Restoring tropical diversity: beating the time tax on species loss.
Fragmentation of tropical forest is accelerating at the same time that already cleared land reverts to secondary growth. Fragments inexorably lose deep-forest species to local extinction while embedded in low-diversity stands of early successional pioneer trees. Pasture matrices undergoing passive secondary succession become a 'pioneer desert' from the vantage of remnant immigration, imposing a 'time tax' of loss of deep-forest plants from forest fragments. However, if seeds of deep-forest trees find pastures, or seedlings are planted there, many will prosper. Bypassing early domination of pioneer trees in regenerating matrices, or enriching matrices with animal-dispersed forest trees, may stem the loss of species from forest fragments and accelerate succession far from the edges of old forest. Synthesis and applications. Planting disperser-limited trees that establish in open ground may bypass 30-70 years of species attrition in isolated remnants by attracting animals that encourage normal processes of seed dispersal into and out of the fragments. Development of criteria for selection of persistent, reasonably rapidly growing, animal-dispersed species that are mixed with planted or naturally arriving pioneers will be an important component of enrichment planting.