soil in the tongariro volcanic centre the spatial variation of

Soil in the Tongariro Volcanic Centre

The spatial variation of

SOILS KEY:

Azonal soils

Soils that Lack nutrients

Pumice soils and Rich red Ohakune soils

Tongariro Ash soils and fine textured loam

No soil

Spatial Pattern of Soils in the Tongariro Volcanic Centre

What are soils?

• Soils are the natural materials on the land's surface that directly support plants and bacteria, and indirectly support all animal and human life.

Soils are made up of:

• topsoil (the dark layer that you can see), which has a lot of microbes and organic matter from previous plant growth

• subsoil, which has a variety of colours and textures depending on drainage and past weathering

• underlying rocks.

How they form

• Soil builds up over time. Through gradual wearing and chemical decay, rock breaks down into smaller particles – gravels, sands, silts and clays. During this process nutrients are released, and become part of the soil.

• Many New Zealand soils are made from a build-up of fine, wind-blown sediments (loess), volcanic ash or pumice.

Layers of Soil

.

• O horizon (surface litter): Fresh or decaying organic material (e.g., leaves, twigs, moss) accumulated on the ground.

• A horizon (topsoil): Top layer of soil, which holds most of the organic matter and most of the water and nutrients needed for life. Infiltration: Seeping of water down through soil.

• E horizon: Zone through which leaching occurs. Leaching: Process by which infiltrated water picks up nutrients and carries them down to deeper soil.

• B horizon (subsoil): Zone that often contains an accumulation of minerals as well as some organic materials.

• C horizon: Zone composed of broken-down parent material, the basic type of rock from which the rest of the soil is derived.

• Bedrock: Parent material below the C horizon.

Each soil horizon has specific physical and chemical properties

Soil types in New ZealandCan you identify any patterns?

Recent Soils

Recent soils cover 6% of New Zealand. They occur where erosion and sediment build-up are low enough to allow well-developed topsoils to form. However, subsoils usually show very little development. Many of New Zealand’s most versatile soils are Recent soils. They are usually fertile and allow plant roots to penetrate deeply, unless rock or dense clay is present.

Raw Soils

Infant soils that may never grow older because of active erosion or sedimentation. Raw Soils are very young soils. They lack distinct topsoil development or are fluid at a shallow depth. They occur in environments where the development of top soils is prevented by rockiness, by active erosion, or deposition

Pumice Soils

Mostly derived from one of the greatest volcanic eruptions ever known from the crater now occupied by Lake Taupo. Pumice Soils are sandy or gravelly soils dominated by pumice, or pumice sand with a high content of natural glass. Drainage of excess water is rapid but the soils are capable of storing large amounts of water for plants. They occur in tephras ranging from 700 to 3500 years old.

Podzols Soils

Podzolised soils cover 13% of New Zealand. The name podzol comes from a Russian word for wood ash, describing the white subsoil – digging through the thin black topsoil exposes an almost white horizon (layer). Digging deeper reveals a bright ginger brown. These colours have been caused by strong acid leaching from native trees (especially conifers, beech and kauri) and high rainfall (more than 1,300 millimetres per year).

Zonal SoilsThe zonal soils clearly the impress of climate and vegetation. It consists of the brown-grey earths of the semi-arid areas where the rainfall is less than about 20 inches a year; the yellow-grey earths of sub-humid areas where the rainfall is approximately 20–40 in. a year; the high country, central and southern, and northern yellow-brown earths of the humid regions where the rainfall is well distributed and is greater than approximately 40 in. a year; and the corresponding podzolised yellow-brown earths and podzols resulting from excessive leaching beneath an acid litter of decomposing vegetation.

Azonal Soilsazonal soils, are zonal soils that have been changed as a result of variations in topography, such as erosion, moisture status, and depth to bedrock

Azonal soils are youthful

Variation of Soils in the TVC

There are 5 categories – with 4 actual soils to map.1. No soils2. Tongariro Ash soils and fine textured loam3. Yellow-brown pumice soils and rich red Ohakune zonal soils4. Thin soils that lack nutrients5. Azonal soils. Ash covering up to 2 metres of Taupo pumice

In this map, all areas of the map will be covered as all the soils are a natural feature. Locating the soils:• No soils: are located around the mountain peaks in the same location as the

bolder fields on your vegetation map – except they only are located on the peaks – do not come down the eastern side of the mountain.

• Tongariro Ash soils and fine textured loam: are located in two areas. The first in the NE quadrant where the kanuka and manuka are growing. The second is around the southern slopes of Ruapehu – where the exotic forest is located and all the beech and podocarp forest are located.

• Azonal soils: are located on the Rangipo desert between the two Tongario ash soils.

• The last two are located on what is left of the Northern and western slopes. Visually divide this area in half vertically. The most western side is the Yellow-brown pumice soils and rich red Ohakune soils. The inner western slopes are the thin soils that lack nutrients.

How does each factor affect the soil fertility / location CARVES

C = Climate

A = Altitude (height)

R = Relief (steep or flat?)

V = Vegetation

E = Eruptions

S = Stage of development

(this is the heading – you don’t have to write anything except the stage number)

Tongariro Ash Soils & Fine Textured Loam

Climate: Eastern side: Not that much rainfall – 1048mm per year due to rainshadow effect of Mt T and Mt N. This means there is very little leaching of the nutrients from the soil.

South Western & Southern sides: While there are high levels of rainfall due the orographic rainfall caused by Mt R; over a long period of time this has caused the area to have a very lush vegetation which then significantly contributes to the nutrient cycle keeping the soils fertile. Here the vegetation keeps the soils from being leached.

This soil is important and is widespread in TVC


Altitude: • 1000-1300m high.


Relief: • Rolling foothills – soils are able to

remain on this type of terrain as it is not too steep.


Vegetation: Beech, Podocarp and Scrubland. Good vegetation helps add to the nutrient cycle. The more vegetation, the more decaying of leaves the more nutrients are then added back into the soil. Therefore these soils are very fertile.


Eruptions (in history): • Eastern side: Mt T & Mt N last erupted in 1974

which means that the soils have had to re-develop their fertility in the last 40 years.

• South Western & Southern sides: Up until the 1990s, Mt R had been relatively dormant due to the hot spot being in the north. This meant that soils have had a long time to redevelop their fertility. Today, the prevailing Westerly winds help to maintain this fertility by blowing the ash to the East meaning that the soils are less affected.


Stage: • Later stage of development – nutrients are

present• It takes approximately 50 years for soils to

become fully fertile after eruptions. • These soils have not been greatly affected

by eruptions for over 40 years. • Fine texture, dark brown, mixed with ash

from the Tongariro eruption. Quite fertile.

Yellow-Brown Pumice & Rich Red Ohakune Zonal Soils

Climate: • 2800mm of rainfall due to orographic

rainfall which has leached the soils in the past due to the slow vegetation succession


Altitude: Low


Relief: Rolling relief is not steep and so does not inhibit the soil (and vegetation) to develop


Vegetation: • Mainly tussock and scrubland. On

these lower foothills there is more scrubland than tussock leading to more soil development as the vegetation adds to the nutrient cycle and is helping to reduce the leaching of the soils.


Eruptions:


Stage of Development:

Thin soils that lack nutrients Sheenal

C = high amounts of leeching due to high levels of rainfall from the orographic effect. This removes nutrients from the soil

A = 1200-1400m

R = Steep slopes of the mountain make it harder for the soil development process to occur

V = Small amounts of vegetation, not enough soil to grow all types of vegetation

E = Relatively close proximity to vents means that the soil is vulnerable to damage from eruptions

S = Middle stage of development with some nutrients

Azonal Soils Monleigh

C = Rain shadow effect occurs as a result of prevailing SW wind, strong winds. SW wind carries ash over this area

A = 1000-2000m

R = Relief is relatively flat; on the ring plain of Ruapehu

V = Vegetation is mainly tussock and scrub

E = Eruptions have prevented the regrowth of forest on the slopes due to SW winds

S = Early stage of development because of Aeolian erosion and sedimentation

Soil Categories

Zonal Soils: Determined by the climate and vegetation. These are older soils.

Azonal Soils: Determined by other factors like alluvial (to do with rivers), moraine (to do with glaciers), aeolian (to do with wind) and tephra (to do with volcanoes). These are young soils.

Yellow-brown pumice soils and rich red Ohakune zonal soils

• YB – silt to coarse gravel , good drainage because the pumice is porous, a bit of clay.

• RO zonal soils – older soils created from different tephra from Mt T and N’s eruptions.

Azonal soils

• Young soils created from the deposition (the depositing) of tephra from Mt Ruapehu ash covering 2m of Taupo Pumice soils.

Tongariro Ash Soils and Fine Textured Loam

• Fine texture, dark brown, mixed with ash from the Tongariro eruption. Quite fertile.

Thin soils, lack nutrients

• Very coarse gravels, low levels of actual soil. Leaching occurs very easily here.

The final product: A Study Summary of Soil in the TVC

• Use the colour print out(the soil map I gave you last Thusday) and the notes from this PowerPoint to make a layout that looks like the following slide…

• (either hand write it- or type and print it)

• NOTE: your layout will have more information than this one example box so don’t simply copy it out!

SOILS KEY:

Azonal soils Soils that Lack nutrients Pumice soils and Rich red Ohakune soils Tongariro Ash soils and fine textured loam No soil

Northern Tongariro Ash Soils and Fine Textured Loam• Climate• Altitude• Relief• Vegetation• Eruptions• Stage of soil Development.

Spatial Pattern of Soils in the Tongariro Volcanic Centre

• Azonal SoilsClimate• Altitude• Relief• Vegetation• Eruptions• Stage of soil Development.

Pumice Soils & Rich Red Ohakune Soils• Climate• Altitude• Relief• Vegetation• Eruptions• Stage of soil Development.

Southern Tongariro Ash Soils and Fine Textured Loam• Climate• Altitude• Relief• Vegetation• Eruptions• Stage of soil Development.

Soils that lack nutrients• Stage of soil devt: Middle stage as

there are only some nutrients• Climate: 2838mm rainfall means lots of

leaching• Altitude:__________• Eruptions: The Taupo Caldera erupted

approximately 2000yrs ago wiping out the podocarp forest that existed here. Subsequent eruptions from Tongario and Ngauruhoe have continued to slow soil devt by depositing ash and making the soil acid. Until 2012, the last eruption was over 50yrs ago, allowing acidity to reduce and fertility to increase.

• Vegetation: Tussock and scubland like flax is growing slowly beginning to hold the soil together and adding nutrients to the soil through decomposition processes.

• Relief: Relatively flat with a few small rolling valleys which means that soil is generally able to stay in one location, as long as it is protected by vegetation.

It’s not just the soil that ash lands on!

soil in the tongariro volcanic centre the spatial variation of

Documents

recent soils recent

raw soils infant soils

soils key

azonal soils

versatile soils

gravelly soils

podzols soils podzolised

young soils