Theil’s inequality index applied to quantify population variation of plants with regard to dry matter allocation

The inequality index of Theil (1967) was initially developed to calculate income inequality in human populations. It is applied here to determine the per organ dry weight variation in plant populations and integrated to an index of population variation (IPV). The weight fractions used to calculate the IPV are further used to calculate an allocation index (AI) for each plant member of a population. The method implicates the possibility to reconstruct the relative contribution of each organ (or individual) to the overall indices of the population, thus smoothing the way for a further interaction between population ecology on the one hand and ecophysiology and ecogenetics on the other. Some applications of the method are given and discussed with regard to the need to evaluate and improve various concepts of evolutionary strategies.