The 2021 planting season kicks off

March and April saw us receive some of the best soaking rain we have had in years. I can’t even remember the last time we had above-average rainfall for two consecutive months. While no one day had particularly heavy falls, consistent showers, spread over many weeks, has thoroughly soaked the soil profile. Our dam is full and our creek has been flowing for many weeks. Both are currently packed full of tadpoles and, even though it’s only been one month, the first of the next frog generation has already started to emerge.

Hundreds of newly emerged frogs (probably Graceful Tree-frogs, Litoria gracilienta) adorn the small trees I have planted beside our dam. This Drypetes leaf is only 5 cm wide. The young frogs lack the green colour of the adults, so they are not at all well camouflaged. I’m amazed the local herons haven’t discovered them yet.

Unsurprisingly, with all the frogs that have been about over the past year, I have noticed more Green Tree-snakes than ever. This one was spotted this week climbing up our patio in search of Green Tree-frogs sheltering in the gutters and down pipes. It’s impressive how they can scale vertical surfaces like this.

Green Tree-snake, Dendrelaphis punctulatus

One animal that has not returned with the wet weather is the European Garden Snail, Cornu aspersum. When we moved in five years ago, there were hundreds of these introduced snails inhabiting the gardens around the house. I suspect that Pine Mountain was always a marginal climate for this temperate species, as I never found them away from the house, where they had access to supplementary water. However, during the 2019-2020 drought, they disappeared. Even after a couple of months of wet weather, the only signs that the species ever existed locally are the long-dead shells of drought victims. It is not often I’ve witnessed a local extinction worth celebrating.

A ghost of wetter times past

After two dry autumns in which unfavourable weather prevented me from planting all my nursery stock, I have been desperately and hastily trying to get as many trees in the ground as possible. The opportunity to finally empty my nursery, and relieve myself of the daily burden of watering about 1,000 trees that had long ago outgrown their pots, is one I dare not miss. So far, I’m about half way.

The race to get trees in the ground has not only been dictated by the recent wet weather. Over a period of just a couple of nights, a Black Rat (Rattus rattus) decided that the overgrown nursery was the perfect place to set up house. The destructive bastard made a total of five nests (one on every shelf) by chewing off the foliage and then the main stems of a good portion of my trees. Many of these seedlings were two to three years old, but were reduced to stumps in a matter of days. After I dismantled all the nests and hosed the rat, it eventually fled and did not return. In ten years of growing my own native plants, this is the first time I’ve had to contend with a nesting Black Rat, and I wonder if it is a symptom of my nursery being packed too densely with quite advanced stock.

One nursery pest I have to contend with every autumn is longicorn beetles. These beetles chew the bark off in characteristic rings and lay their eggs above the cuts, so that the larvae can burrow into the dying branch. They favour soft, growing branches that are just under 1 cm diameter. This means that in the bush they usually attack the outer twigs, and cause no lasting damage to their host trees. However, in my nursery they ring-bark seedlings right near their base, killing the entire stem. While the plant typically reshoots from below the cuts, it still means that one or two years of growth is lost, which is particularly frustrating when this happens in autumn, just as I’m about to plant the trees out. I always keep a close eye on my seedlings at this time of year, in order to find any beetles that sneak into the green house.

Unknown species of longicorn beetle, from the sub-family Lamiinae. This poor Mallotus philippensis had already had its upper twigs chewed off by the Black Rat. Unfortunately, by the time I noticed the beetle, it had already made multiple rings through the bark. The beetle was escorted out of the green house to a more suitable adult tree.

To misappropriate the Bible, Nature not only taketh away, but giveth too. The rack of seedlings in the photo below were all potted up from the garden surrounding our bird baths following the recent rain. A dozen species of local rainforest trees and vines delivered for free, courtesy of our local Lewin’s Honeyeaters. They will all be moved to more suitable homes in the bush next year.

Freebies from our local birds

In other favourable nursery-related news, my attempts to attach the local root-parasitic tree Exocarpos latifolius to a host plant have been successful. This is a plant that has proven difficult to cultivate. I managed to germinate two seeds, but they languished in their own pots for over a year without growing more than a couple of (very yellow, malnourished) leaves. It is a species that extracts much of its nutrients from the roots of other trees, but surprisingly little is published about which host species they are able to utilise. I decided to try planting them in a large pot with a different host species each. I selected species that don’t grow too large (I didn’t want them to shade out the E. latifolius) but which are long-lived (providing a stable source of nutrition). For the first year that both E. latifolius were with their hosts, the two host plants (Citrus australis and Everistia vaccinifolia) rapidly grew to fill their large pots. However, the Exocarpos did not grow a single leaf! One of the E. latifolius (the one with Everistia) still hasn’t grown a single leaf, and it has now been with its host for 18 months. The other, meanwhile, suddenly started to grow a couple of months ago and has evidently attached to its Citrus host. I will plant both out in the coming weeks, so hopefully the unsuccessful one will find some other root on which to attach.

The Exocarpos latifolius growing on the left with Everistia vaccinifolia is the same yellow, malnourished runt as it was 18 months ago, while the one on the right with Citrus australis has begun to grow rapidly.

The wet weather has meant that the local vine-scrubs are looking as healthy as they’ve looked in years. The cooler weather has also meant that the usual hordes of caterpillars that attack new growth over summer are absent. My planted trees are putting on substantial growth for the first time in almost two years. Many of them are also fruiting for the first time, including the following.

I had always thought of Vitex lignum-vitae as slow-growing, but three individuals, each only fours years old, are currently fruiting for the first time.

Both the wild and my planted Auranticarpa rhombifolia are fruiting heavily this year. Despite the tiny arils at the base of each seed offering little in the way of food for birds, both Lewin’s Honeyeaters and Silvereyes still eat them.

Stephania japonica is probably not a vine I would have planted again among such young trees, as they grow so vigorously they can smother the other plantings. Still, they produce a great tangle of foliage for scrubwrens and other birds. I’m just careful to trim them back from any particularly valuable trees.

One locally native tree that I never plant, but which dominates our property, as it does everywhere the original rainforest has been cleared or otherwise disturbed, is the Hickory Wattle, Acacia disparrima. This large, long-lived wattle does not germinate within intact vine-scrub, as it requires strong light at ground level. However, it readily recolonises cleared paddocks, roadsides and burnt areas. I find that they tend to retard the growth of rainforest trees growing beneath them. As my aim is to restore a mature vine-forest plant community (which generally lack this species) as rapidly as possible, I don’t want to plant more of this species than we already have. Acacia disparrima is currently flowering after the autumn rain.

With relatively dull flowers for a wattle, the most characteristic feature of Acacia disparrima is their blue-grey foliage that forms dense canopies on local hillsides where the forest is regrowing after past disturbance.

Another feature of autumn and, locally at least, always associated with Acacia disparrima are Processionary Caterpillars, Ochrogaster lunifer. Large colonies of these hairy beasts live in webbed nests at the base of a tree, climbing into its crown to feed at night. However, when their food supply becomes exhausted, they march out in single file caravans in search of a new tree.

Processionary Caterpillars, Ochrogaster lunifer

It is only within the last ten years that veterinarians at the University of Queensland discovered that the itchy hairs of these caterpillars are one of the main causes of a condition in horses known as Equine Amnionitis and Foetal Loss (EAFL). EAFL causes birth defects in foals and miscarriages in horses, and is responsible for up to one third of abortions in the Australian thoroughbred industry. Horses incidentally ingest the irritating hairs from the discarded exoskeletons of these caterpillars when eating grass. If you are wondering (I was) how scientists made the connection between Processionary Caterpillars and horse miscarriages, the gruesome method was by force-feeding pregnant mares with a “slurry of shed processionary caterpillar exoskeletons by nasogastric intubation”. It is unclear why horses appear to be particularly vulnerable, or whether other mammals may also be affected. Still, if you are a local horse breeder, it would be prudent to remove any Acacia disparrima from your paddocks. Alternatively, keep a close eye on any large silk nests forming at their bases and remove these early. For the rest of us, these curious trains of moth larvae that march across our lawns, forests and roads each autumn make for an interesting sight.