Date of Award
Doctor of Philosophy
Richard B. Hall
Six aspects of the ecology and management of mahogany (Swietenia macrophylla King) regeneration in Quintana Roo, Mexico, were studied: (1) the effect of partial overstory removal on natural regeneration; (2) the development of a thinning simulation program, "ThinSim"; (3) a comparison of four methods to kill trees for partial overstory removal; (4) the survival of mahogany seedlings one year after a partial overstory removal; (5) the growth of some tropical trees species three years after a partial overstory removal; and (6) the sprouting capability of seventeen tropical tree species;Natural regeneration of commercially valuable species in tropical forests represents a major challenge to tropical foresters because the valuable species represent a very small proportion of the trees in a stand. A study was initiated in which five 0.5 ha plots were subjected to different levels of overstory removal. The regeneration that came in after the removal and the growth of the residual trees was studied for three years. Overstory removal encouraged natural regeneration of light demanding species, such as mahogany and other commercially valuable species. Although overstory removal also had a positive effect on the regeneration of currently, less valuable species, an increase in the number of seedlings of mahogany and other valuable species is important because it increases the potential value of the forests, which will help ensure their existence. A program that simulates overstory removal was developed to help evaluate different overstory removal strategies. It was successfully used to design a mahogany regeneration study. Overstory removal requires that some trees be eliminated. From studies that were established, girdling is recommended because it was almost as successful at killing trees as herbicides, and it is safer to do than applying herbicides. For faster results, however, Esteron 47 was the most effective in killing dicotyledonous trees, and Banvel°lerCST was the most effective in killing palms. Different levels of overstory removal were performed on 25 0.2 ha plots that were then seeded with mahogany seeds. The levels of overstory removal were very low, thus it was difficult to evaluate their effect on mahogany germination and seedlings survival. Five 0.5 ha plots grew an average of 2 m[superscript]2 of basal area three years after of an overstory removal. Individual tree diameter growth was weakly correlated with the level of overstory removal. The number of sprouts produced by 128 stumps (seventeen tree species) were counted. Although the species are not useful for timber production, they can be used for fire wood, construction materials, edible fruits, and forage. Information on their sprouting ability can be very useful in managing the species by coppice methods for products other than timber.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Negreros-Castillo, Patricia, "Ecology and management of mahogany (Swietenia macrophylla King) regeneration in Quintana Roo, Mexico " (1991). Retrospective Theses and Dissertations. 9561.