EXTENDING YOUR IDEAS
The wallum is a stunted vegetation found in sandy, low nutrient soils. The larger mammals such as wallabies and kangaroos feed on grasses which are sparse in these areas and larger possums, koalas etc., are adapted to tree species which cannot grow in these conditions. Since these heathland plants flower prolifically during much of the year, organisms adapted to nectar, flower and fruit eating (e.g. honey-eating birds, small mammals and insects) are attracted to the wallum. These in turn attract organisms which feed upon them, such as snakes, lizards and insectivorous birds.
2. The soil does not retain enough water for rainforest growth.
3. a. Sirex – pine tree habitat
Sirex larvae – Amystereum predation
Amystereum – pine tree parasitism
Birds – Sirex adults predation
Megarrhysa larvae – Sirex larvae predation
Ibalia larvae – Sirex larvae predation
Deladenus – Sirex, Megarrhysa, Ibalia parasitism
Deladenus – Amystereum predation
b. Megarrhysa successfully destroyed most of the Sirex larvae and thus further generations of eggs were not laid in the trees along with the Amystereum filaments.
c. Several hypotheses possible, e.g.:
The original infestation of Sirex was so large that not all of them have been destroyed by the introduced species.
There have been migrations of Sirex from adjoining areas, as the numbers were reduced by the control species.
4. Answer variable depending on choice of community. Information for wallum given in text,
e.g.: since wallum is found in Queensland, insolation is high leading to tropical–warm temperate climate with high summer rainfalls and drier winters. Soil is derived from sandstone and sediments – low nutrient and water retention. Between the soil and the climate the type of flora is limited to heaths and shrubby trees and this limits the type of fauna. (Give examples of both and their adaptations to these conditions). Plant matter and animal droppings add humus to the soil which is either decomposed and the matter recycled, or helps in the development of hard clay pans which limit movement of water downwards. This results in the formation of swamp areas in which only certain types of plants are adapted e.g. paperbarks and rushes.
5. Answers to include information from three of the following four options:
Macropus robustus robustus
Temperature range between 27–32°C January and -1–16°C July; mean annual rainfall greater than 800 mm; rainforest, temperate forest or savannah woodland.
Macropus robustus woodwardi
Temperature range greater than 30°C January and 10°C July; annual rainfall 500–800 mm; desert, arid scrub, grassland and savannah woodland.
Macropus robustus erubescens
Temperature range greater than 32°C January and -1°C July; annual rainfall below 500 mm; desert, arid scrub, grassland, mallee scrub.
Temperature range between 27–38°C January and greater than 10°C July; mean annual rainfall greater than 800 mm; savannah woodland, monsoon forest.
6. The fly larva has a very high rate of evaporation, from 50 to 25°C, thus would be most likely to be found in cool, shaded and enclosed places with a high moisture content (and thus humidity), e.g. decomposing matter that is protected from the direct sun. Up to 40oC the evaporation rate of both the crustacean and the beetle is relatively low, although that of the crustacean is higher. It is probably found in leaf litter such as that found in a rainforest. The beetle would probably be found in more open areas of forest or woodland since it has the lowest evaporation rate at higher temperatures.
7. Either argument is valid but must be backed up with suitable data.
8. a. Black kite group – predators of insects and small birds fleeing from the fire.
Pied butcherbird group – scavengers of animals which have been killed by the fire as well as predators of those escaping fire.
Whistling kite group – predators of organisms fleeing fire, scavengers of those killed in the fire and predators of other scavengers.
Owl group – scavengers of animals killed in the fire.
Straw-necked ibis – insect eater – those fleeing the fire or scavenging on carcasses.
Red-tailed black cockatoo – seeds and nuts released during the fire.
Partridge pigeon – seeds released during the fire, suckers and young grasses.
Little corella group – suckers.
b. The fire represents a disclimax community. Although many plant species will have organs such as dormant bud, lignotubers, and specialised bark so that they do not die during the fire, some will not be able to survive. Animals which cannot move quickly ahead of the fire will be killed. Thus for a period after the fire, the plant community will be all but nonexistent and the only animals will be scavengers and those that prey on the scavengers. As the plants begin to regenerate, those species of animals that utilise young plant growth (and their predators) will return to the area, the biodiversity becoming greater as the forest returns to its natural state.
9. This is a variable answer depending on the animal selected.
Concept map (part b) should include tolerance ranges of abiotic factors and detailed food web showing relationships of biotic factors.
Prediction (part c) should show evidence of good analysis of data and should demonstrate logical sequencing of ideas in developing the prediction.