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.