Attempts to restock large areas of exploited forests in Kenya have been hampered by inadequate understanding of the ecological requirements of indigenous tree species. In particular, very little is known about the responses of these species to different levels of light. This study, therefore, examined the significance of shade and light in regeneration of some important tree species. The species studied were <I>Cordia africana</I> Lam., <I>Vitex keniensis</I> Turill, <I>Markhamia lutea</I> (Benth.) K. Schum. and <I>Olea capensis</I> L. Artificial shading experiments were carried out in the nursery using seedlings of <I>C.africana</I> and <I>V.keniensis</I>. The effects of different shade levels were compared to full sunlight under low and high nutrient regimes. The response of seedlings transferred among different light environments was also examined. The effects of different levels of light quality (R:FR ratios) were tested. In a forest clearing, seedlings of the four species were grown under artificial shading and their responses were compared to those grown under full sunlight. The influence of deep canopy shade on survival and growth in seedlings of the four species was also determined. In the nursery, seedlings of <I>C.africana</I> and <I>V.keniensis</I> maintained positive relative growth rates at irradiance level of 19% of full sun and their growth was enhanced by increasing irradiance. The supply of nutrients at high level also enhanced the growth. Seedlings transferred between light environments acclimated within a month. Acclimation to increase in light availability was faster than acclimation to decrease. Although acclimation was mainly physiological, biomass was allocated in favour of shoots and roots when seedlings were shaded and exposed respectively. The supply of nutrients at higher level had no effects on the acclimation process.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:653542 |
| Date | January 1994 |
| Creators | Konuche, P. K. A. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11008 |
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