Bacca quo vadis: Regeneration niche differences among seven sympatricVaccinimspecies on headlands of Newfoundland

Abstract

AbstractOn headlands in Newfoundland, four of the seven sympatricVacciniumspecies co-occur frequently at the quadrat level in tundra communities. We hypothesized that differentiation at the regeneration niche level was a prerequisite for the coexistence of these sympatric congeners. After a description and quantification of parameters affecting whole berry and seed dispersal and those affecting seed germination, differentiation at these two levels of the regeneration niches of the sevenVacciniawas investigated using numerical clustering techniques. Differentiation patterns were similar in both the germination and the dispersal dendrograms; three species were most dissimilar (viz.V. angustifolium, V. boreale and V. uliginosum), and the remaining four were separated into single species groups at the 62% and 75% similarity levels by the germination and dispersal dendrograms, respectively. Overall, patterns reflect divergence in dispersal mechanisms and germination abilities among the seven species, in support of the thesis that sympatric congeners have varied regeneration strategies. Differences in the germination success observed after testing natural dispersal units (e.g. seed from scat and seed within whole berries) points to the need to conduct germination trials in ecologically relevant ways. This approach reveals how divergent regeneration strategies are possible in species having similar, palatable baccate fruits (e.g.V. angustifolium and V. uliginosum) and highlights our lack of insight into regeneration strategies of the groups. The cranberry seeds, despite germination success gauged by results from standard germination protocols, exhibit no germination in trials conducted with the natural dispersal unit, the whole berry.