Management of Habitat Fragments in a Tropical Dry Forest: Growth

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Abstract
Tropical conservation biology is inescapably the biology of habitat fragments and has been focused on habitat decay. Habitat restoration is primarily the initiation, growth, and coalescence of habitat fragments. Management of a tropical wildland will become the art and science of arresting the decomposition of habitat fragments and promoting their growth and coalescence. Forces that determine accumulation of structure and species are significantly within human control. Today''s management actions will determine the nature of wildland habitats for centuries to come. Tropical dry forest is the most threatened of all the major lowland tropical forest habitats, simply because it has always occupied some of the lands most easily farmed in the tropics, and because it is so susceptible to fire. When dry forest and fields are abandoned and therefore allowed to return to dry forest, there are two principal kinds of forest initiation (assuming that there are nearby seed sources). a. When large pastures are downwind of a relatively intact forest, the initial invasion is primarily by individuals of large wind-dispersed trees that will persist and characterize the site for hundreds of years. However, these tree species are a minority of the total flora. Such forests of wind-dispersed trees are relatively inhospitable to animals, highly deciduous, and relatively species-poor. b. When there is any kind of attraction for animals in an abandoned open area, they may perch in it or rest below it while crossing the open area. This results in accumulation of an entirely vertebrate-dispersed forest patch. Such patches may grow and coalesce to form a forest type as artificial as is a wind-generated forest. Vertebrate-generated forests contain more food items of interest to animals, are more species rich, and are more evergreen than are wind-generated forests. As large areas of abandoned low-grade farm and ranch land are returned to dry forest, the manager of national parks or other wildlands is confronted with the difficult decision of just which of the above, or other, forest types is to be promoted. The same will apply to rainforest when its restoration becomes a focus of concern.