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Title: Effect of canopy gaps on tree seedling ecophysiology in a Jamaican montane rainforest
Author: Ball, T.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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A controlled experiment was established in primary upper montane rain forest (UMRF) in the Blue Mountains of Jamaica to investigate the ecophysiological response of seedlings of seven tree species to canopy gap formation. The group included one invasive species, the Australian tree Pittosporum undulatum, with a mixture of native and endemic shade tolerant and intolerant species. The main aim was to assess whether the known approximate light demand of seedlings of the species for regeneration correlated to the relative ecophysiological performance of the seedlings across a light gradient. Gaps were created artificially by de-branching of canopy trees, ensuring minimal possible damage to the seedling bank. Resulting light levels were equivalent to those associated with damage from a major hurricane. The photosynthetic characteristics, morphology and longevity of shade leaves and seedlings were investigated in naturally growing seedlings on four gap and four understorey control plots. Above- and below-ground competition and the effect of leaf masking and removal were investigated in separate sub-experiments using potted seedlings. In the understorey, mean levels of total diurnal photosynthetic photon flux density (PPFD) on the uppermost leaf were 2.14% of diurnal integrated above canopy levels. No significant variation occurred among the sevens species, whether defined by instantaneous diffuse light (under cloud), or the proportion of cloud-free time for which sunflecks were experienced. The three indices of light level showed strong, though not always 1:1, interrelationships. The findings give strong ecophysiological backing to existing knowledge of the species' regenerational ecology across a range of disturbed and steady state environments in UMRF. They also give information as to relative physiological performance of native species and the problematic invasive tree Pittosporum undulatum.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available