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.