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

• Published in: Proceedings of the National Academy of Sciences - PNAS 2015-03, Vol.112 (9), p.2788-2793
• Main Authors: Xia, Jianyang, Niu, Shuli, Ciais, Philippe, Janssens, Ivan A., Chen, Jiquan, Ammann, Christof, Arain, Altaf, Blanken, Peter D., Cescatti, Alessandro, Bonal, Damien, Buchmann, Nina, Curtis, Peter S., Chen, Shiping, Dong, Jinwei, Flanagan, Lawrence B., Frankenberg, Christian, Georgiadis, Teodoro, Gough, Christopher M., Hui, Dafeng, Kiely, Gerard, Li, Jianwei, Lund, Magnus, Magliulo, Vincenzo, Marcolla, Barbara, Merbold, Lutz, Montagnani, Leonardo, Moors, Eddy J., Olesen, Jørgen E., Piao, Shilong, Raschi, Antonio, Roupsard, Olivier, Suyker, Andrew E., Urbaniak, Marek, Vaccari, Francesco P., Varlagin, Andrej, Vesala, Timo, Wilkinson, Matthew, Weng, Ensheng, Wohlfahrt, Georg, Yan, Liming, Luo, Yiqi
• Format: Article
• Language: English
• Subjects: Biological Sciences; Carbon cycle; carbon uptake; chlorophyll fluorescence; Climate; climate-change; Ecosystem; ecosystem productivity; Flowers & plants; forest phenology; Life Sciences; Models, Biological; Phenology; photosynthesis; Physiology; Plant Physiological Phenomena; Plants; Productivity; South Dakota; stomatal conductance; variability; Vegetation; vegetation phenology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1413090112

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. 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.