Pallida

Formerly known as ‘The Winery’, Pallida is a 33-hectare property that has been largely cleared. Historically, it has been subject to grazing and slashing.

Work on this property has focussed on control of pasture grass species including kikuyu, setaria, and dactylus, monitoring natural regeneration and growth measurements on regenerating native plants.

Monitoring

For the purpose of monitoring, the property has been divided into a 150-metre grid, further divided into 16.67 m x 16.67 m cells.

Natural regeneration

Historical aerial photography shows that by 1930 the property was almost totally cleared. By 1989, there had been significant regeneration on the upper slopes, but in 1992 it was again cleared.

It is reported that the clearing in 1992 was followed by heavy rain and major erosion occurred such that the pool at the foot of Twin Falls in Springbrook National Park was filled with mud from the property.

Since the property was acquired by the Queensland Government in 2007, there has been significant regeneration of native species. The main species are Lomatia arborescens, Acacia melanoxylon, A. orites, Persoonia media, Callicoma serratifolia. A total of 52 species has been recorded including three rare species.

Several ecosystem conditions occur across the 33-hectare property. A major proportion is considered to be a herb-dominated stable state where kikuyu (Pennisetum clandestinum) covers the ground. The dense mat excludes light, thus providing its own positive feed-back loop. The kikuyu-dominated area occurs mainly on the lower slopes and the flatter ground at the northern end of the property. Also in the lower part of the property is another herb-dominated ecosystem likely to be a stable state. The dominant species is Dactylus glomerata, apparently planted for fodder.

On the upper slopes, there is a distinct difference between the westerly and northerly aspects. The westerly aspect is dominated by whiskey grass (Andropogon virginicus) whereas the northerly aspect is dominated by kikuyu. Rainforest regeneration is more advanced in the whiskey grass area.

Most of the natural regeneration that is occurring is on the upper slopes. Where regeneration is occurring on lower areas, the location of individual plants has been marked with pink plant markers. The main species are Acacia melanoxylon, A. orites, Lomatia arborescens and Persoonia media.

Growth measurements

Three cells have been selected for growth measurements, two on the western side of the property adjoining advanced regeneration and one towards the northern, lower end of the property. Measurements are made at the beginning of each season, recording height, breadth, general health (including mortality), leaf area index and herbivory. More than 500 plants are being recorded.

Threats and barriers to restoration

Exotic grasses
The major barriers to natural regeneration are the grasses kikuyu (Pennisetum clandestinum), setaria, Setaria sphacelata var. sericea, and dactylus (Dactylus glomerata).

Parts of the upper slopes of the property are infested with setaria. This grass grows to 2 m high and in dense clumps. It essentially smothers regeneration.

Mowing, slashing and brushcutting have been carried out on areas dominated by kikuyu, setaria and dactylus. The objective in cutting these grasses back to ground level is in general to reduce biomass and therefore competition with native seedlings. However, it is recognised that this may be effective only where seed dispersal is adequate and where the cutting back has reduced the effectiveness of the self-supporting positive feed-back loop of kikuyu.

Fireweed
Fireweed, Senecio madagascariensis, appears across the property annually. Whereas it is not considered to be a significant threat or barrier to regeneration, it is a Class 2 declared weed under the Land Protection (Pest and Stock Route Management) Act 2002, and is required to be controlled by landholders.

Teams of volunteers have repeatedly removed fireweed by hand-pulling. Because of propagule pressure from its wind-dispersed seeds, it will not be eradicated until a canopy provides shading.