Phenology-assisted classification of C3 and C4 grasses in the US Great Plains and their climate dependency with MODIS time series

REMOTE SENSING OF ENVIRONMENT

卷:138

Article

Wang, Cuizhen^1,2  Hunt, E. Raymond, Jr.³  Zhang, Li²  Guo, Huadong² 

[1] Univ Missouri, Dept Geog, Columbia, MO 65211 USA

[2] Chinese Acad Sci, CEODE, Beijing 100094, Peoples R China

[3] ARS, USDA, Hydrol & Remote Sensing Lab, Beltsville, MD 20705 USA

关键词: Great Plains;    MODIS time series;    Plant functional types;    Phenology;    Climate change;   

DOI  :  10.1016/j.rse.2013.07.025

来源: Elsevier

【 摘 要 】

Grassland ecosystems in the North America are primarily composed of C-3 and C-4 plant functional types (PFTs) that have different responses to the changing climate. Knowledge of their spatial distributions and temporal variations helps us better understand the ecological functions and climate dependencies of grasslands. This study used the 500-m MODIS surface reflectance products (MOD09A1) from 2000 to 2009 to extract NDVI time series of C-3 and C-4 grass PFTs in different floristic regions (tallgrass, shortgrass, and mixed-grass prairies.) A set of phenology metrics, including Start of Season, End of Season, Season Length, Peak NDVI, Peak Date, and END VI, were found useful in delineating these grass types. A phenology-assisted decision tree classifier was developed to map the four grass PFTs in the Great Plains. The relative abundance of C-3 and C-4 PFTs generally showed the expected latitudinal shifts. Longitudinal shifts of tallgrass and shortgrass PFTs were also in agreement with the distributions of floristic prairie regions. In shortgrass and northern mixed prairies, shortgrass C-3 was located in the north while shortgrass C-4 was in the south. The native tallgrass C-4 remained in prairie remnants, although other native grasslands had been mostly converted to croplands or tallgrass C-3-dominated pastures. The interannual spatial variations of PFTs were statistically correlated with climate factors over a 10-year study period. The preliminary findings revealed that the strength and direction of correlations varied geographically and seasonally for different PFTs. This spatio-temporally explicit information may provide quantitative inputs in ecological forecasting for various climate change scenarios. (C) 2013 Elsevier Inc All rights reserved.

【 授权许可】

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