EPOW Ecology Picture of the Week -- Tree Fern Glory

Explanation: In the hot humid tropical rainforests of Mt. Lewis, Queensland, northeast Australia, grows this beautiful remnant of ancient supercontinents. Tree ferns are found in scattered tropical and subtropical regions of the southern hemisphere, telling a story of days when they were all one land.

Some species of tree ferns (of the genera Cyathea and Dicksonia) retain their dead fronds (leaves) and form a "skirt" around the trunk. More than adding to the symmetry and beauty of the plant, sometimes the skirt serves as habitat for forest birds, lizards, insects, and other life forms. As far as I can tell, this is an unstudied aspect of tree fern ecology. I have also observed this relationship with "skirts" formed by dead leaves around species of palms, yuccas, and other trees of the world. Whether the animals in turn confer some benefit to the tree fern is unknown.

Some studies suggest that "skirts" serve as a defense against lianas, climbers, vines, and other epiphytes, that might otherwise damage the tree physically or physiologically. But the relationship of the skirts to animal use apparently is unstudied.

Information:
Page, C. N. and P. J. Brownsey. 1986. Tree-fern skirts: a defence against climbers and large epiphytes. Journal of Ecology 74(3):787-796.

How I Took This Photo

I thought it might be interesting to explain how I took the above photo. I took two shots from the exact same position -- one with a flash and one without -- and then "stacked" them to bring out the brightest pixels in each photo.

Here are the two individual photos:

Left: with flash . . . . Right: without flash

Compare each of these photos with the main photo -- which is the composite, "stacked" photo -- and you will notice how the bright trunk "skirt" from the flash photo has combined with the bright backlit sky from the no-flash photo that still shows details of the underside of the flash-lit frond.

To combine these photos, I used the "brighten" option in the commercial program "Image Stacker" by Tawbaware Software.

EPOW - Ecology Picture of the Week