Within the high subalpine tract of the Bogong High Plains there has been a gradual increase in the cover
of shrubs over the past 40 years, especially within open heathland and grassland communities. A field
trial, using permanent 1 m2 plots, has confirmed that the establishment of shrub seedlings such as
Asterolasia trymalioides, Grevillea australis, Phebalium squamulosum and Prostanthera cuneata occurs
primarily upon bare ground, and is absent where the cover of vegetation or fixed Poa hiemata litter
remains intact. The survival of Poa hiemata seedlings on bare ground is low, except where local shelter
is afforded. Disturbances which cause bare ground, including domestic cattle activity, can create
microsites suitable for the establishment of shrub seedlings. Shrub establishment and development may
be inhibited by cattle trampling, and some palatable shrubs, e.g. Asterolasia and Grevillea, are especially
affected. If cattle are removed from previously grazed grassland and heathland sites where shrubs such
as Asterolasia and Grevillea have established, the encroachment of such shrubs will be more rapid than
on similar sites subject to continued grazing. However, continued cattle activity is unlikely to inhibit
the development of non-palatable, vegetatively reproducing shrubs such as Prostanthera cuneata and
Phebalium squamulosum within closed heath communities.
The Trans-Alaska Pipeline System Facilitates Shrub Establishment in Northern Alaska
