Use of the Lorenz curve to measure size inequality and growth dominance in forest populations

Devised in 1905, the Lorenz curve was used initially to study inequality in income distribution in human populations. Its principles have been adapted to provide measures of the size inequality between individuals in plant populations and to assess the degree to which plants of different sizes tend to dominate growth within the population. This work describes the principles on which these measures are based and the various mathematical methods available to determine their values. The potential for their use in forest populations is illustrated with an example describing their changes with age within a plantation forest stand and how these relate to inter-tree competitive processes within the stand. It is concluded that these measures have considerable value in studying the structure and growth behaviour of forest populations.