Joint control of terrestrial gross primary productivity by plant phenology and physiology

Abstract

Terrestrial gross primary productivity (GPP) varies greatly over time and space. A better understanding of this variability is necessary for more accurate predictions of the future climate-carbon cycle feedback. Recent studies have suggested that variability in GPP is driven by a broad range of biotic and abiotic factors operating mainly through changes in vegetation phenology and physiological processes. However, it is still unclear how plant phenology and physiology can be integrated to explain the spatiotemporal variability of terrestrial GPP. Based on analyses of eddy-covariance and satellite-derived data, we decomposed annual terrestrial GPP into the length of the CO 2 uptake period (CUP) and the seasonal maximal capacity of CO 2 uptake (GPP max ). The product of CUP and GPP max explained >90% of the temporal GPP variability in most areas of North America during 2000-2010 and the spatial GPP variation among globally distributed eddy flux tower sites. It also explained GPP response to the European heatwave in 2003 (r 2 = 0.90) and GPP recovery after a fire disturbance in South Dakota (r 2 = 0.88). Additional analysis of the eddy-covariance flux data shows that the interbiome variation in annual GPP is better explained by that in GPP max than CUP. These findings indicate that terrestrial GPP is jointly controlled by ecosystem-level plant phenology and photosynthetic capacity, and greater understanding of GPP max and CUP responses to environmental and biological variations will, thus, improve predictions of GPP over time and space. ecosystem carbon uptake | growing season length | photosynthetic capacity | spatiotemporal variability | climate extreme L arge variability exists among estimates of terrestrial carbon sequestration, resulting in substantial uncertainty in modeled dynamics of atmospheric CO 2 concentration and predicted future climate change (1). The variability in carbon sequestration is partially caused by variation in terrestrial gross primary productivity (GPP) (2), which is the cumulative rate over time of gross plant Significance Terrestrial gross primary productivity (GPP), the total photosynthetic CO 2 fixation at ecosystem level, fuels all life on land. However, its spatiotemporal variability is poorly understood, because GPP is determined by many processes related to plant phenology and physiological activities. In this study, we find that plant phenological and physiological properties can be integrated in a robust index-the product of the length of CO 2 uptake period and the seasonal maximal photosynthesis-to explain the GPP variability over space and time in response to climate extremes and during recovery after disturbance.

Temporal Changes in Coupled Vegetation Phenology and Productivity are Biome-Specific in the Northern Hemisphere

“…This indicates that areas with diverging trends are corresponding to regions with low or negative correlations between LOS and GSI in the NH. This pattern may be due to distinct responses of vegetation phenology and productivity to the ongoing warming in high northern latitudes [54,[68][69][70]. In agreement with the result from this study, Park et al [70] found that vegetation productivity has continuously increased during 2000-2014 compared to decreasing LOS in the boreal and arctic regions of NH.…”

Stand age and species richness dampen interannual variation of ecosystem-level photosynthetic capacity

“…So understanding the factors confluxes is essential to improve the predictability annual GPP 8 , but also correlates with net ecosystem CO 2 exchange 5 .…”

Photosynthetic productivity and its efficiencies in ISIMIP2a biome models: benchmarking for impact assessment studies

“…As attempted by Xia et al (2015), factors related to leaf area (phenology and vegetation structure) and photosynthetic capacity (physiology) could be combined using an appropriate metric. The simulated GPP trend occurred heterogeneously over the land area.…”