UC Santa Cruz

Increased global awareness of the loss of environmental services that derive from deforestation has triggered calls to promote the recovery of tropical forests. I studied two types of community interactions in tropical forest restoration. The first two chapters present the results of applying tools from phylogenetic ecology to tropical forest restoration. I hypothesized that negative biotic interactions, driven mainly by shared deleterious symbionts, would reduce the natural recruitment of closely related species and the performance of planted seedlings beneath a small monoculture tree canopy. I found non-random phylogenetic structure among coexisting natural recruits, and between them and the overstory trees. The natural recruits beneath legume trees were composed mainly of species further related to each other and to the overstory tree than expected by chance (phylogenetically overdispersed), whereas natural recruits beneath non-legume tree species were more closely related to each other than expected (phylogenetically clustered). This pattern was due to the disproportionate recruitment of Piperaceae, an ancestral clade to all other species, under legume canopies; versus abiotic filters beneath non-legumes leading to dominance of the more recently evolved Asteraceae. In planting experiments, I found the lowest performance on seedlings of the same species as the overstory tree. It was not clear whether the decreased performance of conspecifics was driven by shared pathogens with the overstory because there was no significant phylogenetic signal in host sharing among pathogens. These results suggest that phylogenetic ecology provides some useful information about community assembly processes during tropical forest succession that can guide selection of which species to plant. Finally, I assessed a multi-stakeholder governance regime implemented by the Panamanian Government aimed at achieving sustainable development of the Panama Canal Watershed. I found the governance regime creates important spaces for environmental education and communication between the communities and government actors led by top-down power dynamics. However, tangible results are still mostly lacking. The local communities expressed frustration with the lack of projects and quality of life improvements to date, and the Panama Canal Authority struggles to achieve greater collaboration from other government institutions to solve pressing social issues in the watershed.