Chapter

Disturbance in Grasslands

Volume 10 of the series Geobotany pp 237-252

A physiological analysis of genotypic variation in relative growth rate: Can growth rate confer ecological advantage?

  • H. Lambers
  • , P. Dijkstra

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Abstract

Species from contrasting habitats differ in their relative growth rate (RGR) (Grime & Hunt, 1975). Species from nutrient-poor, acid soils, e.g., Agrostis setacea and Deschampsia flexuosa, tend to have inherently low growth rates compared with species from nutrient-rich sites, e.g., Agrostis stolonifera and Urtica dioica (Clarkson, 1967; Rorison, 1968). A frequently quoted paper to support this contention is that by Bradshaw et al. (1964). However, these authors measured yield, rather than growth rate, of a number of species from rich and poor habitats. Differences in final yield may simply reflect differences in initial size, or differences in the duration of the maximum relative growth rate, as demonstrated by Van de Dijk (1980) in his work on two subspecies ofHypochaeris radicata, one from a fairly nutrient-rich roadside, the other from a poor heathland. For this reason, and also since RGR may show ontogenetic drift (Van Andel & Jager, 1981), a careful growth analysis, rather than only one harvest, is required.