CRB: Testing Enrichment Planting in Fragmented Tropical Landscapes

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The proposed project will experimentally test the efficacy of seed dispersal by bats and birds as compared with seed dispersal by wind in overcoming dispersal limitation of tropical trees in an intensively altered agricultural mosaic of crops, pastures, and forest remnants in Veracruz, Mexico. Recently-developed criteria for selecting late-successional species that survive well in pasture environments will be used to plant 8 half hectare (ha) grids of late-successional wind-dispersed (9 species) and pioneer (3 species) trees and 8 similar grids of late-successional (9 species) and pioneer (3 species) animal-dispersed trees at distances from the Los Tuxtlas forest (Biological Reserve of 644 ha and contiguous forest of 3400 ha) from 100 to 1000 m into the agricultural mosaic. The initial phase will test predictions of seed rain and seedling establishment of pioneer and late-successional species from the reserve as a function of distance from the continuous forest or smaller remnants, age of maturing vegetation, and dispersal syndrome (animal- or wind-dispersed) of planted trees as they mature. The objective is not to restore a tropical forest ecosystem; the land surrounding planted mixed stands and existing remnants will remain intensively managed agricultural landscapes for the foreseeable future. The ultimate objective is to test means of increasing and maintaining connectance among planted stands and remnants using airborne agents of seed dispersal, and in so doing find means of increasing and maintaining faunal and floral diversity within a permanent agricultural mosaic. This is an ambitious scientific proposal with wider implications that may dwarf direct scientific objectives through the training, encouragement of a large and energized undergraduate and graduate student body. The goal will be to encourage and train students to devise ways of managing agricultural mosaics throughout the Neotropics, applying and refining methods that preserve and promote biodiversity using experimental restoration within the reality of tropical agrarian economies.