TY - JOUR

T1 - Plant interactions alter the predictions of metabolic scaling theory

AU - Lin, Yue

AU - Berger, Uta

AU - Grimm, Volker

AU - Huth, Franka

AU - Weiner, Jacob

PY - 2013

Y1 - 2013

N2 - Metabolic scaling theory (MST) is an attempt to link physiological processes of individual organisms with macroecology. Itpredicts a power law relationship with an exponent of 24/3 between mean individual biomass and density during densitydependentmortality (self-thinning). Empirical tests have produced variable results, and the validity of MST is intenselydebated. MST focuses on organisms’ internal physiological mechanisms but we hypothesize that ecological interactions canbe more important in determining plant mass-density relationships induced by density. We employ an individual-basedmodel of plant stand development that includes three elements: a model of individual plant growth based on MST, differentmodes of local competition (size-symmetric vs. -asymmetric), and different resource levels. Our model is consistent with theobserved variation in the slopes of self-thinning trajectories. Slopes were significantly shallower than 24/3 if competitionwas size-symmetric. We conclude that when the size of survivors is influenced by strong ecological interactions, these canoverride predictions of MST, whereas when surviving plants are less affected by interactions, individual-level metabolicprocesses can scale up to the population level. MST, like thermodynamics or biomechanics, sets limits within whichorganisms can live and function, but there may be stronger limits determined by ecological interactions. In such cases MSTwill not be predictive.

AB - Metabolic scaling theory (MST) is an attempt to link physiological processes of individual organisms with macroecology. Itpredicts a power law relationship with an exponent of 24/3 between mean individual biomass and density during densitydependentmortality (self-thinning). Empirical tests have produced variable results, and the validity of MST is intenselydebated. MST focuses on organisms’ internal physiological mechanisms but we hypothesize that ecological interactions canbe more important in determining plant mass-density relationships induced by density. We employ an individual-basedmodel of plant stand development that includes three elements: a model of individual plant growth based on MST, differentmodes of local competition (size-symmetric vs. -asymmetric), and different resource levels. Our model is consistent with theobserved variation in the slopes of self-thinning trajectories. Slopes were significantly shallower than 24/3 if competitionwas size-symmetric. We conclude that when the size of survivors is influenced by strong ecological interactions, these canoverride predictions of MST, whereas when surviving plants are less affected by interactions, individual-level metabolicprocesses can scale up to the population level. MST, like thermodynamics or biomechanics, sets limits within whichorganisms can live and function, but there may be stronger limits determined by ecological interactions. In such cases MSTwill not be predictive.

U2 - 10.1371/journal.pone.0057612

DO - 10.1371/journal.pone.0057612

M3 - Journal article

C2 - 23460884

VL - 8

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 2

M1 - e57612

ER -