Gondwana Link

The Tingle Forest

In the cool, wet forests between Walpole and Denmark on Western Australia’s south coast, three species of Eucalypt seek refuge from the drying conditions that have seen most of the ancient rainforest relicts lost. The tingle trees (Rate's Tingle Eucalyptus brevistylis, Red tingle Eucalyptus jacksonii and Yellow tingle Eucalyptus guilfoylei) can be up to 400 years old and are the dominant species in the stands in which they occur. The common name, “tingle”, is believed to be derived from a Noongar word for these trees.

The Red Tingle is the tallest of the three trees, growing up to 60 or more meters and its size is made more impressive by the buttressed trunk necessary to support the shallow rooted trees.

Rate's Tingle and Red Tingle are closely related, belonging to the subgenus (Eucalyptus) and are the most restricted in distribution. Yellow Tingle is taxonomically quite unrelated (it’s in its own subgenus, Cruciformes) and has the largest distribution of the three. There is only one main area where all three tingle species co-occur, and all three of the Tingles also occur with Jarrah (E. marginata), Karri (E. diversicolor) and Marri (Corymbia calophylla).

Within the narrow geographical range in which they occur, the tingles are further restricted by soil types and by site moisture. The three species are closely associated with the higher hills in the area and with the granite rocks. These higher areas tend to receive quite a bit of drizzle when other lower areas may receive none, and water is shed at that base of the granite rocks to create a niche environment that is far less seasonally pronounced than the rest of the southwest. These safe havens around granite outcrops may be extremely important refuges for many species and communities under continuing climate change and are the subject of a Curtin University research project.

The rich mosaic of habitat types associated with the cool, wet forests means that there are many other short range or localised endemic species to be found here. Under the closed canopy created by the forest trees, life on the ground is also favoured by the cool, moist conditions through the year. Here are found the Gondwanan spiders, including the Trapdoor Moggridgea tingle as well as species of fungi such as Descolea maculata and Rozites symea, which are mycorrhizal Gondwanan relicts confined to moist forest localities (Bougher and Malajczuk 1985, quoted in Wardell-Johnson and Coates 1996).

While not associated with the Tingle trees, there’s another very short range endemic tree species that grows nearby: Corymbia ficifolia, the Red-flowering Gum. This grows only in low-lying areas, typically in ecotones between the swampy plains and the granite rises in a couple of small areas just west of Walpole – with a few plants also found in one outlier clinging to a hillside on the coast east of Albany. It’s become far more widespread though because of its bright red, orange or pink flowers that make it a spectacular addition to any garden planting; in fact it’s one of the most popular nursery plants. It’s related to the Marri, C calophylla, and can forms hybrids with it.

Peat swamps occur in some low lying areas and are another habitat in which the environmental conditions of past climatic ages has been preserved, albeit in small, isolated and limited locations. These swamps harbour species like the Sunset Frog (Spicospina flammocaerulea), only discovered in 1994 and perhaps only occurring in less than 30 individual locations covering as little as 135 ha, with a total population that may be no more than 5000 individuals. In such precarious habitats, the impacts of climate change could be catastrophic, with fire a constant threat.

REFERENCES:

Wardell-Johnson, G. and Coates, D. (1996). Links to the past: local endemism in four species of forest eucalypts in southwestern Australia. Pages 137-54 in “Gondwanan Heritage: Past, Present and Future of the Western Australian Biota”, edited by S.D. Hopper et al. Surrey Beatty and Sons, Chipping Norton, 1996.

Bougher NL & Malajczuk N (1985) A new species of Descolea (Agaricales) from Western Australia, and aspects of its ectomychorrhizal status. Australian Journal of Botany 33:619-27.