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Title: Air pollution and climate change effects on grassland ecosystems
Author: Lee, Mark
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2012
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Grassland ecosystems extend across a substantial area of the world’s surface, providing many valuable ecosystem services including carbon sequestration, biodiversity preservation and food provision. Global and local environmental changes are anticipated in the future, including shifts in climatic conditions and changes to the composition of the atmosphere. This thesis adds to our understanding of how grassland communities respond to air pollution and climate change using two key methodologies. Firstly, a suite of environmental variables were measured in calcareous grassland ecosystems along transects adjacent to roads. This allowed quantification of plant compositional changes and identification of the likely drivers of plant compositional changes nearer roadsides. Evidence of road-derived changes to air quality, soil biogeochemistry and hydrology at roadsides are presented. The key messages being that road proximity was associated with increased abundances of nitrophilic species and also of species not typical of calcareous habitats. Secondly, a mesotrophic grassland ecosystem was exposed to a factorial combination of end-of-century rainfall regimes (+ 15 % winter rainfall and – 30 % summer rainfall) based on IPCC 4th Assessment projections and nitrogen enrichment. Plant productivity and species composition were resistant to nitrogen enrichment throughout the three year study. Above-ground plant biomass declined in rainfall manipulated plots by the third year, with evidence of increasing forb abundance and declining grass abundance. These data can assist projections of grassland responses to environmental change in the future and inform management decisions aimed at preventing decline in natural grasslands and declines in the ecosystem services that grasslands currently provide.
Supervisor: Davies, Linda ; Power, Sally Sponsor: Big Lottery Fund
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral