BRANCHING AND COMPETITIVE HIERARCHIES IN POPULATIONS OF GALIUM-APARINE

The role of branching on the development of size hierarchies was studi ed on experimental populations of the annual herb Galium aparine L. (R ubiaceae). All branches of plants growing at high and low density were severed as plants developed, and the growth of individual plants, the development of growth and size inequalities, and the mean change in t he size ranking of plants over time were compared with those of popula tions of naturally branched plants. Size allometries were analysed for all treatments. The effect of the branch-severing treatment on growth and size inequalities was not significant for crowded populations. Th e position of individual plants in the ranking of weights in crowded c onditions was less variable for populations of unbranched plants than for those of branched plants. Size and growth inequalities among branc hed plants were not significantly affected by population density. The hypothesis that branching increases the development of competitive hie rarchies in G. aparine populations is not supported by the results. Th e role of height growth limitation in crowded conditions as a constrai nt to competitive hierarchy development is discussed.