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Title: Soil seed banks and ecological restoration : above and below ground effects of environment, management and intraspecific variation
Author: Mercado, Sofía Isabel Basto
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2011
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Abstract:
The aim of this thesis is to contribute to the understanding of how the response of communities (above and below ground) to environment degradation are reflected in seed banks and, how this knowledge can be used to suggest improved application of ecological restoration processes. Two study areas were selected, one at Buxton Climate Change Impacts Laboratory, a site near Buxton, and the other at Wardlow Hay-Cop, in Cressbrook Dale National Nature Reserve, both located in the Derbyshire, UK. This study is organized in the following four sections. I. Chapter 11 examines the impact of the long-term management and changes in precipitation on calcareous grassland seed banks. More than two decades of dereliction have had the largest effects followed by the effects of more than ten years of summer drought. Both changed species composition and, declined seed abundance. In addition, species richness decreased in dereliction. 3. Chapter III investigates the effects of the long-term nitrogen deposition on acid grassland seed banks. More than one decade of N deposition caused shifts in species composition. decrease richness, seed density and. the abundance of functional groups. Moreover, seed bank populations were unable to recover after more than 4 years of ceasing N deposition. 4. Chapter IV explores the effects of soil pH on seed persistence. Seed density, grasses seed abundance the probability that Hypericum pulchrum seeds persist declined as soil pH increased. 5. Chapter V investigates the extent to which the intraspecific trait variation in the same community differs between the components of mature plant population and seed bank, arising from a possible trade-off between investment in seed banks and vegetative growth. Seed bank were not representative of mature plant population. Overall, larger individuals invested more in sexual reproduction than the smaller and, per unit of total biornass, seed- originating individuals invested more in vegetative than in reproductive traits. Therefore, there is no evidence of the potential trade-off between investment in seed banks (via seed production) and vegetative growth in the calcareous grassland species at Buxton. We concluded that the potential of seed banks to assist the restoration is lower in calcareous than acid grass lands. Moreover, the relevance of seed banks is lower in those affected by dereliction and summer drought and, in acid grass lands affected by N deposition the potential is very limited. In addition, the genetic diversity of calcareous grassland species cannot be recovered by using seed banks. Therefore, the recovery of seed banks and above-ground vegetation should be integrated together into restoration programmes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.574481  DOI: Not available
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