How landcape, soils, water and vegetation connect

Landscapes, Soils & Surface Environments - Workshop 1b

Raphael Viscarra Rossel, Lewis Walden

2026-02-17

Recap

  • You sketched landscapes you know
  • You noticed patterns in:
    • Soils
    • Water
    • Vegetation
  • Today: build a simple framework to explain those patterns

Sustainable development challenges

  • Land degradation

  • Food insecurity

  • Water scarcity

  • Biodiversity loss

  • Climate change

All of these are linked to landscape, soil, water and vegetation.

The SDGs and the environment

SDGs depend on healthy landscapes, soils, water, vegetation:

  • SDG 2: Zero Hunger (food production…)
  • SDG 6: Clean Water and Sanitation (quality, sedimentation…)
  • SDG 13: Climate Action (carbon storage, emissions…)
  • SDG 15: Life on Land (biodiversity, habitat…)

Understanding connections between landscape, soil, water and vegetation is crucial.

The big picture framework

The guiding principle linking all the components of this unit is:

Important

Environment → Landscape → Soil → Water → Vegetation → Feedbacks

  • We’ll zoom briefly into each part

  • Then zoom in on a hillslope as our “lab”

Environment

What is the environment?

  • The physical, chemical and biological context

  • Sets the conditions for everything else that follows

  • Large-scale controls:

    • Climate
    • Geology
    • Biological activity

Environment: examples

Think of Australia (or WA):

  • Climate zones (arid interior, temperate south-west, monsoonal north)
  • Different parent materials (sandstones, basalts, granites)
  • Different biota (eucalypt woodlands, shrublands, grasslands)

These create different possibilities for landscapes and soils.

Landscape components - the spatial template

Landscape components:

  • Landforms: the shape of the terrain (summits, midslopes, footslopes, valleys, floodplains)
  • Water: surface and subsurface water features (streams, wetlands, groundwater)
  • Soil: variable soil types, depth, texture (physical, chemical and biological properties)
  • Vegetation: composition and structure of plant communities (types, cover, height)

Note

They vary systematically with landform, soil, water and energy gradients, not randomly.

Landscape on a map

Look at this image and see if you can identify:

  • Where are the ridges and valleys?
  • Where are the streams or drainage lines?
  • Where is land cleared or vegetated?

The landscape is the spatial template that organises soil, water, and vegetation.

Processes that shape landscapes

Two broad types of processes:

  • ⓵ Internal (from within the Earth)
    • Plate tectonics
    • Volcanism
  • ⓶ External (at or near the surface)
    • Weathering
    • Erosion
    • Deposition

They operate over very different timescales.

From processes to forms

  • Uplift → steeper slopes → more potential for erosion
  • Erosion → removes material from slopes
  • Deposition → builds plains, floodplains, deltas

Over time, these processes create the landforms we see.

Ridges, summits, midslopes, footslopes, valleys, floodplains, etc.

Soil: product and archive of landscape processes

Soil is:

  • A product of climate + organisms + landform + parent material + time
  • An archive of processes that have shaped the landscape over time
  • A key regulator that influences water, nutrient and energy flows
  • An integrator that links landform, water, vegetation and organisms
  • Soil stores water and nutrients, hosts organisms, supports vegetation

Tip

Diverse soils ➡ diverse landscapes

Soil in the landscape

  • Different colours represent different soil types with different properties

  • Patterns relate to:

    • Parent material
    • Topography
    • Climate and
    • Vegetation history

Water: the connector

Water connects the atmosphere, soil, vegetation and streams.

  • Strongly controlled by:

    • Topography (slope, curvature)
    • Soil properties (porosity, structure)
    • Vegetation (roots, interception)

  • Drives weathering, soil formation, vegetation growth

  • Influences erosion, sediment transport

Water in the cycle

  • Precipitation reaches the surface
  • Some infiltrates into soil, some runs off
  • Evaporation and transpiration return water to the atmosphere

Note

Water movement is controlled by landscape form and soil properties.

Vegetation: expression and agent

  • An expression of climate, soil and water conditions

  • An agent that modifies the landscape

Vegetation: responds to soil, water and topography. Controls:

  • Erosion and sediment transport
  • Soil formation and organic matter
  • Water infiltration and evapotranspiration

Landsat 8 image over Cambridge Gulf and the Ord River estuary in Western Australia. Visible light bands highlight the different types of water. Shortwave and near infrared bands highlight the mangroves and vegetation on the land.

Vegetation patterns

  • Different vegetation types occupy different parts of the landscape

  • Patterns reflect underlying:

    • Soils
    • Water availability
    • Disturbance history (e.g. fire, clearing)

Interconnected systems

Landscapes linked through continuous feedbacks.

  • Landscape controls: Water flow paths; Erosion and deposition

  • Soil controls: Water storage; Nutrient availability

  • Water drives: Weathering; Soil formation; Vegetation growth

  • Vegetation: Modifies soil structure; Alters water movement; Influences landscape stability

South America’s Pantanal, the world’s largest tropical wetland. The landscape, soils, water and vegetation are all interconnected in this dynamic system.

Not independent components, interconnected systems!

Spatial scales

Landscapes organised and function at multiple scales, each with characteristic processes.

  • Global (~10,000–100,000 km): climate zones, biomes, plate tectonics
  • Continent (~1000–10,000 km): climate zones, major biomes
  • Region (~100–1000 km): climate, geology, major landforms
  • Catchment (~10–100 km): drainage networks, erosion zones, vegetation
  • Hillslope (~0.1–1 km): soil–water–vegetation gradients
  • Site (~0.001–10 m): soil structure, roots, organisms

Patterns at large scales emerge from processes at smaller scales

Why focus on a hillslope?

A hillslope is a useful “lab” because:

  • It contains:

    • Ridge → midslope → footslope → valley

  • Across this short distance we see:

    • Changes in soil depth and texture
    • Changes in water movement
    • Changes in vegetation

We’ll now sketch a simple hillslope.

Activity: sketch a hillslope

Instructions (15 min):

  1. Draw a side view from hilltop to valley bottom
  • Label where you expect:
    • Different soils (sandy/clayey; shallow/deep; drier/wetter)
    • Water behaviour (runoff vs infiltration; fast vs slow)
    • Different vegetation (trees, shrubs, grasses; cleared vs native)

Activity: explain and share

  1. Write (2–3 min)

One or two sentences explaining one the patterns,

e.g. “Soil is deeper at the footslope because …”; “Trees are in the valley because …”

  1. Share in pairs (5 min)

Compare sketches, find:

  • One similarity
  • One difference

Be ready to share one idea.

Debrief: what did you see?

Let’s hear a few examples:

  • One soil pattern and its explanation
  • One water pattern and its explanation
  • One vegetation pattern and its explanation

How do these relate to our `chain’:

Environment → Landscape → Soil → Water → Vegetation → Feedbacks

Example hillslope and catena

This sequence of soils along the hillslope is called a catena

Side view of a hillslope:

At each position:

  • Soils differ (depth, texture, drainage)
  • Vegetation and land use often differ

What is a catena?

A sequence of related soils down a single hillslope

  • Same climate and parent material
  • Systematically different due to hillslope position because of:
    • Water movement
    • Redistribution of materials (clay, organic matter, salts)
  • Links topography ➡ water flow ➡ soil properties ➡ vegetation patterns

Key takeaways

  1. Environment sets broad constraints (climate, geology, biota).
  2. Landscapes organise space into landforms that shape where soils, water, and vegetation occur.
  3. Soil the integrator store, transform water and nutrients, supports vegetation, records long-term processes…
  4. Water linkings atmosphere, soil, vegetation, and streams.
  5. Vegetation both responds to and modifies soils, water, and landscape stability.
  6. Scale matters: hillslopes are a powerful place to see soil–water–vegetation patterns emerge.

These ideas underpin much of what we’ll do in the next weeks.

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