Changes in timing of seasonal peak photosynthetic activity in northern ecosystems

Taejin Park; Chi Chen; Marc Macias-Fauria; Hans Tømmervik; Sungho Choi; Alexander Winkler; Uma S Bhatt; Donald A Walker; Shilong Piao; Victor Brovkin; Ramakrishna R Nemani; Ranga B Myneni

doi:10.1111/gcb.14638

Changes in timing of seasonal peak photosynthetic activity in northern ecosystems

Glob Chang Biol. 2019 Jul;25(7):2382-2395. doi: 10.1111/gcb.14638. Epub 2019 May 8.

Authors

Taejin Park¹, Chi Chen¹, Marc Macias-Fauria², Hans Tømmervik³, Sungho Choi⁴, Alexander Winkler^{5

6}, Uma S Bhatt⁷, Donald A Walker⁸, Shilong Piao⁹, Victor Brovkin⁵, Ramakrishna R Nemani¹⁰, Ranga B Myneni¹

Affiliations

¹ Department of Earth and Environment, Boston University, Boston, Massachusetts.
² School of Geography and the Environment, University of Oxford, Oxford, United Kingdom.
³ Norwegian Institute for Nature Research, FRAM - High North Research Centre for Climate and the Environment, Tromsø, Norway.
⁴ Rhombus Power Inc., NASA Ames Research Park, Moffett Field, California.
⁵ Max-Planck-Institute for Meteorology, Hamburg, Germany.
⁶ International Max-Planck Research School for Earth System Modeling, Hamburg, Germany.
⁷ Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska.
⁸ Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska.
⁹ College of Urban and Environmental Sciences, Peking University, Beijing, China.
¹⁰ NASA Ames Research Center, Moffett Field, California.

PMID: 30943321
DOI: 10.1111/gcb.14638

Abstract

Seasonality in photosynthetic activity is a critical component of seasonal carbon, water, and energy cycles in the Earth system. This characteristic is a consequence of plant's adaptive evolutionary processes to a given set of environmental conditions. Changing climate in northern lands (>30°N) alters the state of climatic constraints on plant growth, and therefore, changes in the seasonality and carbon accumulation are anticipated. However, how photosynthetic seasonality evolved to its current state, and what role climatic constraints and their variability played in this process and ultimately in carbon cycle is still poorly understood due to its complexity. Here, we take the "laws of minimum" as a basis and introduce a new framework where the timing (day of year) of peak photosynthetic activity (DOY_Pmax ) acts as a proxy for plant's adaptive state to climatic constraints on its growth. Our analyses confirm that spatial variations in DOY_Pmax reflect spatial gradients in climatic constraints as well as seasonal maximum and total productivity. We find a widespread warming-induced advance in DOY_Pmax (-1.66 ± 0.30 days/decade, p < 0.001) across northern lands, indicating a spatiotemporal dynamism of climatic constraints to plant growth. We show that the observed changes in DOY_Pmax are associated with an increase in total gross primary productivity through enhanced carbon assimilation early in the growing season, which leads to an earlier phase shift in land-atmosphere carbon fluxes and an increase in their amplitude. Such changes are expected to continue in the future based on our analysis of earth system model projections. Our study provides a simplified, yet realistic framework based on first principles for the complex mechanisms by which various climatic factors constrain plant growth in northern ecosystems.

Keywords: carbon cycle; climate change; climate constraint; earth system model; eddy covariance; gross primary productivity; law of minimum; photosynthetic seasonality; remote sensing.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Carbon Cycle
Ecosystem*
Photosynthesis*
Plants
Seasons