TY - JOUR

T1 - Partitioning the components of relative growth rate

T2 - how important is plant size variation?

AU - Rees, Mark

AU - Osborne, Colin P.

AU - Woodward, F. Ian

AU - Hulme, Stephen P.

AU - Turnbull, Lindsay A.

AU - Taylor, Samuel H.

PY - 2010/12

Y1 - 2010/12

N2 - Plant growth plays a key role in the functioning of the terrestrial biosphere, and there have been substantial efforts to understand why growth varies among species. To this end, a large number of experimental analyses have been undertaken; however, the emergent patterns between growth rate and its components are often contradictory. We believe that these conflicting results are a consequence of the way growth is measured. Growth is typically characterized by relative growth rate (RGR); however, RGR often declines as organisms get larger, making it difficult to compare species of different sizes. To overcome this problem, we advocate using nonlinear mixed-effects models so that RGR can be calculated at a standard size, and we present easily implemented methods for doing this. We then present new methods for analyzing the traditional components of RGR that explicitly allow for the fact that log (RGR) is the sum of its components. These methods provide an exact decomposition of the variance in log (RGR). Finally, we use simple analytical and simulation approaches to explore the effect of size variation on growth and its components and show that the relative importance of the components of RGR is influenced by the extent to which analyses standardize for plant size.

AB - Plant growth plays a key role in the functioning of the terrestrial biosphere, and there have been substantial efforts to understand why growth varies among species. To this end, a large number of experimental analyses have been undertaken; however, the emergent patterns between growth rate and its components are often contradictory. We believe that these conflicting results are a consequence of the way growth is measured. Growth is typically characterized by relative growth rate (RGR); however, RGR often declines as organisms get larger, making it difficult to compare species of different sizes. To overcome this problem, we advocate using nonlinear mixed-effects models so that RGR can be calculated at a standard size, and we present easily implemented methods for doing this. We then present new methods for analyzing the traditional components of RGR that explicitly allow for the fact that log (RGR) is the sum of its components. These methods provide an exact decomposition of the variance in log (RGR). Finally, we use simple analytical and simulation approaches to explore the effect of size variation on growth and its components and show that the relative importance of the components of RGR is influenced by the extent to which analyses standardize for plant size.

KW - Growth analysis

KW - Nonlinear mixed models

KW - Relative growth rate

KW - Variance decomposition

U2 - 10.1086/657037

DO - 10.1086/657037

M3 - Journal article

C2 - 20950150

AN - SCOPUS:78649697371

VL - 176

SP - E152-E161

JO - The American Naturalist

JF - The American Naturalist

SN - 0003-0147

IS - 6

ER -