leys and arable fields. In this thesis, I examined the agricultural value of species-rich grasslands in lowland England and the potential ecological impact of losing these landscapes. My research had four main objectives: (1) to determine whether the nutritional composition of forage from species-rich grasslands was comparable to commercial livestock feeds, (2) to assess the bioenergy output of biomass from species-rich grasslands compared to current bioenergy feedstocks, (3) to determine the effect of land use change and agricultural intensification on microbial diversity, and (4) to determine whether grassland biodiversity was stable or changed (temporally and spatially) over time. I show that the forage quality of species-rich grasslands is comparable to that of forage from improved leys and contains extra nutrients (minerals and phytochemicals) which contribute to livestock health. I demonstrate that biomass from species-rich grasslands can compete with other bioenergy crops, especially Miscanthus (the primary bioenergy feedstock in the region) and that species richness and species composition contributes strongly to the biogas yield of grasslands. Through soil metagenomic analysis I found that while bacterial diversity does not decline with agricultural intensification, fungal diversity decreases and plant, human and livestock microbial pathogens shown to be pathogenic in other ecosystems dramatically increase on agriculturally improved fields compared to species-rich grasslands. Finally, by combining palaeoecological and modern vegetation data I demonstrate that grassland biodiversity was temporally and spatially linked to long-term human management and would revert to oscillating between open grassland and woodland if this management ceases. Grassland biodiversity is thus a finite natural resource with a strong economic and environmental value that can contribute to the development of more sustainable agricultural and bioenergy production systems in the UK.
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