Physical interactions within the SIHC

Relief and Climate The high relief of the Alps causes moist westerly winds to rise causing orographic rainfall = higher rainfall in the Western High Country. Most rainfall at about 1200m on the west side on the main divide 4-10,000mm – high rainfall over 3000mm per year at lower levels While in the Eastern High Country , temperature rises as the air descends to lower levels. Rainfall totals are much lower. Fohn wind bringing a strong dry NW wind. Average temp of 12 degrees in winter 20 in summer. 700mm of rain per year Southern Alps = The higher the altitude, the cooler the temperature for snow to fall instead of rain, some may survive the summer thaw. Hermitage at 765 m above sea level average temp of 7.5 degrees , peaks at below 5 degrees Up to 20m of snow per year Dry air cools 1 degree per vertical 100m Wet air cools at .6 of a degree per vertical 100m

Climate and relief The high rainfall on the western slopes gives rise to increased erosion through streams and rivers ( fluvial ) Dry rainshadow areas such as Central Otago are susceptible to wind erosion ( aeolian ) Cold temperatures at higher altitude causes glaciation and freeze thaw erosion processes to occur, which modify relief features

Relief and vegetation The high relief of much of the SIHC results in alpine vegetation (plants adapted to the colder temperatures found at higher altitudes) Because of the sparse vegetation, erosion by the wind is more common. As altitude rises this results in bands of vegetation. Vegetation will change from forests, scrubs, grasses to alpine herb fields.

Climate and vegetation Differences in temperature caused by altitude and length of growing season are key factors in determining vegetation zones. The amount of rain that falls causes vegetation to vary. The aspect ( the direction the slope faces ) will also have an effect on vegetation – a shady south facing slope will be colder and will dry out less. West of the main divide rainfall between 4000 – 10000mm favours the growth of trees to 200- 1000m above sea level. Covers all but the steepest slopes Podocarps, rimu dominant species.

Regions Western – forest composed of beech with rata and rimu at lower elevation. This is succeeded by a belt of sub alpine scrub and finally by snow grass up to the vegetation limit which is the permanent snowline ( 6,000ft ) SA – sub alpine and alpine plants – refer to SA notes Eastern – largely subalpine tussock with small patches of beech and totara forests in gullies that escaped the destruction of fire.

Vegetation and relief Because of the sparse distribution or lack of plants in parts of the high country, erosion by wind and water more common.

Soils and vegetation Thin soils results in shallow rooting vegetation such as tussock

Vegetation and soils The sparse shallow rooting vegetation such as tussocks is partly the result of thin soils. Because of the shallow roots of the plants soil erosion is much more rapid.

Climate and soils The temperate and wet climate of the forested western slopes causes slow decomposition of humus. Soils can become leached and this is podsolisation. Cold temperatures at high altitude means that soils are frozen and decomposition is slow.

Relief and soils Slope angle in particular affects the rate of run off and erosion. In steep areas the surface material is carried downslope quickly so soils can be shallow. On flatter land deposition of alluvium occurs when rivers are in flood or glaciers dump the moraine they carry. Soils that form from the rivers alluvium will be deeper and more fertile that mountain soils, but are still stony. On flatter areas of the west coast a soil has had time to develop under high rainfall it is known as a podzol.

Task 1: Diagram showing interactions Draw an annotated diagram of the SIHC and write a brief description of how vegetation, soils and climate changes at different altitudes

Task 2: Landmodifying processes Draw a side profile of the southern alps and label where these processes occur Deposition Weathering Transportation Mass movement and erosion Freeze Thaw action Also label where these landforms would occur Moraine from the Tasman Glacier Shingle and outwash plains e.g Mackenzie Basin Scree slopes - sides of Tasman Valley

Task 3: Landforms Draw up a table into your books, and describe the types of landforms that occur in each region with a brief description of why. Western High Country Southern Alps Eastern High Country

Orographic Rainfall

Soils and Vegetation

Soils and Vegetation

Tasks 4-6 Task 4. Create an annotated diagram showing the interaction of climate and relief. Task 5. Create and annotated diagram showing the interaction of soils and vegetation. Task 6. Create a diagram or table showing the spatial variation between the three SIHC study areas.