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Title: Environmental influences on seedling growth
Author: Agyeman, Victor Kwame
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1994
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The tropical high forests of West Africa have been under stress due to a greater dependence on wood resources. Logging rate has more than doubled within the last decade. However, the exact effects of logging on vegetation composition and the degree of canopy opening that should be created in the forest to ensure the regeneration of timber tree species are not known. Three major experiments were carried out to determine the ecophysiological responses of timber tree species in different irradiances and red:far-red ratios. (1) 16 tree species were grown in six neutral shade treatments (2, 6, 27, 42 and 65% full sun) and their growth assessed by standard measurements used in growth analysis (biomass, height, stem diameter, leaf area, leaf production and mortality). (2) Eight species, of which six were also used in the shade house experiment, were grown in a series of artificially-created gaps in two forest sites differing in annual rainfall. Gaps created received 1-2, 5, 10, 15, 30 and 66% full sun. (3) Possible differences in the results between shade house and forest experiments due to differences in light quality (red:far-red ratio) were tested separately. Differences in red:far-red ratio has little effect of growth but showed some influence on allocation of biomass. Seedling growth response of species were higher in shade houses compared to the two field sites and higher in the wet compared to dry forests. Sixteen tropical timber tree species were ranked on an ecological (shade tolerance) gradient based on their differential growth response to light. The results indicate that the ranking of species on an ecological gradient is robust and potentially more reliable than intuitive classification of species into groups.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available