Thinning of swamp gum along the west boundary of ImLal South has successfully prevented them overwhelming the shrub layer. Five months after thinning the cassinia, hop plants and tree violets are thriving. Within this minimal intervention area, the plan is to alternate thickets of swamp gum with clumps of shrubs.
On our first Thinning Day, half a dozen people turned up with chainsaws for different sorts of thinning in three areas of ImLal South. It's six years since we established this site and we had always planned that this spring is when we ought to begin reducing competition between plants.
The first area was a no-brainer. A team of three cut down a swathe of 'volunteer' manna gums that had invaded one edge of the site and were growing up under a power line. One of the team followed up with a 50:50 mix of gylphosate and water, painting stumps, prevent coppicing. This was done in all three areas.
In the second area, another team halved the number of blue gums in the forestry block from 1,000st/ha to 500st/ha (see above). Those with the best form were selected to grow on.
In the third area to the west, we plan to minimise pruning and thinning. The plan here is to leave thickets of trees, but carve out open patches every 20-30m and remove invading trees where they are overwhelming shrubs. At one quiet spot much-loved by birdlife, we reduced the large number of swamp gums growing through everlasting shrubs, although leaving a screen of swampies for wind protection (see below).
You can view a gallery of pix on the Home page.
Over 20 students from Melbourne University's School of Ecosystem and Forest Sciences heard differing viewpoints from Phil Kinghorn and Gib Wettenhall on high or low silviculture of the biorich plantings. Senior Research Fellow Dr Lauren Bennett said later: "There was lively discussion on the return bus about the various issues that were raised, including comments on how instructive it was to see the reality of restoration practices, and how enjoyable the visit had been overall."
We just fled the hilltop in time as the wind rose and the rain fell. It was the day an extreme weather event caused massive outages in South Australia. Lauren concluded: "there were also comments on how well you (we) managed the weather (these admittedly made later as the rain set in)."
MU hopes to repeat the visit in coming years.
We have a split on the degree of silviculture that ought to be applied to the ImLal site – high or minimal intervention.
High intervention leads to ease of access, less perceived fire risk, reduction in tree density and the “pleasing prospects” approved of by explorers and pioneers in the days of Aboriginal land management.
Low intervention is closest to unmanaged natural forest and so-called “wilderness", as well as providing dense habitat for protection from feral predators like cats and foxes.
How do these two differing approaches affect biodiverse abundance (a primary goal of a biorich plantation). Seasonal bird surveys have tracked growing use of the site both in the number of species and size of flocks. To what extent will this be compromised by high or low silvicultural intervention?
We have agreed to divide ImLal South in half to demonstrate the use of both approaches.
It's been a very wet early spring. The 'footy field' has reverted to a swamp. What few plants survived from last October planting day are now underwater (see bottom right). We'd better stick to reeds.
Some 40 Gordon TAFE students from Geelong visited the ImLal site in August. After background from Stephen Murphy, Phil Kinghorn handed out pruning tools so the Conservation and Land Management students could gain some practical experience of an essential silvicultural skill. And it proved good vigorous exercise for a typically cold winter's day at ImLal.
This autumn's bird survey led to the largest number of species ever seen in a single survey - 30 different birds, with some of them in huge flocks. After a slow start, we found a sheltered spot with flowering swamp gums in a corner of ImLal South that was attracting a flock of mixed species small birds from honeyeaters to thornbills and wrens.
The dam treated us to the sight of a massive flock of over 120 wood duck, which rose to wheel above us. In the remnant, past the dam, noisy wattle birds and rosellas – again about 100 – drowned out the lone noisy miner.
The biorich plantation is well and truly coming into its own. A fuller write-up of this autumn feast of birds by survey leader, Grant Palmer, can be found under Monitoring.
Gib Wettenhall is interested in how we carry out large scale landscape restoration that involves the people who live in those landscapes. That, he believes, would build truly resilient landscapes.