Topographic Distributions of Emergent Trees in Tropical Forests of the Osa Peninsula, Costa Rica

Friday, 18 December 2015: 08:45
2006 (Moscone West)
Chris Balzotti1,2, Gregory Paul Asner1,2, Philip Taylor3, Rebecca J Cole4, Brooke B Osborne5, Cory C. Cleveland6, Stephen Porder7 and Alan R Townsend3, (1)Carnegie Institution for Science Washington, Washington, DC, United States, (2)Carnegie Institution for Science, Department of Global Ecology, Stanford, CA, United States, (3)University of Colorado at Boulder, Boulder, CO, United States, (4)University of Hawaii at Manoa, Honolulu, HI, United States, (5)Brown University, Department of Ecology and Evolutionary Biology, Providence, RI, United States, (6)University of Montana, Missoula, MT, United States, (7)Brown University, Providence, RI, United States
Tropical rainforests are reservoirs of terrestrial carbon and biodiversity. Large and often emergent trees store disproportionately large amounts of aboveground carbon and greatly influence the structure and functioning of tropical rainforests. Despite their importance, controls on the abundance and distribution of emergent trees are largely unknown across tropical landscapes. Conventional field approaches are limited in their ability to characterize patterns in emergent trees across vast landscapes with varying environmental conditions and floristic composition. Here we used a high-resolution light detection and ranging (LiDAR) sensor, aboard the Carnegie Airborne Observatory Airborne Taxonomic Mapping System (CAO-AToMS), to examine the abundance and distribution of tall emergent tree canopies (ETC) relative to surrounding tree canopies (STC), across the Osa Peninsula, a geologically and topographically diverse region of Costa Rica. The abundance of ETC was clearly influenced by fine-scale topographic variation, with distribution patterns that held across a variety of geologic substrates. Specifically, the density of ETC was much greater on lower slopes and in valleys, compared to upper slopes and ridges. Furthermore, using the CAO high-fidelity imaging spectrometer, ETC had a different spectral signature than that of the STC. Most notably, ETC had lower foliar N than STC, which was verified with an independent field survey of canopy leaf chemistry. The underlying mechanisms to explain the topographic-dependence of ETCs and linkages to canopy N are unknown, and remain an important area of research.