Population density and size inequality in Galium aparine

The effects of density and time on the development of size inequality were studied for glasshouse populations of Galium aparine. The size of the first-emerging plant in each population was non-destructively measured (individual weight was estimated from height + branches length) and its growth rate was calculated. Destructive harvests were made 45 and 65 days after emergence. The growth rate of the first emerger was significantly affected by the presence of co-specific neighbours as compared with isolated plants. The weight of the first emerger was inversely related to the population density. The inequality of sizes was not affected by density or time but the interaction between these two factors was significant. Kolmogorov-Smirnov two-sample tests (applied on data transformed as a proportion of the maximum value) indicated that other attributes of the size distribution of the populations did change between densities. It is concluded that competition between G. aparine plants is a more symmetric process than in most plant species studied. The possible roles of leaf area distribution, shade tolerance and "intra-individual" competition on the degree of symmetry of intraspecific competition are discussed.