Phenology and gross primary production of sugarcane plantations in Brazil and USA

Authors: XIN, FENGFEI - Fudan University; XIAO, XIANGMING - University Of Oklahoma; CABRAL, OSVALDO - Embrapa; White, Paul; GUO, HAIQIANG - Fudan University; MA, JUN - Fudan University; LI, BO - Fudan University; ZHAO, BIN - Fudan University

Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2020
Publication Date: 7/8/2020
Citation: Xin, F., Xiao, X., Cabral, O., White Jr, P.M., Guo, H., Ma, J., Li, B., Zhao, B. 2020. Phenology and gross primary production of sugarcane plantations in Brazil and USA. Remote Sensing. 12(14):2186. https://doi.org/10.3390/rs12142186
DOI: https://doi.org/10.3390/rs12142186

Interpretive Summary: Sugarcane croplands provide the raw materials to meet both sugar and fiber needs in our human society. As sugarcane grows, it incorporates carbon dioxide into biomass through photosynthesis, and is thus an important carbon sink in agro-ecosystems. This assimilation is referred to as gross primary production (GPP). Accurate information on sugarcane growth stages (tillering, stalk elongation, harvest etc.) is equally important for understanding the carbon cycle. In this study we combined the data from the sugarcane eddy covariance flux tower sites in Brazil and the USA, satellite images, and computer models to improve our understanding and monitoring of sugarcane growth. Satellite images showing seasonal vegetation growth were obtained using the Moderate Resolution Imaging Spectroradiometer (MODIS), a payload imaging sensor aboard the NASA scientific research satellite ‘Terra’ orbiting Earth. The computer model, Vegetation Photosynthesis Model – VPM, used MODIS images and available climate data to provide GPP estimates that were similar to the flux tower-measured GPP. The results suggest that VPM may be a valuable tool for estimating GPP of sugarcane crops around the world.

Technical Abstract: Sugarcane (complex hybrids of Saccharum spp.) croplands provide cane stalk biomass feedstock to meet the needs for sugar and biofuels in our human society. Gross primary production (GPP) of sugarcane croplands is an important carbon flux in sugarcane agro-ecosystems. Accurate information on phenology and GPP of sugarcane croplands is critical for understanding the carbon cycle and monitoring sugarcane cropland growing conditions. In this study we combined the data from the sugarcane eddy covariance flux tower sites, satellite images and data-driven models. The seasonal dynamics of climate, vegetation indices derived from images taken by Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, and GPP estimates (GPPEC) at two sugarcane flux tower sites in Brazil and USA reveal the consistency in sugarcane phenology (crop calendar; green-up dates and harvesting dates) as estimated by the vegetation indices and GPPEC data. Land Surface Water Index (LSWI) is useful to delineate phenology of sugarcane croplands. We found that sugarcane GPPEC data had stronger linear relationship with Enhanced Vegetation Index (EVI) than with Normalized Difference Vegetation Index (NDVI). We also ran the Vegetation Photosynthesis Model (VPM), driven by MODIS images and climate data, to estimate GPP at the two sugarcane sites (GPPVPM). The seasonal dynamics of VPM-based GPP estimates (GPPVPM) agreed reasonably well with the seasonal dynamics of GPPEC at the two sites, which suggests that the VPM is a valuable tool for estimating GPP of sugarcane agro-ecosystems in Brazil and USA. This study clearly highlights the potential of eddy flux technology, satellite technology and data-driven models to better understand and monitor sugarcane croplands, which provide essential feedstock for sugar and biofuel production in the world.