In coastal peatlands, factors related to global climate change are expected to alter the flux of CO2 from soils to the atmosphere. Plant-soil feedbacks are expected to yield increased ecosystem stability, and strong feedback is often expressed in coastal systems, especially in peatlands. However, peatland characteristics that influence these feedbacks are not well studied, and could elucidate a better understanding of C dynamics. New comparative studies are sought to advance understanding of these dynamics at the Florida Coastal Everglades, the only mainland US LTER site located at a subtropical latitude. In this study, we established a leaf litter decomposition experiment to examine leaf litter dynamics with variation in litter quality across a soil P gradient in Bocas del Toro, Panama. We utilized a standard litter bag technique to quantify changes in mass loss, nutrient and isotope dynamics of low quality (sedge) and high quality (palm) leaf litter over 64 weeks. Upon initial deployment, nutrient and carbon concentrations of low quality sedge litter were 0.005 ± 0.0004% P, 0.41± 0.07% N, 46.2 ± 0.22% C, -3.72 ± 0.59 ‰ 15N and -30.83 ± 0.07‰ 13C. Nutrient and isotopic values for high quality palm litter were 0.05 ± 0.045% P, 1.03 ± 0.03% N, 48.2 ± 0.23% C, 1.26 ± 0.26‰ 15N and
-31.27 ± 0.08‰ 13C. Our preliminary results show that low quality leaf litter P increases over time in all sites except the site with lowest soil P (Sphagnum bog). After 8 months of decomposition, P content of low quality litter equals or is significantly less than P content of high quality litter, but significantly exceeds the P content of high quality litter after 16 months at these same sites. The P content of the high quality litter decreases significantly between the initial and 16 month sampling intervals in sites with lower canopy DBH (diameter at breast height). High quality palm litter had 50% or more mass remaining after 16 months regardless of site quality whereas low quality sedge litter had significantly more mass remaining (~50%) in the low soil P environment of the Sphagnum bog when compared to other sites. These results provide preliminary evidence for strong plant-soil feedback along a soil P gradient in this tropical coastal peatland of Panama that varies depending on litter quality. Palm litter exerts a stronger influence on the physical breakdown of its leaf materials whereas environmental controls exert a stronger influence on leaf litter of lower quality, especially where soil P concentrations exceed that of the environment from which it originates. Our overall goal will thus be to compare these and further results of this experiment with those of similar anticipated experiments to be conducted at the FCE LTER.