We humans like things to be nice and neat. We like to categorize things like ecosystems. Fortunately nature doesn’t work like that. Subsequently, clear boundaries between adjoining ecosystems don’t always exist.
The obscure boundary that contains elements of each ecosystem is called an ecotone. It is basically a zone of transition from one ecosystem to another.
As Sheoak Ridge Nature Reserve contains six recognized remnant ecosystems there are many localities where ecotones occur. The two most obvious of these are the boundary between the Rainforest and the blue gum woodland, and the Rainforest and the bloodwood woodland. In both of these localities the cessation of burning has allowed rainforest plants to become established in areas where they were previously killed-off by fire. Subsequently species that have no adaptations to deal with fire are now growing amongst ones that do. For example celerywood (Polyscias elegans) growing amongst narrow-leaved ironbark (Eucalyptus crebra)
An interesting feature of ecotones is that they often contain a greater species diversity than either single ecosystem. They may even contain species that are only present within the ecotone. For this reason the conservation of ecotones is just as important as the conservation of ecosystems.
In my opinion the rainforest ecotone at Sheoak Ridge represents a active transition from one type of ecosystem to another. For that reason I do like to refer to this area as a transitional forest, and believe that this is a separate ecosystem, even if it is in flux.
Hopefully this concept will be investigated in October 2014 when the next round of Targeted Research Projects (TRP’s) are carried out by students from Stanford University.
In 2011 a related TRP was undertaken by Graham Provost.