Tree seedling demography after selective logging in a tropical moist semi-deciduous forest in Ghana
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Date
2007-08-25
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Abstract
Seedling recruitment, growth and mortality are critical determinants of successful forest regeneration. This study assessed regeneration success of a logged forest by comparing the species composition, diversity, density, recruitment, mortality and growth of naturally established seedlings in 160 seedling plot samples of ~60 m2 located at random on main skid trails, secondary skid trails, felled tree gaps and unlogged parts of the forest. The study was done within a 128 ha compartment in a selectively logged tyoist Sen^ deciduous forest in Ghana over a period of 33 months.
There was a shift in dominance in the species composition of the seedling populations in all the sites over the study period. Initially seedling composition was dominated by pioneers but after 33 months seedling population in all sites was dominated by non- pioneers. Seedling densities showed an increase initially in all the sites after logging but declined after 12 months. These high seedling densities were driven by four (Albizia zygia, Ceiba pentandra, Celtis mildbraedii and Turreanthus africanus) out of the 38 species that regenerated. All four species exhibited a period of exceptionally high new seedling recruitment in the first 12 months. These periods were not coincident among the species but instead reflected the species' phenological differences. Overall seedling diversity differ significantly among disturbance types initially but after 33 months diversity was lower in the unlogged areas though not significant. Seedling mortality was highest amongst pioneers and for each functional group in unlogged areas of the forest. Seedling growth rates were higher in the logged areas of the forest.
These results show that disturbed areas appear to be suitable sites for the regeneration of timber species following logging but the long-term fate of trees growing on these areas remains uncertain as growth rates declined with time.
Description
A thesis submitted to the College of Agriculture and Natural resources, Department of Silviculture and Forest Management, 2007