Friday, August 10, 2007

PS 72-83: Using artificial canopy gaps to restore Puerto Rican parrot (Amazona vittata) habitat in tropical timber plantations

Faith M. Inman1, Thomas R. Wentworth1, Cavell Brownie1, Martha J. Groom2, and Russ Lea3. (1) North Carolina State University, (2) University of Washington, (3) University of North Carolina

Timber plantations have the potential to catalyze forest regeneration on highly degraded land. However, effective management methods to restore wildlife habitat and native tree diversity in areas planted with non-native timber species are needed. Our study investigated the effectiveness of creating artificial canopy gaps within timber plantations to increase germination, growth, and survival of native tree species that may be important food plants for the Puerto Rican parrot (Amazona vittata). Growth of native advance regeneration and planted seedlings increased significantly in gaps; however, there were no differences in percent germination or survival between gap and closed plots. Percent cover of grasses, shrubs, and vines increased in gaps, but the increased growth of competitors did not prevent native tree seedlings from growing significantly more rapidly in gaps. Removing leaf litter at time of sowing had no effect on germination, growth, or survival of direct seeded species. Creation of canopy gaps by girdling timber trees reduced basal area of non-native tree species and both local and landscape level diversity were predicted to increase in canopy gaps. However, plantations will continue to be dominated by non-native and timber tree species as advance regeneration of these species is common in plantation understories. Our results suggest that restoration of wildlife habitat and native tree diversity in plantations will require continued management to remove non-native species and to promote growth of tree species with high wildlife habitat value.