This tree is out of place!

40 Mile Scrub National Park (40 miles west of Mt Garnet) in Far North Queensland is a quick morning tea break for travellers heading west toward the more popular nearby destination Undara Volcanic National Park. If you have 5 minutes to spare, the 300m walking track loop through the scrub points out points of interest. Incoming AUSCCER PhD student Stephanie Toole and I are heading west from Cairns in search of Rubber Vine as part of AUSCCER research project ‘The Social Life of Invasive Plants’. Here we find Bottle Trees, White Cedars and Burdekin Plums.

The ‘scrub’ – dry rainforest or semi-evergreen vine thicket, is described as distinctly different to the lush coastal rainforests. Lower and more variable annual rainfall, combined with the hotter temperatures here limit and confines the distribution of its species to small mineral rich basaltic soil patches. Patches of rainforest in a sea of eucalypt savanna.

Some time ago, we learn, a seed, an interloper, survived and grew. ‘Out of place!’ this tree now stands as a mature narrow-leaved iron bark in the middle of the rainforest. What does it mean for a tree to be ‘out of place’? Can a gum tree be out of place in Australia? Where does this plant belong?

Plant distributions are governed by tolerances, competition and disturbance. Life is possible for different species across water, mineral and temperature gradients. Life must also contend with fire regimes, herbivory, competition and so on. If a seed sprouts and a plant grows to maturity – it is tolerant of the conditions and if it survives and reproduces – it is fit. Plants assemble themselves amongst and in the thick of things. How then can this tree or indeed any plant – life becoming through relations; exchanging gases with the atmosphere, feeding and sheltering inhabitants, rooted firmly in the ground – be out of place? Fit, but not fitting?

The rainforest savanna boundary is not a line marked in the sand, there is a transition zone, there are thicker and thinner edges. Disturbance and gaps in the canopy come and go, creating momentary opportunity for some. These zones of belonging change through space, and time.

No Rubber Vine in sight, we venture further into the scrub beyond the walking track. Instead, we find invasive species Lantana – thick, scratchy, impenetrable, rising over our heads, covered in ripening black berries. Wary of ticks, we head out, feeling a bit out of place.

 

Stamping on pests

‘Can you stamp on all the pest animals?’

Along the interpretive rainforest walk beside Lake Eacham National Park, part of Queensland’s Wet Tropics World Heritage site, children are asked if they can stamp on all the pest animals. Instructions clearly demarcate for anyone who might be unsure, exactly what to do – what is native and belongs, and what comes from other countries – and does not belong. The choice seems clear. With clear metaphorical intention, the game challenges children not only to learn to demarcate native from other, but as they do so, balance themselves on top of small constructed pedestals, stamping stones, each one identified by a picture diagram of possible friend or foe; Scrub Python, Indian Myna, Tree Kangaroo, Tilapia, Brush Turkey, Cane Toad, Goat.  We watch, and wonder, how each will choose; which animals to select and balance above, triumphant.

Today, with Stephanie Toole, I visited Lake Eacham along our route across the Atherton Tablelands, heading west toward the dry vine thickets and savanna country in search of invasive (pest) plant rubber vine as part of AUSCCER research project ‘The Social life of Invasive Plants’ led by Lesley Head. In this research we aim to provide new perspectives on human relations with invasive plants. We know they have significant economic and environmental impacts, but they have usually been studied from an ecological rather than a human perspective.

It shouldn’t be too hard to find –  rubber vine has infested some 700,000 hectares and is present across 20% of Queensland. It threatens pastoral production and significant tropical biodiversity. A formidable opponent; prolific, fecund, tenacious.

Stamping out Rubber Vine (resident in Australia since the late 1800’s) is one part of the national weed strategy – eradication in some parts of the country is part of the policy objective, but is it really feasible? How much is it going to cost? How long will it take? Is there an alternative(s)? What if it can’t be done?

In other parts of the country, vast tracts are heavily infested and eradication is not longer the objective. We look forward to learning what life is like for the people who have to live with – rather than stamp out this pest.