Volume 16, No. 12, December 2016, Pages 3302-3311 PDF(396 KB)
Estimation of CO2 Assimilation and Emission Flux of Vegetation in Subtropical Island - Taiwan
Jhih-Yuan Yu1, Ken-Hui Chang2, Tu-Fu Chen2
1 Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Douliu, Yunlin 64002, Taiwan
2 Department of Safety, Health and Environmental Engineering, National Yunlin University of Science and Technology, Douliu, Yunlin 64002, Taiwan
- A model was established to estimate CO2 flux with 1 × 1 km2 resolution in Taiwan.
- The model was evaluated in two ways with CO2 observed uptake and release flux data.
- Annual CO2 assimilation flux is higher in lower and medium altitude mountain areas.
- Annual CO2 assimilation amount was 115.3 million ton with 69% for forests in Taiwan.
The goal of the present study is to provide a comprehensive model to estimate CO2 assimilation and emission flux in Taiwan. In addition to metrological data, the model consists of (1) 83 land-use types including 68 vegetations, (2) NDVI-LAI transfer functions for various vegetations, (3) leaf width database for 68 vegetations, and (4) LEAFC3 module. The model output includes 2D hourly CO2 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) CO2 flux field experiment include: (1) predicted hourly CO2 uptake fluxes on the daytime match rather well with observed data variations but CO2 release fluxes on the nighttime show significant underestimate; (2) predicted CO2 uptake and release fluxes show a relatively good correlation with observed data (R2 = 0.67); (3) predicted CO2 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 CO2 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 CO2 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 CO2 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.
Flux simulation; Flux observation; CO2 assimilation; Spatial distribution.