Opening up the rainforest canopy to science (Biodiversity Science Article)
12 June 2012
Photo: Epiphytic orchid growing on top of a layer of moss and lichen (taken by Sven Batke, DRC 2010)
A recent paper by Adrian Seymour and Sven Batke has been published in the Operation Wallacea's e- journal Biodiversity Science: Developments in biodiversity and conservation management.
Modern rope access techniques combined with the latest technology are opening up the rainforest canopy and allowing ecologists to survey a much neglected area.
The rainforest canopy is only 30 to 50 metres up, yet because it is practically inaccessible and obscured by lower layers of foliage, it never receives anything close to the scientific scrutiny that it deserves. The rainforest canopy is where the trees gather light, photosynthesize and exchange gases. This zone harbours entire communities of animals and plants that live nowhere else.
For example, functionally important plant groups such as epiphytes, which provide important habitats for many vertebrates and invertebrates, reach their highest abundance and diversity in the mid and upper canopy zones more than 15m from the ground, are frequently under-represented in rainforest botany surveys.
Epiphytes – plants that grow on other plants (usually trees) – are an important component of botanical and structural diversity in forests, and in some instances exceed the terrestrial plant diversity. Those in African rainforests have been especially under-represented in the scientific literature.
To address this, an expedition set out to conduct a preliminary survey on epiphytes on 40 mature trees located within two 1km2 woodland plots.
The canopies were reached using rope access techniques. These techniques consist of first shooting a throw line over a suitable high anchor branch with a catapult, then hauling over the climbing ropes and securing them, and then using climbing gear to ascend the ropes and move around in the crown of the tree.
There are various styles of climbing techniques and equipment, but in all cases the kit required is fairly light and can be easily carried to any tree that one wants to sample.
Over a period of 30 days two climbers managed to map epiphytes and collect samples from over 900 branches in the 40 sample trees. The resulting data gave a unique picture of the patterns of distribution and abundance of all epiphytes covering the sample trees.
For example, epiphytes showed strong responses to the aspect of different branches. Branches that received more solar exposure during midday had fewer epiphyte species than branches elsewhere. A similar trend was observed with their height in the tree, where many epiphytes avoided sites of excessive light exposure (eg the outer canopy) and were more abundant in medium exposed sites (ie the mid-canopy).
The study was published in the Operation Wallacea's e- journal Biodiversity Science website, read the full article at this web link