The overall aim of this thesis was to develop a better understanding of the role of prescribed burning in moorland management within the Peak District National Park. These moorlands are dominated by heather (Calluna vulgaris (L.) Hull). Prescribed burning is a management tool that used routinely to manage moorland vegetation for grouse and sheep production. The aim is to remove the above-ground foliage and allow the Calluna to resprout from the burned stems. Normally such prescribed burning is done on a rotational matrix, and the aim is to provide a continual supply of moorland vegetation in different stages. This thesis attempted to answer the following questions: (a)How degraded are the moorlands in the Peak District, and does prescribed burning affect species density and restoration potential? (b) What are the environmental factors that influence the response of the plant communities, and how do the constituent species respond after prescribed fire?) (c) Does prescribed burning affect soil chemical properties? (d) What factors affect biomass reduction in prescribed fires on upland moorland? (e) What changes in above-ground biomass, carbon and nitrogen occur during this burning The context for this work is that British moors are high-priority habitats for conservation and it is increasingly recognized that they provide important ecosystem services (carbon accounting, water provision). A combination of field survey and experiments was used. A chronosequence study carried out on five replicate moors showed the vegetation was severely depauperate relative to the species that might be expected in pristine moorland vegetation. Moreover, the seed bank was also depauperate and propagules must be added to restore them. There was an increase in species richness immediately following prescribed burning with a subsequent decline with time. Multivariate analysis produced two gradients, a continuum from relatively lichen-rich vegetation to a graminoid-dominated one, and (b) a post-fire growth response of the Calluna. Calluna was the only species to show increasing growth after burning; all other species were reduced in the oldest vegetation. A similar study of soil properties showed that prescribed burning had a limited effect; some chemical properties changed with the burn-recovery cycle. In order to develop an improved method of prescribed burning the relationship between fire severity and both fire characteristics and environmental variables was assessed experimentally. The results were inconclusive but suggest that the burns with the highest temperatures were flash fires whereas the burns with the lower residence times were smouldering fires that probably converted more biomass to charcoal). A study of prescribed burns showed that the loss of biomass during prescribed burning was very variable and this almost certainly reflected a range of environmental and management factors. The burning method used in the Peak District is designed to minimize biomass loss and it was demonstrated that in some burns this was very successful. The accumulation of above-ground biomass was measured after burning and the oldest stands had much greater biomass values than literature ones and no sign of an asymptote at 50 years.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:539520 |
| Date | January 2011 |
| Creators | Harris, Michael Patrick Kevin |
| Publisher | University of Liverpool |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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