Cha. Wahren et al., Vegetation change and ecological processes in alpine and subalpine Sphagnum bogs of the Bogong High Plains, Victoria, Australia, ARCT ANTARC, 33(3), 2001, pp. 357-368
Sphagnum bogs that were monitored over a 15-yr period showed significant ch
anges in the abundance of diagnostic species. At plots ungrazed by cattle,
the major bog species Sphagnum cristatum, Caltha introloba, and Carex gaudi
chaudiana increased significantly in cover. No such increases occurred in g
razed plots. There were few changes in cover of the main structural vegetat
ion types-closed heathland, low open heathland, and open herbfield on stony
pavements. Sphagnum and the main herbfield species, Oreobolus pumilio and
Caltha introloba, were dislodged and shifted over unvegetated stony pavemen
ts by snowmelt runoff, snowpack movement, and cattle trampling. Experiments
using Sphagnum transplants showed this species capable of colonizing pavem
ents by establishing on other plants. Survival and growth of transplants we
re significantly greater on low compared with high water flow (high energy)
sites. Grazing and trampling by cattle significantly reduced survival of t
ransplants. thus disrupting the colonization of pavements; firstly, by dire
ctly reducing the survival and growth of Sphagnum and other colonists; and
secondly, by preventing the formation of barriers to water flow that would
facilitate colonization. We propose a successional dynamic based on some of
the processes operating in the open herbfield and stony pavements of Sphag
num bogs.