Basalt is a type of volcanic rock which is very porous and highly erodable while also very fertile and conducive of good plant growth. As such, in combination with a high rainfall, at Springbrook it supports lush rainforest of various types. Basalt forms various geological layers of Springbrook and is identified by rich red/orange soils and dense rainforest.
Dry sclerophyll forests at Springbrook are dominated in the canopy by numerous types of Eucalyptus, Corymbia and Angophora species with occasional Lophostemon. They are more open in structure and less diverse than wet sclerophyll forest and generally occur on poorer soils. The understorey is usually dominated by grasses and sparse small shrubs. Dry sclerophyll forest has a higher fire frequency and more fire-tolerant and fire-dependant species than wet sclerophyll.
At Springbrook, Dry sclerophyll forest is found on the lower slopes and scarps mostly on the north and north-western flanks of Springbrook.
Montane heath is found on the higher rocky pavements and exposed cliff tops at Springbrook, where soils are usually shallow and free-draining. The vegetation is usually small and stunted, made up of various heathland shrubs and herbs, and sometimes including small trees and grass trees. Coral fungi and ground orchids are common in some areas.
Rainforest at Springbrook occurs primarily on the richer basalt soils and varies in structure and canopy height according to elevation. Subtropical rainforest can be found in lower parts of Springbrook, while warm and cool subtropical rainforest can be found at higher elevations. The highest peaks of Springbrook are very similar to classic cloud forests and many species depend on the water and shelter these regular clouds provide. Rainforest is distinguished by a dense canopy and a wide range of plant and animal types. Plant species include a wide range of canopy and undrstorey trees, large buttressed trees and giant strangler figs, palms, lush tree ferns, ground ferns and epiphytic ferns, epiphytic orchids and large vines (or lianas).
Rhyolite is a type of volcanic rock which is very tough but eventually breaks down to form poorer soils which support mostly sclerophyll forests, dominated in the canopy by Eucalyptus, Corymbia, Lophostemon and Syncarpia species. Rhyolite forms various geological layers of Springbrook and is easily seen exposed as the harder vertical cliffs sandwiched between layers of basalt.
Sclerophyll means 'hard-leaved'. There are two 'types' of sclerophyll forest at Springbrook, wet sclerophyll and dry sclerophyll. While rainfall plays some role in the differences, the main influence is changes in the underlying geology and soil type. See wet sclerophyll and dry sclerophyll in the glossary.
A Strangler Fig is any one of several local species of Fig (Ficus) which have the similar habit of starting life on the upper branches of another tree, where they are deposited as fresh seed by birds or bats. If conditions are right for germination, thus begins a slow process where eventually the roots reach the forest floor and the Fig rapidly increases in size. It soon grows branches and (typically large) leaves above the host tree, blocking out the sunlight. It's host also struggles to compete for water and nutrients down at ground level, and is restricted from any lateral growth by the ever-enclosing truck of the Fig. It eventually succumbs to the Strangler Fig, and after a while rots away, leaving a Strangler 'skeleton'. Strangler Figs are a common site in subtropical rainforests, seen in various stages of growth. They give a rare glimpse into the different time scales that these ancient forests are accustomed to!
Wet sclerophyll forests at Springbrook are dominated in the canopy by numerous types of Eucalyptus, Corymbia, Lophostemon and to a lesser degree Angophora and Syncarpia species. The mid-storey contains some Wattles but mostly young rainforest trees. The understory is dense with smaller rainforest trees and shrubs and many ferns and tree-ferns, palms, cycads, herbs and vines. Often with high animal and plant species diversity, these forests vary according to elevation, aspect and fire history.
Some of the best examples of old-growth wet sclerophyll forests that remain in Queensland can be seen along the tracks to the west of Appletree Park.