Ecology of Dry-Forest Wildland Insects
in the Area de Conservación Guanacaste
Daniel H. Janzen
Tropical dry forest (Murphy and Lugo 1986; Bullock et al. 1995) once occupied at least 60 percent of the forested tropics. Today, it is largely eliminated (Janzen 1988a). Where present, it is almost entirely in some complex state of incomplete and iterative secondary succession (e.g., Janzen 1974a, 1986a, b, 1988b, c, 1990, 2002; Holl 1999; Holl and Kappelle 1999; Toh et al. 1999). The elimination of tropical dry forest is largely due to its ease of removal and perturbation by timber mining and humanfacilitated fire and its comparative ease of occupation by humans engaged in agriculture and their domesticated animals and plants, as compared with lowland tropical rain forest and deserts (Janzen 1988a). Contemporary anthropogenic drying and heating trends are accentuating the process in dry forest and also rendering former cloud forest and rain forest habitats more “dry forest-like” (e.g., Cochrane et al. 1999; Goldammer 1999; Nepstad et al. 1999; Pounds et al. 1999; Still et al. 1999). Although the restoration of tropical dry forest is still possible, humanity will not give the globe back to its wildland denizens, and old-growth tropical dry forest will never again cover large areas.
The ecology of wildland tropical dry-forest insects is therefore largely that of populations and individuals persisting in successional forests on the agroscape or in conserved wildlands that are “being restored. ” The latter are ecological islands that will forever be under the influence of human-generated biotic and climatological forces sweeping through the agroscape (e.g., Janzen 1983d, 1986b, 1988a-d), forces that the comparatively small patches of conserved wildlands cannot escape. As the few conserved wildlands in tropical dry forests are gradually restored over the centuries into whatever ecosystems are able to persist on their sites, future generations may be able to view a somewhat more “old-growth” version of what once existed. The larger the conserved area and the less perturbed it was before restoration began, the closer it will be to the