The Build-up to the Wet Season

Skyrail Nature Diary: October 2012

As quickly as it started, the winter is over again with the first warm spells from the north having arrived. We are now going into what some people refer to as the "Build-up".

It’s getting hotter and hotter and the humidity will also rise but for now, it is the most stressful time for the forest because there hasn’t been a great deal of rain for months and the soil moisture reserves are almost exhausted. Still, the evaporation rates are climbing and plants are losing more moisture through their leaves than they can take up through their roots which is why this season does have some similarities with a temperate climates autumn where trees drop their leaves and present their bare branches like skeletons.

Our giant strangler figs in particular drop their leaves often several times a year after a dry spell and some trees turn completely red like our Terminalias (the Beach Almond and our Damsons) only to get new growth a couple of weeks later. Even the evergreen trees like the Kauri Pines are dropping lots of leaves. The reason of course is not the preparation for a freezing winter, but because plants want to prevent moisture loss through their leaves at a time when there is no water in the ground.

The ground is covered in a thick blanket of leaves just like the autumn of colder climates and this will actually act like mulch and conserve any remaining moisture in the soil. These plants are very clever to produce their own mulch and with it their own food, as these old leaves will rot as soon as the rain returns and turn into new soil and nutrients for the forest.

Some plants react completely different to the hot and dry spell. They actually prepare themselves to die and so they gather all of their last remaining energy for one enormous effort beforehand. This last effort is of course reproduction and we are still talking about flowers, more precisely orchids that are flowering or just finished flowering all over the place. They won’t die but they act like they are about to because they are suffering in this heat on their already dry habitat on the side of a tree trunk.

We do have a nice selection in the rainforest. The most prominent ones, of course are King Orchids (Thelychiton speciosus formerly Dendrobium speciosum) especially around Skyrail's Red Peak station, Pencil Orchids (Dockrillia sp.) all the way along the cableway and the Giant Boat Orchid (Cymbidium madidum) between Red Peak and Kuranda stations. The Blotched Orchid (Pomatocalpa MacPherson) is also just beginning to flower.

Apart from the plants there are of course other living things which are becoming increasingly more active due to the warmer temperatures, namely insects, reptiles and amphibians.

I took this shot of the Barron River log a couple of weeks ago and it was alive with turtles and a freshwater crocodile.

At Red Peak station we are seeing Red Bellied Black snakes again and the cicadas have returned which makes it tricky at times when talking to our guests due to their noisy calls.

Frogs are back in the dams and the first spiders, butterflies and other creatures are coming back from wherever they were on holidays for the last couple of months.

By Mike Gailer