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Title: Factors inhibiting succession in degraded grasslands in the Knuckles Forest Reserve, Sri Lanka
Author: Gunaratne, A. M. Thilanka A.
ISNI:       0000 0001 3522 1960
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2007
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Seedlings of wood plants are rare in degraded grasslands in Knuckles Forest Reserve in central Sri Lanka up to 30 years after the abandonment of tea cultivation.  I tested the importance of five biotic factors (seed dispersal, soil seed bank density, seedling emergence, mycorrhizal associations, herbivory), four abiotic factors (fire, microclimatic conditions, soil nutrient availability, and water availability) and their interactions (competition, disturbance) as determinants of succession in these manmade grasslands.  I also investigated the feasibility of using four native species (Syzygium spathulatum Thw., Macaranga indica Wight, Symplocos cochinchinensis (Lour.) S. Moore, and Dimocarps longan Lour.) for restoring these lands. The limited rate of seed dispersal of woody plants was the most important barrier for tree establishment at the study site.   Only 0.3% of the grassland seed rain comprised woody plant seeds, and only one seed each from two late successional tree species were recorded as dispersing into the grassland during an 18 month period.  Seedling emergence by woody plants was lower in the grassland (mean 0.02 m-2yr-1) than in adjacent forest (mean 6.03 m-2y-1).  Photosynthetically active radiation, air temperature and soil temperature at ground level were significantly higher for the grassland than the forest.  Herbivory had a more pronounced negative effect on the emergence of woody plants in the grassland than did fire. I propose a suitable design for a model restoration programme based on the creation of vegetation islands of early successional species to act as attractive ‘stepping stones’ for seed dispersers moving between remnant forest patches to forage.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available