Cape Tribulation Research Station and Reforestation

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CAPE TRIBULATION RESEARCH STATION

There’s a lot more to rainforest revegetation work than digging holes and planting trees. When Hugh Spencer and his wife Brigitta bought a cleared block of land in the Daintree 33 years ago and decided to re-create a forest, they were embarking on a project that has become a reforestation model for the region. The tallest trees are now over 20m high and the new forest covers six hectares.

Here are some of their learnings, as landholders and as founders of the Cape Tribulation Research Station and Australian Tropical Research Foundation.

Hugh says:

Work the way nature would work:

It’s important to use local plants which have evolved in your area. Be flexible – nature doesn’t plan the composition of forests. It is dependent on available seeds and the vagaries of the seed dispersers.

Use local seedlings:

We collect seedlings alongside roads or on the boundaries of forests. (Nature has done the hard work of germinating them but nature is profligate, and many won’t survive there because they’ll be shaded out and outcompeted, or they’re just in the wrong place.) We pot them, look after them with shade and water, and let them develop. After six months we start the hardening process and we plant them in the ground once the heavy rains start.

Use local soil:

We discovered early on that nursery mix didn’t work here. The plants were drying out incredibly fast as we didn’t have the luxury of spray irrigation. We plant our seedlings about 1.5m apart. It takes a little longer to get a closed canopy but …

Weed control:

Highly invasive weeds have the potential to prevent re-forestation of damaged land. Weeds were the biggest issue for the first 10 or so years. We were up against introduced species including guinea grass, Brachiaria, navua sedge and sicklepod. We stomped (to flatten) and sprayed grasses,
with glyphosate and they became thick mulch beds. This greatly reduces weeding and conserves soil moisture. We also used metsulfuron-methyl (MSM), a selective broadleaf herbicide and discovered it was the best answer to much of our weed control issues.

In trials, volunteers at the station assessed the impact of MSM weed spraying on seedlings of the native flora and found that 85 per cent of the native rainforest species (78 species were tested) exposed to metsulfuron-methyl were unaffected or, after a minor setback, recovered. Most of the 15 per cent of species affected were pioneer species.

Trial and error was part of the process:

We originally planted pioneer species like bleeding heart (Omalanthus) and Macaranga. This was a mistake. Bleeding heart is short-lived – about five years – and Macaranga lasts about 10 years. We tried red cedars too and they all died. We discovered the soil here isn’t good for fruit trees (without lots of fertiliser) but our native plants do very nicely. We plant species quite randomly, using which-ever native seedlings we can get, which is exactly what happens in nature.

Be patient:

It took three years to get something that resembled canopy closure. We were lucky to have had many volunteers at the station who helped with planting, propagating, stomping weeds etc. Over 30 years, we’ve probably had about 1000 volunteers and students visit us from all over the world. They stay for anything from 10 days to a month and they’ve helped a lot, and also undertaken research here on pollination, weed control and littoral rainforest to name some topics.

Working methodically helps:

We have an L-shaped block. We started at the road and moved west. We did strips of revegetation when we could – and not too much at one time because getting wildly enthusiastic can lead to things getting out of control when it comes to watering the trees and managing the weeds. Extending out from a boundary with existing rainforest is also a good idea, as the boundary area will supply seeds and seedlings.

Nature takes over:

Once canopy closure occurs, then nature takes over, and seeds dropped by birds and bats start germinating, and the gaps start to fill.

“This is an area of rainforest that really can be saved”:

The Daintree lowland rainforest has a pedigree of over a hundred million years. It’s one of the last remnants of the giant Gondwanan rainforests. It is incredibly species-rich and must be protected. Our future totally depends on these green lungs.

To learn more about the Cape Tribulation Tropical Research Station, contact Hugh at hugh@austrop.org.au, or via www.austrop.org.au