Estimation of CO_2 Assimilation and Emission Flux of Vegetation in Subtropical Island - Taiwan

Jhih-Yuan Yu ； Ken-Hui Chang ； Tu-Fu Chen

《Aerosol and Air Quality Research》 16卷12期 (2016/12) Pp. 3302-3311

https://doi.org/10.4209/aaqr.2016.07.0309

摘要

The goal of the present study is to provide a comprehensive model to estimate CO_2 assimilation and emission flux in Taiwan. In addition to metrological data, the model consists of (1) 83 land-use types including 68 vegetations, (2) NDVILAI transfer functions for various vegetations, (3) leaf width database for 68 vegetations, and (4) LEAFC3 module. The model output includes 2D hourly CO_2 assimilation flux for 68 vegetations with 1 km × 1 km resolution in Taiwan. The results of model evaluation with observed data of 26-day (Nov 12- Dec 7, 2009) CO_2 flux field experiment include: (1) predicted hourly CO_2 uptake fluxes on the daytime match rather well with observed data variations but CO_2 release fluxes on the nighttime show significant underestimate; (2) predicted CO_2 uptake and release fluxes show a relatively good correlation with observed data (R^2 = 0.67); (3) predicted CO_2 assimilation fluxes and isoprene emission fluxes are highly correlated with trends of variation due to photosynthesis. Based on the meteorological data in 2009, the annual total amount of CO_2 assimilation about 115.3 million ton in Taiwan with 79.6 million ton for forests and 35.7 million ton for non-forest vegetations. The CO_2 assimilation amount is higher in the third quarter (July- September) and lower in the first quarter (January- March) for 44.3% and 16.4% of the annual total amount respectively. The spatial distribution of annual CO_2 assimilation amounts are higher in lower and medium altitude mountain areas with an average of around 6- 10 thousand ton km^(-2) y^(-1). The implication of the other results is also discussed.

關鍵字

Flux simulation ； Flux observation ； CO_2 assimilation ； Spatial distribution