CAREER: Disentangling CO2 Fluxes in a Tropical Rainforest Using Carbonyl Sulfide

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

The primary objective of this CAREER project is to quantify gross carbon dioxide (CO2) fluxes in a tropical forest and obtain new understanding of processes linking these fluxes to environmental conditions. This project uses carbonyl sulfide (COS), an atmospheric trace gas, as a proxy for carbon dioxide uptake by plants, since both gases are consumed inside leaf cells by the same enzyme. This method will be used to estimate Gross Primary Production (GPP) through photosynthesis in a tropical rain forest. The results will provide a better understanding of the carbon cycle and its role in the Earth system science. Both the Atmospheric Chemistry Program and the Ecosystem Science Program at NSF are supporting this interdisciplinary project. The Faculty Early Career Development (CAREER) Program is a Foundation-wide activity that offers the National Science Foundation's most prestigious awards in support of junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organizations. Three methods being employed for estimating ecosystem GPP in the rainforest are: (1) a field campaign to measure ecosystem fluxes of COS as novel tracer of GPP, (2) a network of distributed flux chambers to obtain new information on spatial and temporal patterns of plant and soil CO2 fluxes, and (3) an education-outreach program that will collect long-term data on CO2 fluxes across the forest canopy. The field study will take place at La Selva Biological Station in Costa Rica, a site that has hosted over 12 years of ongoing rainforest research. The results of this research will help to answer questions such as how CO2 uptake responds to variations in soil moisture, light and temperature. The study will provide new information on the relationship of ecosystem respiration to changes in temperature during the day and night and help to explain how changes in GPP and ecosystem respiration contribute to large interannual fluctuations in both net ecosystem exchange and forest growth. This research is well integrated with several educational activities, such as the development of a sensor lab course to provide advanced undergraduate students with hands-on field experiences. There are also plans for an outreach program for K-12 students at the Stunt Ranch Reserve (a biological field station) in the Santa Monica Mountains and the creation of a Legacy dataset at the field site involving high school students and college level students from both the U.S. and Costa Rica.