Somatic costs of reproduction in eight subarctic plant species [Abisko]

The reproductive effort and relative somatic costs were quantified in terms of biomass, nitrogen, and phosphorus for 13 plant populations representing eight species in a subarctic environment, Swedish Lapland. Reproductive effort varied about fivefold between populations (from ca 0.1 to 0.5). Correlations among reproductive effort in terms of biomass, N or P and among relative somatic costs (same resources) showed that the allocation of one resource closely reflected the allocation of another resource. Reproducing plants generally incurred somatic costs of reproduction measured as decreased somatic resource pools after one season's reproduction. Reproductive costs were generally of similar magnitude as the corresponding reproductive effort in terms of N and P, and lower than reproductive effort in terms of biomass. Thus, there were general compensation mechanisms for reducing somatic costs in terms of biomass. Differences between investments and costs were also found for some species in terms of P. For species studied at two altitudes, the reproductive effort and somatic costs were in most cases highest at the low altitude.