New Approaches to Tropical Reforestation: Large- and Local-Scale Benefits from an Ecological Look at an Applied ProblemEPA Grant Number: F07F21049
Title: New Approaches to Tropical Reforestation: Large- and Local-Scale Benefits from an Ecological Look at an Applied Problem
Investigators: Massad, Tara Joy
Institution: Tulane University of Louisiana
EPA Project Officer: Michaud, Jayne
Project Period: January 1, 2007 through January 1, 2010
RFA: STAR Graduate Fellowships (2007) RFA Text | Recipients Lists
Research Category: Ecological Assessment , Academic Fellowships , Fellowship - Terrestrial Systems Ecology
In order to address the loss of tropical rainforests and the accompanying species extinctions and carbon dioxide emissions, this research program will explore ecologically based methods for reforestation. The majority of Neotropical reforestation has focused on tree species with economically attractive timber potential and relies on synthetic pesticides to control insect herbivores that negatively affect seedling survival. This work will contribute to a more sustainable form of reforestation, defining it as the recreation of natural forest habitat. To do so, tree species that produce their own chemical defenses against insect herbivores will be planted and are expected to survive without pesticide application. By also using a high diversity of species in various planting regimes, these experiments will lead to reforestation designs that quickly and effectively sequester carbon dioxide and promote a return to natural conditions.
This research applies tools from the field of chemical ecology to the issue of tropical reforestation in the lowlands of Costa Rica and the Atlantic Rainforest of Brazil. In Costa Rica, tree species were selected that are capable of manufacturing their own chemical defenses (particularly a group of chemicals called saponins). These seedlings were planted in monocultures and mixed plots with a fast-growing, but undefended, species to test the hypothesis that well defended species survive better and more effectively allow for habitat restoration than do traditionally used timber species. The work also tests the ecological principle of associational resistance through the use of differing levels of diversity. Over two years time, the growth, herbivore damage, and saponin chemistry of these seedlings will be monitored.
The project in Brazil is on a large scale and compares reforestation plots of differing densities and diversities to discover designs that best allow for rapid regeneration of natural conditions. Within these plots, growth, herbivore damage, and plant defense traits are being evaluated over four years. The regeneration potential of species in these different plot treatments and the effects of their defenses on growth and survival will be analyzed for use in future projects.
These experiments are based on the hypothesis that an emphasis on naturally well defended species in reforestation will reduce losses due to herbivory and allow for planting without the addition of toxic pesticides. This will make reforestation more accessible on both small and large scales. Saponins and leaf toughness are hypothesized to be particularly effective defenses against leaf cutter ants (Atta spp), which are the primary pests in tropical reforestation. Plots using higher diversities should also be more successful as the complexity of the habitat may limit insects looking for food plants. Overall, a successful return to natural conditions is predicted from planting with chemically defended species at high diversities. These experiments will emphasize the roles of chemical and traditional ecology in conservation planning and will help in future reforestation efforts.