Biology

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Dry Wallum
The dry wallum is a harsh environment that is battered by the sun and wind every day and with a base of porous sand; water availability is very scarce and must be conserved. The abiotic factors in the dry wallum are that the area is exposed to high amounts of sunlight which causes a loss of water in the leaves through transpiration. Since the wallum is so dry and hot; bush fires play a major cycle in the dry wallum which the trees have adapted to cope with. The roots of the plant and tree species have to cope with the leeching of nutrients because of the high porosity sand in the dry wallum.

The Dry wallums topography is quite low and flat between high sand dunes covered in thick wallum vegetation. This creates a wind funnel across the island often causing windy conditions. The dry wallum is also above the water table making water scarce. The dominant plants would have to be the Banksia with its thick leathery cuticle to reduce water loss in the hot windy conditions. The Banksia grows much bigger in the dry wallum that the wet wallum due to higher amounts of nutrients in the soil and doesn’t have to use energy getting rid of excess water. The banksias are quite stunted though because of the low organic matter and nutrients in the sandy soil. High amounts of sunlight reach the ground on the wallum as there is no uniform canopy and this gives ground dwelling plants a chance to thrive spreading out over a huge surface area to gain what little water there is. Whilst in the wallum medium amounts of leaf litter were observed, this is due to the very dry environment where the bacteria’s and acids cant break down the organic matter as fast.

The plants of the wallum have adapted to the cruel abiotic factors with fire, drought, sunlight and wind all against the plants. The Banksia has tailored their leaves to be small and to have a thick leathery cuticle. The Banksia also has curved leaves with sunken stomata with hair follicles around the stomata....
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