BIOMASS ALLOCATION IN A CLONAL VINE - EFFECTS OF INTRASPECIFIC COMPETITION AND NUTRIENT AVAILABILITY

Biomass allocation to roots, rhizomes, runners and climbing stems (i.e. twining axis and attached leaves) was studied in Calystegia sepium L., a clonal vine, In an experiment which took 2 months, nutrient availability (low and high) and intraspecific competition (none, shoot, root and both shoot and root) were manipulated. Under low nutrients the highest biomass of climbing stems was found in plants with shoot competition; the lowest was found in plants with both shoot and root competition. Total biomass under high nutrients was also greatest in plants with shoot competition. Thus, plants benefited from climbing up a shared stake rather than separate stakes. Larger plants allocated a higher proportion of biomass to runners in the nutrient-poor environment than in the nutrient-rich environment. This behaviour may increase the chance of finding nutrient-rich patches in the neighbourhood of the mother plant in a heterogeneous environment.