Plasticity and Light Interception by Six Bryophytes of Contrasted Ecology

SUMMARY (1) Responses of six bryophyte species, of contrasted ecology, to controlled spatial and temporal patchiness in irradiance were investigated. Beams of unfiltered light projected into a shaded container provided standardized simulations of the effects of neighbouring foliage, litter or sunflecks. (2) The responses observed were consistent with the hypothesis that in plants of relatively productive habitats, high morphological plasticity in the rate and direction of shoot proliferation functions as a 'foraging' mechanism which allows resource acquisition in circumstances of localized resource depletion created by the activity of competing neighbours. (3) In bryophytes of shaded and chronically unproductive habitats, plasticity was found to be less pronounced; here the capacity to exploit sunflecks was shown to be important.