Title: Environmental controls on the light use efficiency of terrestrial gross primary production

Abstract

Abstract Gross primary production (GPP) by terrestrial ecosystems is a key quantity in the global carbon cycle. The instantaneous controls of leaf‐level photosynthesis are well established, but there is still no consensus on the mechanisms by which canopy‐level GPP depends on spatial and temporal variation in the environment. The standard model of photosynthesis provides a robust mechanistic representation for C ₃ species; however, additional assumptions are required to “scale up” from leaf to canopy. As a consequence, competing models make inconsistent predictions about how GPP will respond to continuing environmental change. This problem is addressed here by means of an empirical analysis of the light use efficiency (LUE) of GPP inferred from eddy covariance carbon dioxide flux measurements, in situ measurements of photosynthetically active radiation (PAR), and remotely sensed estimates of the fraction of PAR (fAPAR) absorbed by the vegetation canopy. Focusing on LUE allows potential drivers of GPP to be separated from its overriding dependence on light. GPP data from over 100 sites, collated over 20 years and located in a range of biomes and climate zones, were extracted from the FLUXNET2015 database and combined with remotely sensed fAPAR data to estimate daily LUE. Daytime air temperature, vapor pressure deficit,more » diffuse fraction of solar radiation, and soil moisture were shown to be salient predictors of LUE in a generalized linear mixed‐effects model. The same model design was fitted to site‐based LUE estimates generated by 16 terrestrial ecosystem models. The published models showed wide variation in the shape, the strength, and even the sign of the environmental effects on modeled LUE. These findings highlight important model deficiencies and suggest a need to progress beyond simple “goodness of fit” comparisons of inferred and predicted carbon fluxes toward an approach focused on the functional responses of the underlying dependencies.« less

Authors:

Bloomfield, Keith J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6492-4507"

Stocker, Benjamin D.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-2697-9096"

Keenan, Trevor F.  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-3347-0258"

Prentice, I. Colin  ^[4]

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• Search DOE PAGES for ORCID "0000-0002-1296-6764"

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+ Show Author Affiliations

1. Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London Ascot UK
2. Department of Environmental Systems Science, ETH Zurich Switzerland, Swiss Federal Institute for Forest, Snow and Landscape Research WSL Birmensdorf Switzerland, Institute of Geography University of Bern Bern Switzerland, Oeschger Centre for Climate Change Research University of Bern Bern Switzerland
3. Department of Environmental Science, Policy and Management, UC Berkeley Berkeley California USA, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory Berkeley California USA
4. Georgina Mace Centre for the Living Planet, Department of Life Sciences, Imperial College London Ascot UK, Department of Biological Sciences Macquarie University North Ryde New South Wales Australia, Ministry of Education Key Laboratory for Earth System Modelling, Department of Earth System Science Tsinghua University Beijing China

Publication Date:

Fri Nov 25 00:00:00 EST 2022

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); National Aeronautics and Space Administration (NASA)

OSTI Identifier:

1900055

Alternate Identifier(s):

OSTI ID: 1900056; OSTI ID: 1987512

Grant/Contract Number:  

AC02-05CH11231; 80NSSC21K1705

Resource Type:

Published Article

Journal Name:

Global Change Biology

Additional Journal Information:

Journal Name: Global Change Biology Journal Volume: 29 Journal Issue: 4; Journal ID: ISSN 1354-1013

Publisher:

Wiley-Blackwell

Country of Publication:

United Kingdom

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; diffuse radiation; eddy covariance; FLUXNET; light use efficiency; soil moisture; temperature; terrestrial biosphere model; vapor pressure deficit