Carbon relations and competition between woody species in a Central European hedgerow : IV. Growth form and partitioning.

Growth of woody species has two components, one pertaining to increment of biomass, the other to the architectonic arrangement of dry matter in space. Only the combination of both components explained the competitive strength of species that dominate in different stages of a hedgerow succession in Central Europe. Biomass increment was measured using an empirical volumetric method, and plant architecture was investigated from branching patterns which determined the growth form of species. Assimilate partitioning was determined from total plant carbon gain and biomass increment in different above-ground plant parts. Those species with lower dry matter, nitrogen, and phosphorus costs for occupying and shading space during canopy development were the stronger competitors and replanced pioneers, even though their rate of CO2 uptake was low. Ecological implications of different partitioning patterns for the survival of a plant and for successional changes in vegetation are discussed.