Reports 2015-2016
Report for 12 November 2015 Meeting
Shade lovers
Some woody plants like wattles and turpentine flourish in the sun and fade away in heavy shade. But others shun the sun. Three shrubs that love the shade are white bolly gum, wilkiea and yellow pittosporum.
White bolly gum (Neolitsea dealbata) looks almost like a camphor laurel as a seedling, but it has a different smell and soon develops bigger leaves. It has periodic flushes of growth, producing lovely pink shoots with hanging leaves. Then it rests for a month or so, before producing another flush. Most rainforest trees have specialised insects and they prefer to chew on new, tender shoots. Having a spurt of growth (good for the insects) then a period of no growth (starvation) gives the insects a boom-and-bust time. It stops them from becoming a plague. Wilkiea (Wilkiea huegeliana) is another shade lover. In mature forest, it grows below the upper canopy together with white bolly gum. Both have fleshy fruits. These trees and fruit-eating birds like catbirds, bowerbirds and Lewin's honeyeaters depend on each other. The birds disperse the seed to new areas and the trees that result make them more suitable for the birds. Likewise, yellow pittosporum (Pittosporum revolutum) has bright red sticky seeds that birds disperse. All these shade-lovers need larger trees to shelter them.
Where the shade trees come from Why would birds spread seeds to a new area if it doesn't yet have their food trees? The answer may lie with kangaroo apple. Kangaroo apple is not a shade lover - it needs to be exposed to bright light and that's why it's so important. Clearing the weeds and exposing the soil stimulates kangaroo apple seeds to germinate. The seedlings grow rapidly, because they're fertilised by rotting weeds. By the second year after clearing they are providing a shrubby, fruiting cover. Birds love the fruits of kangaroo apple. They are attracted to them after feeding on the many rainforest fruits along the creek and that's why they come to poop rainforest seeds in the new area.
Shade management plan Clearing weeds works over a three-year management plan. Year 1 clearing exposes the soil in order to stimulate the germination of kangaroo apples. Year 2 brings in the birds to feed on the kangaroo apple fruits. Year 3 sees the kangaroo apples ageing, while lilly pillies, red ash and all kinds of vines are coming up, brought in by birds. And, as they grow, the saplings create a shady home for white bolly gum, wilkiea and yellow pittosporum.
Diary 21 Sep lyrebird seen on main track, Ray photographed wallaby and joey, echidna wandered by table at morning tea. 22 Sep Dan Keating (LLS) rang to report that RMS agreed to bush regen on border. 1 Oct Nikki Bennetts brought 500 nets and 1000 stakes. 7 Oct Christmas orchid flower spikes coming up. 8 Oct Kate Tuckson (Uni NSW) arranged student project (2 students). 13 Oct BDP interviewed by Kate Tuckson re attitudes of farmers and conservationists. 21 Oct webpage "see the forest grow" updated to include 2015 air photo. 23 Oct Andrew Robinson (Bushland Technical Officer, Kuringgai Council) visited to see progress. 30 Oct Paula Goodwin (legal agreement with RMS) phoned to report that agreement document had been passed to the legal department.
Report for 10 September 2015 Meeting
Just as pumpkins need more fertiliser than lettuces, so different native trees vary in their requirements for nutrients. They can be divided roughly into three groups -
Most greedy trees. These are all quick-growing rainforest trees that thrive when some disaster causes a gap in the forest. They have to grow fast before the gap closes up. Our best example is pencil cedar (right). On deep, fertile soil, it can grow at a prodigious rate. Other examples are red cedar and white cedar. All of them can survive as scrawny seedlings in mature forest. Then, should the neighbouring trees die, they quickly shoot up to fill the space.
Moderately greedy trees. These include most of the rainforest trees. Some are pioneers, like red ash, and these are eventually replaced by slower-growing species such as cryptocarias and cabbage palms. They also include the big blue gums and turpentines that regenerate best after a severe bushfire. These trees depend on many kinds of fungi that grow as a sheath around their roots. These fungi pop up now and again as toadstools. The fungi are more efficient than the tree at extracting the fertilising element phosphorus from the soil and they transfer it to the tree. In return, the tree supplies the fungi with sugars to grow on. We have a few places with hyacinth orchids. They steal the carbohydrate that's being supplied by the gum trees to the fungi. They're parasites, so they don't need any extra fertiliser or even leaves!
Least greedy trees. This group is a big one in Australia. They can grow on soils so poor as to be useless for agricultural crops unless fertiliser is added. The different species vary in their ability to grow on infertile sites. At the higher end, wattles transform nitrogen gas from the atmosphere to make their own nitrogenous fertiliser, although they do need small amounts of phosphorus. At the other end of the scale are the various banksia species. They are exceptionally efficient at extracting whatever tiny amounts of phosphorus can be got out of the soil. They live with microorganisms on their roots to help them do this. The level of phosphorus that is needed just to keep a pencil cedar growing is far too much for a banksia - it will choke on it and die.
These differences are important for rainforest regenerators, because weeds, whether privet, tobacco bush or black nightshade, are an invaluable resource, full of plant nutrients. Wattles don't need them, because soil and the air already supply wattles with more than they need. But greedy trees like the pencil, red and white cedars love to be mulched with weeds. As these rot, they liberate nutrients that will make the trees accelerate their growth, just as they do in mature rainforests where the surrounding trees have died.
Diary 9 July AGM and photo. 16 July 4 tonnes Bluemetal delivered by WSC. 20 July Vanessa Keyser visited (LLS) re grant proposal on RMS border. 27 July New member Robyn Nutley. 29 July Visit by Paula Goodwin (RMS Property Management), John Francis (RMS Roadside Maintenance), David Green (LLS) and Dan Keating (LLS) re grant proposal on RMS border. 6 August Group risk assessment with Penny Pinkess (WSC). 20 August Nikki Bennetts (WSC) delivered 500 plant guards & 1,000 stakes. 22 August Conducted 8 Joeys from Ourimbah Scouts around site with 2 supervisors. 3 Sep Samantha Willis (Water Watch) inspected creek bank for Year 10-12 students. 7 Sep ANSTO scientists checking tritium levels in well water to determine its age.
Report for 9 April 2015 Meeting
At the northern end of our site large-leaf privet is still producing seedlings. They are difficult to distinguish from seedlings of canthium (Cyclophyllum longipetalum), a native species that grows as a shrub or small tree in the understorey of the rainforest.
Canthium has a distinctive node, where the leaves join the stem. The opposite leaves are all in the same plane. In addition there are two tiny leaflets between the big ones. In fact canthium has four leaves at each node, although two them are very small, as the magnified image shows.
Privet, on the other hand, has opposite leaves with each whorl at right angles to its neighbours. And, as the magnified image shows, there is no tiny leaflet between the two large opposite ones.
Fortunately, you don't have to carry a microscope around to tell privet from canthium. If you tear a privet leaf into two halves, the upper skin of the leaf detaches readily from its lower skin. In contrast, the canthium leaf tears equally across both upper and lower skins.
Canthium has been christened "sweet Susie" presumably because of the strong perfume that the white flowers give off. The flowers develop orange fruits at this time of the year - reputed to be edible.
Diary 13 Feb Bird photos from Colette Livermore. 2 Mar Nicole Worrall and Liz More (Ourimbah School Landcare) visited. 3 Mar Robyn Urquhart (TAFE) with 6 students for plant ID. 4 Mar surveyed Transect 2. Penny Pinkess delivered 400 net guards and 500 stakes. EOI for freeway border work submitted to Vanessa Keyser (LLS).