Estimating Carbon Flux Phenology with Satellite-Derived Land Surface Phenology and Climate Drivers for Different Biomes: A Synthesis of AmeriFlux Observations

Wenquan Zhu,Guangsheng Chen,Minjie Mou,Jianhong Liu,Nan Jiang,Bruno Hérault

doi:10.1371/journal.pone.0084990

Wenquan Zhu, Guangsheng Chen + Show 4 more

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https://doi.org/10.1371/journal.pone.0084990

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Journal: PloS one	Publication Date: Dec 27, 2013
Citations: 12	License type: CC BY 4.0

Affiliation: Beijing Normal University, Oak Ridge National Laboratory

Abstract

Carbon Flux Phenology (CFP) can affect the interannual variation in Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands), using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU) by more than 70% and End of Carbon Uptake (ECU) by more than 60%. The Root Mean Square Error (RMSE) of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

Highlights

Vegetation phenology plays an important role in adjusting the annual Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere [1,2,3,4,5]
This study provided a methodology to estimate Carbon Flux Phenology (CFP) metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for different biomes through a synthesis of AmeriFlux observations
LSP metrics combined with optimal climate drivers can explain Start of Carbon Uptake (SCU) variability by more than 70% and End of Carbon Uptake (ECU) variability by more than 60%

Summary

Introduction

Vegetation phenology plays an important role in adjusting the annual Net Ecosystem Exchange (NEE) (see Acronym S1 in supporting information for a list of acronyms and definitions used in this paper) of carbon between terrestrial ecosystems and the atmosphere [1,2,3,4,5]. The interannual variation in ecosystem productivity caused by vegetation phenology shifts was widely investigated by field studies [6,7,8,9] and ecosystem models [10,11,12,13,14]. Some previous studies have shown a positive effect of Growing Season Length (GSL) on net productivity (e.g., 5.9 g CNm22Nd21 in a deciduous forest [15] and around 4 g CNm22Nd21 in a subtropical forest stand [16]). The length of Carbon Uptake Period (CUP) has much predictive power about the spatial variation of annual NEE. The length of CUP can explain 80% of the spatial variance in annual NEE for deciduous forests across a latitudinal and continental gradient [17]

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