Biology Reference
In-Depth Information
Box 2.1.
Leaf litter and invertebrates
Tree litter varies from tree to tree, and is a vital part of the ground layer. It includes
leaves, sticks, bark and dropped flowers and seeds from the canopy above.
9
Many
hundreds of species of microbes, fungi and invertebrates live in litter, breaking it
down and incorporating it into the soil. The larger invertebrates in tree litter are also
an important food source for reptiles, birds and small native mammals. Removing
litter takes away these attributes from a landscape. This means less biodiversity and
less food for birds, reptiles and mammals. The number of beetle species that can be
found in the leaf litter under
Eucalyptus
trees is amazing (Figure 2.2), and the differ-
ences in leaf litter under each eucalypt species can affect what species are found.
In a study of beetles under Blakely's Red Gum and Yellow Box trees, over 150
species of beetle were identified, with some species found under one eucalypt
species, but not the other.
10
All of these beetles are performing different ecological
functions: some are eating dead leaves and bark, some are preying on other inver-
tebrates, and others are eating fungus.
and trampling by domestic livestock, browsing by rabbits and kangaroos,
introduction of nutrients from fertiliser and stock camps, weed invasion, over-
abundance of exotic annual grasses, firewood harvesting, bush-rock removal and
raking leaf litter.
Overgrazing can lead to the loss of native orchids,
lilies, forbs (non-woody plants that are not grasses,
sedges or rushes) and cryptogams (plants that reproduce
by spores) from the ground layer.
3, 11, 12
It can reduce the
amount of native grass tussock cover which is a key
habitat component for a range of reptiles
7
and plays key
functional roles in ecosystems such as maintaining soil
surface condition and locking up soil nitrates thus reducing annual weeds.
13, 14
Temperate woodlands with an intensively grazed ground layer also appear to be
those most attractive to the Noisy Miner - a native honeyeater that aggressively
excludes many other species of native birds (see Box 2.7).
15
The widespread use of fertiliser and excessive nutrient enrichment from animal
dung represents another threat to the integrity of the ground layer of temperate
native woodlands. Areas subject to treatment with large amounts of fertiliser may
experience increased exotic pasture growth. The ground cover of many (although
not all) native plants can be significantly reduced, however, and some native plant
species can be lost. In contrast, exotic plant species cover and exotic species
richness is increased.
16 -19
An over-abundance of exotic annual grasses can
significantly impair habitat suitability for some native species of conservation
concern. For example, the Eastern Yellow Robin is rare in areas with extensive
Limiting overgrazing and
trampling by livestock,
and reducing fertiliser
application are two
important ways to manage
native ground cover
