Want A Rainforest Garden? Then Plant Dry, Not Wet…

Queensland Lacebark, Brachychiton discolor
Queensland Lacebark, Brachychiton discolor

The word rainforest makes you think of hot, humid, dense, leafy, evergreen forest, such as the Daintree, the world’s most ancient rainforest in far northern Queensland (FNQ).

The Daintree is famous for its curious trees, ferns, palms, cycads, mosses, epiphytes, vines and orchids. FNQ is about tropical, wet rainforest but that  isn’t the only rainforest type.

Tasmania has cool temperate rainforest, the Sydney basin has warm temperate rainforest, and the Scenic Rim of Queensland has subtropical rainforest. Each different climate has produced its own version of rainforest, but each has a wet climate for at least some of the year.

For inspiration, the most diverse collection of wet rainforest trees grows at the Royal Botanic Gardens, Sydney. For many FNQld species, the RBGS is the most southerly location they are grown. Some specimens, such as Ribbonwood (Idiospermum australiense), are also the oldest or largest examples of their kind in cultivation.

The rainforest display at the National Botanical Garden in Canberra is a special place where rainforest plants thrive in a drier climate with a frosty winter. Here inspiration comes from they way they are grown in a hostile climate – in a gully, sheltered by trees and coddled by irrigation. That display is a fine example of how microclimates can be modified to suit special plant collections.

But what happens to wet rainforest plants during drought? They either need watering or they suffer, sometimes severely. Watering restrictions in the 1990’s made keeping the rainforest displays at the RBGS quite testing. Lacking fresh water bores, or stored rainwater, those rainforest displays didn’t always cope well with drought. It was tough for the gardeners who cared for those displays to watch them suffer when water was rationed.

Plant Dry Rainforest

When gardeners plan or plant a rainforest garden, a slice of the Daintree is usually what they visualise. One type of rainforest that seems to be almost always overlooked is dry rainforest.

If you haven’t knowingly seen dry rainforest, imagine  Hoop and Bunya pines rising through the canopy of a forest where trees have smallish leaves. Typically for rainforest, there are vines and epiphytes, including orchids, and ferns, but the canopy is lightly covered by foliage and the forest floor is sometimes well lit by sunlight.

Dry rainforest can be found quite some distance inland. On a scorching hot, sunny, dry summer’s day, it’s hard imagining Moree would be home for pockets of dry rainforest. Dry rainforests are also noisy places, they provide food and shelter for a wide range of wildlife.

The basket fern (Drynaria rigidula) and Elkhorn (Platycerium bifurcatum) have adapted to seasonal drought by dropping their fronds, remaining dormant until growth resumes after rain. Lichen too remains dormant until sufficient mist, fog or rain reawakens growth.

Some species are exceptionally rare, like the endangered Ormeau Bottle tree (Brachychiton ormeau). Several trees, like figs, shed their leaves to avoid dehydration during the hot, dry, windy springs and the long wait between brief, wet summers. Leafless Brachychiton trees also flower, often spectacularly. The Crown of Gold, (Barklya syringifolia), the town of Gladstone’s floral emblem, is another spectacular flowering tree.

For the gardener, the benefits of growing dry rainforest plants are they are more forgiving, need less water, and can be more colourful in bloom. Little Kurrajong and Crown of Gold are ideal flowering trees to develop a suburban dry rainforest garden. Dry rainforest species establish faster if well watered, however they are more drought-resistant if watered sparingly. Once established, dry rainforest species survive longer, hotter, drier spells and erratic rainfall better than wet rainforest.

So why not plant a dry rainforest instead? Some plants are already familiar, like macadamia, bunya and finger lime. (Yes, these species also occur in wet rainforest. Rainforest is more complicated than most of us realise and dry rainforest especially so).

When I worked at the RBGS, we highlighted differences between Australian rainforest types. Community Education and sometimes I offered interpreted tours to schools, VIP’s and the Friends of the RBGS. Here’s some of our interpretive information on drought-tolerant, water saving, dry rainforests:

Dry rainforests

Not all rainforests grow in areas receiving evenly distributed, abundant supplies of rainfall. Lesser known are the tiny remnants of Dry Rainforests scattered across the Kimberley, Top End, Cape York, and down the east coast of Australia. In NSW, patches occur inland to the Moree region over 400km from the coast.

Gargaloo, Parsonsia eucalyptophylla (Apocynaceae), a dry rainforest vine growing in Yapunyah, Eucalyptus ochrophloia, west of Moree, NSW.

Since they occur in regions with a distinct wet and dry season, the more northerly monsoonal forests survive in sheltered gullies and along the banks of rivers. Under moister, past climatic conditions, their ancestors were widespread across the continent. As the climate became less suitable for rainforests, those species best fitted for the arid conditions survived. They replaced species less able to survive in the new conditions and evolved to deal with the changing environment.

Along the east coast, marginal rainfalls or poorer soils support Dry Rainforests in sheltered locations. They often grow on rocky sites that are rarely subject to fire. Because some Dry Rainforest trees have a greater tolerance of arid conditions, communities can be found up to 300 km inland where suitable shelter exists.

The ability of some species to shed leaves in dry conditions is an advantage for Dry Rainforest trees, enabling them to survive temporary water shortage. Common species include Lacebark (Brachychiton discolor), Australian Teak (Flindersia australis), Hoop Pine (Araucaria cunninghamii), and figs (like Ficus superb var. henneana).

Characteristic features of dry rainforests

* Small to large number of tree species forming the low to medium canopy layer;

* Scattered, larger trees, with emergents rising above the canopy;
* Trees include semi-deciduous species, like (Brachychiton species, or Leichhardt bean, or conifers (Callitris species);
* Small average leaf size of canopy trees. Leaves are often hard and blunt-tipped;
* Palms are absent;
* Large vines are common and diverse;
* Vascular epiphytes (flowering plants, like orchids) either rare or common, but with few species;
* Mosses and ferns are scarce, but lichens are abundant;

 

Relictual Dry Rainforest, Moree
Relictual dry rainforest, Moree.

Last autumn, I visited the Quaker Arboretum which participates in Open Gardens Australia, to see how their collection of dry rainforest plants is coping after two dry years (2013, 2014).

That garden is looking great. It’s certainly dry, but all the plants are coping well. They are mulched, but receive no irrigation.

Here is a consolidated list of Dry Rainforest Species, your introduction to the diversity of Australia’s mosaic of dry rainforest communities, many of which can be obtained from Kumbartcho Nursery.

Cassia brewsteri, Leichhardt bean.

I’ve included a gallery of dry rainforest plants. Surprisingly, there are more beautiful blossom trees in Australian dry rainforests than in our wet rainforests.

If you want a successful rainforest, one that will stand the test of time and our continually surprising climate, plant dry not wet rainforest species.

Jerry Coleby-Williams

18th March 2014, revised 12th August

 

9 Comments Add yours

  1. grant says:

    Hi Jerry, I have just stumbled upon information about Crown of Gold, (Barklya syringifolia) today. Searching for this plant online is what bought me here. I was wondering if you know who would be the best nursery in the brisbane region to purchase this plant from. I have not been able to locate anywhere online. Any recommendations would be greatly appreciated.

    1. Kumbartcho Sanctuary and Nursery, Eaton’s Hill. They have twice been interviewed by me on my 4BC Radio programme, Sundays 7-8.30am. Jerry

  2. Andrew Kopp says:

    Great article, glad someone is promoting Dry rainforest it is perfect for our damaged urban landscapes. I always remember the Mallotus philippinensis and Jagera pseudorhus growing Kumbarcho when I think of Dry rainforest.

  3. Sue McNamara says:

    Hi, I purchased 11 trees/shrubs at today’s Ecofest in Gladstone to start a dry rainforest. I have a very rocky hillside, & have left some of the regrowth (trees) grow. What is best to use as in potting mix/soil? I have scattered dolomite. Is there anything else I need to help improve the area before I plant. Would appreciate your advice

    1. Why add dolomite? Have you chosen species than cannot cope with local soil and conditions? Plant in local soil and mulch.

  4. geoff says:

    Great story Jerry Im developing DRF in a Toowoomba council gully with a soak to reduce fuel load, increase biodiversity and make the place look better. Replacing african pasture grasses and lantana with Lomandra and a range of attractive natives is working well after a couple of years with lots of council mulch. Old records talk of the springs supporting rainforest surrounded by Forest red gum and someone had planted a couple of figs (Benjamanii!), Broad leaved Tuckeroos and firewheels that gave me hope. There are too many attractive DRF natives to fit in but the early standouts are native frangipani, Pittosporum undulatum and P. rhombifolium, Senna acclinis, deep yellow wood, red cedar, creek sandpaper fig, Ficus rubiginosa, F. watkinsiana, Small leaved tuckeroo, tulipwood, beetroot and silver croton. Looking to increase the flowering shrubs such as Brachychiton bidwillii and Sophora fraseri along paths.
    Any thoughts on a native fruiting tree to fill bird food gap in August/September ? – putting in some Jagera, Grevillea robusta and Coogera (very slow!)

    1. ‘Fruit’ in spring follow flowers in winter, so head to Acacia. Or look to spring flowers with nectar, like Eucalyptus tereticornis or Melaleuca leucadendron, Queensland’s two most important habitat species.

  5. Thanks for this wonderful article . I’m currently planting trees and shrubs for the extraction of their useful chemicals . I never realised Australian plants had so much potential for their useful compounds. Maybe you could do a story on this down the track . Thank you

  6. Those are beautiful trees. I hope those are preserved for many years! By the way, It’s a great written content and its very informative, all your shared images are great. Thanks!

Leave a Reply to geoff Cancel reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.