In a generally dry continent, waterways are especially important habitats. Obviously, they are the only habitat for freshwater aquatic life, but their surrounding land—the ‘riparian zone’ is highly productive habitat as it has more moisture and nutrients than non-riparian country.
As our climate warms and generally dries, waterways are increasingly important as refuges during droughts. Campbells Creek, unlike most of our local waterways, has permanent water flows (downstream from the waste water treatment plant) and with good management should serve as a very valuable habitat resource. We know it already supports populations of the aquatic ‘top’ predators, platypus and rakali (native water-rat). These species couldn’t exist without their food species being present, so indicate that Campbells Creek already plays an important role.
However, much of the creek and surrounding land remains in a very degraded condition following the devastation of the 1850s gold rush.
The following segments describe what we’re doing about it.
We are gradually restoring native vegetation cover to the land over which we work. This is important for several reasons. Land without native vegetation has very little habitat value and supports few species. Replacing weeds with native plants increases habitat values and, over time, can re-establish much of the missing resources for our native fauna. Of course, some of this may take centuries: that’s how long it takes for hollows to form naturally in trees.
Native vegetation cover also protects the land from erosion, salinity and soil acidification. These are all common land degradation processes in the local landscape.
Tree cover along the creek helps shade and cool the water, allowing higher oxygen content in summer and helping prevent toxic blue-green algal blooms. In our patch, algal blooms used to occur every late summer and early autumn during years of low rainfall and stream flow.
Leaf fall from native trees and shrubs also provides year round food supplies for the invertebrates that are the food supply for platypus, rakali, fish and other predators.
A 2018 survey of aquatic macro-invertebrates in Campbells Creek showed surprising high populations and diversity, showing that these animals can return, given a chance.
Many species disappeared from our patch following the massive disturbance of the 1850s gold rush, subsequent clearing and conversion of land from wild bushlands to agricultural uses and the introduction of invasive species. Some species have never reappeared and are extinct in our district or completely extinct.
We work at re-introducing plant species known or thought to be indigenous to our area. Over time, we hope that the habitat resources we create will encourage the return of fauna species as well.
We have re-introduced over 100 plant species and more than 40 now exist as self-sustaining populations, i.e., they are reproducing new individuals from parent plants that we established.
Some of the more notable successes are listed below. All these species now are recruiting new plants from seed:
Natural tree hollows are in extremely short supply in our district as almost every tree was felled in the 1850s gold rush. Any remnant old trees in the public land forests were deliberately targeted for removal during 1930s depression employment programs that government foresters organised to encourage growth of young trees and marketable timber. Wild fires often burn out old, hollow trees.
From time to time, we install nest boxes in the hope that hollow dependant fauna may take up residence.
Some of the local hollow dwelling species already known to occur along the creek are:
Invasive plant species are one of the biggest threats to the habitat values of the urban waterways. Before restoration work started in 1986, most of the creek-sides were dominated by blackberry or willow. Away from the water, much of the public land was infested with gorse. Those three species are regarded as ‘weeds of national significance’ (WoNS) because the damage they cause to Australian environments is so widespread and severe. Other WoNS species present in our patch are:
- African Boxthorn
- African Boneseed
- Bridal Creeper
- Wheel Cactus
- Cape Broom
- Flax-leaf Broom
- English Broom
- Montpellier Broom
- Chilean Needle-Grass
We have infestations of many other declared noxious weed species and even more species of ‘environmental weeds’, i.e., invasive plant species without legislative or other status.
Our targeted weed control program is based on the idea of eradicating new and emerging weed species from our patch and reducing priority weeds to levels where they no longer have significant environmental impacts.
From our patch we have eradicated (as far as we can tell) the following invasive species that were new/emerging.
- Creeping or perennial thistle (Cirsium arvense)
- Californian stinkweed (Navarretia squarrosa)
- Reedmace (Typha latifolia)
We are still working on eradication of Reed Canary-grass (Phalaris arundinacea). This species is a potent wetland invader, only recorded in one other place in north central Victoria.
We have now succeeded in reducing blackberry to insignificant levels along the creek-sides, and gorse is no longer a major problem on the creek-side public land, though still a major issue in Honeycomb Bushland Reserve. Both these species require annual monitoring and follow up on new infestations that recur in previously clear areas.
With the help of the Department of Environment, Land, Water and Planning and Mount Alexander Shire Council we are also making great progress on reducing the willow infestation.
Apart from priority species we target, we are also attempting to replace weed cover with native vegetation. This replacement program is having good success along the moister low lying land using the large tussock grass Poa labillardierei. Other native species with the same ‘large robust tussock’ lifeform (like sedges and rushes) are also proving very useful. Once established, native trees and shrubs also help out compete weeds.
We also need to control competing weeds in preparation for revegetation work.
All our weed control work is done using best practice methods. Where this involves herbicide, application is done by accredited contractors or our own volunteers who possess agricultural chemical users permit certification.