Digger's Creek Bog, an
Empodisma minus–Callistemon pityoides–Sphagnum cristatum shrubby subalpine peat bog, alt. c. 1690 m, not far
below local altitudinal tree-line, began development > 10 000 years before
present as an Astelia
sp.–Carex alpine soak. Surrounding vegetation was
a grassy alpine herbfield with many Asteraceae, Apiaceae and
Gentianella diemensis, corresponding to the regional
Club Lake Zone C, dated to the same period. Astelia died
out c. 6500 years before present approximately at the
Club Lake C/D 1 boundary, marked by spread of
Pomaderris in subjacent montane forests. Thereafter,
shrubs, mainly Myrtaceae and Epacridaceae, and Restionaceae
(Empodisma and Restio australis)
dominated the bog. Epacris cf.
paludosa and C. pityoides seem to
have been the earliest shrubs to invade, Baeckea,
probably B. gunniana, and
Richea continentis reaching maximum prominence
5000–3000 years before present. Sphagnum was
uncommon until recently. Regional arboreal pollen enable comparisons with
other sites in south-eastern Australia but immigration of the tree-line
species Eucalyptus pauciflora subsp.
niphophila (snowgum) is not well expressed in the pollen
spectra. Surface and near-surface counts of this species are higher than at
any preceding time, and correspond most closely to surface counts in adjacent
young snowgum woodland. The co-occurrence of weed pollens, probably associated
with the late 19th and early 20th century practice of summer pasturing stock
on the alpine–subalpine tract, suggests that pasturing and burning,
responsible for widespread severe fires on this range, led both to the
formation of dense even-aged snowgum woodland that had been open and patchy at
this altitude, and a spread of Sphagnum on the bog
surface.
Transformation of Lake Ecosystem into Peat Bog and Vegetation History Based on Durne Bagno Mire (Lublin Polesie, E Poland)