Imperial College London

Professor Iain Colin Prentice

Faculty of Natural SciencesDepartment of Life Sciences (Silwood Park)

Chair in Biosphere and Climate Impacts



+44 (0)20 7594 2354c.prentice




1.1Centre for Population BiologySilwood Park






BibTex format

author = {Collalti, A and Prentice, I},
doi = {treephys/tpz034},
journal = {Tree Physiology},
pages = {1473--1483},
title = {Is NPP proportional to GPP? Waring’s hypothesis twenty years on},
url = {},
volume = {39},
year = {2019}

RIS format (EndNote, RefMan)

AB - Gross primary production (GPP) is partitioned to autotrophic respiration (Ra) and net primary production (NPP), the latter being used to build plant tissues and synthesize non-structural and secondary compounds. Waring et al. (1998) suggested that a NPP:GPP ratio of 0.47 ± 0.04 (s.d.) is universal across biomes, tree species and stand ages. Representing NPP in models as a fixed fraction of GPP, they argued, would be both simpler and more accurate than trying to simulate Ra mechanistically. This paper reviews progress in understanding the NPP:GPP ratio in forests during the 20 years since Waring et al.. Research has confirmed the existence of pervasive acclimation mechanisms that tend to stabilize the NPP:GPP ratio, and indicates that Ra should not be modelled independently of GPP. Nonetheless, studies indicate that the value of this ratio is influenced by environmental factors, stand age and management. The average NPP:GPP ratio in over 200 studies, representing different biomes, species and forest stand ages, was found to be 0.46, consistent with the central value that Waring et al. proposed but with a much larger standard deviation (± 0.12) and a total range (0.22 to 0.79) that is too large to be disregarded.
AU - Collalti,A
AU - Prentice,I
DO - treephys/tpz034
EP - 1483
PY - 2019///
SN - 1758-4469
SP - 1473
TI - Is NPP proportional to GPP? Waring’s hypothesis twenty years on
T2 - Tree Physiology
UR -
UR -
VL - 39
ER -