Soil Science

Biota

High country near Point Lookout, New South Wales

Plants and soil organisms both influence and are influenced by the soil in which they grow.

There is often a correlation between the distribution of soils over a landscape and the distribution of vegetation, because both have been affected by the same parent material, climate and topographic factors.

In the picture above, the flat land in the foreground is naturally treeless and is associated with a change in soil type.

The soils are outlined below.

Valley flat without trees

Great Soil Group: Humic gle
Australian soil classification: Redoxic Hydrosol

Biota
Great Soil Group: Humic gley
Australian soil classification: Redoxic Hydrosol

The presence of permanent waterlogging in the lower part of this soil profile has produced gleying (gray and rusty-colored mottles). The anaerobic conditions prevent deep root penetration and the establishment of trees. This soil can also be expected to have a high concentration of organic matter.

Hillslope with trees

Great soil group: Chocolate Soil
Australian soil classification: Red Dermosol

Biota.
Great soil group: Chocolate Soil
Australian soil classification: Red Dermosol

The chocolate soil is relatively well-drained (no mottling, gleying) and is fertile. A boulder of basalt parent material can be seen in the picture.

There are no soil restrictions on tree root growth. Soil organic matter concentrations will be less than in the humic gley.

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