Annual growth rings in dry tropical forest trees

Tropical dry forests are one of the most diverse ecosystems on earth. Despite their ecological, commercial and cultural importance, however, we still know little about their population dynamics. In this thesis I focus on dendrochronological problems and possibilities in the dry tropical biome. I begin with an exhaustive compilation of all the tropical tree species that have been shown to produce annual growth rings, for this I include both wet and dry tropical forests. I follow with a study that was conducted in a tropical dry forest in western Mexico to determine the periodicity of radial wood formation in six drought-deciduous tree species. It is suggested that the intense drought that is prevalent in this climate type induces the cessation of cambial activity in these trees; and thus annual ring formation may be assumed for non-riverine drought-deciduous tree species. A third chapter details an experimental study of the effect of rare dry season rains on leafless tree species. In particular, I examined the relationship between one-time water receipt and (1) the degree of bud burst (and, for one species, flowering), and (2) the formation of a false ring. Also, I used long-term records at a nearby meteorological station to determine the frequency of a rain event exceeding a particular intensity. Finally, I end with a broad review of dry tropical forest ecology, the biome known to be most conducive to the formation of annual growth rings in tropical trees.