Carbon Dynamics and Assessment Overview

Landscape soils and surface environments - Week 4 Workshop 2b

Raphael Viscarra Rossel, Lewis Walden

2026-03-11

Recap

We have just:

  • Looked at contrasting SPAC systems
  • Applied the water balance and seen how water is partitioned in different ecosystems
  • Examined hydrological feedbacks (e.g. clearing ➜ recharge ➜ salinity)

Now the focus is on:

  • Carbon cycles and disturbance dynamics in the SPAC
  • Using land management scenarios to trace C inputs, outputs, and feedbacks
  • Finishing with an overview of the assessment task

From patterns to dynamics: Why scenarios?

Spatial patterns tell us:

  • Where soil C is high or low
  • How C relates to vegetation, climate, soils

But they are snapshots:

  • Show outcomes, not trajectories
  • Hide timescales and rates
  • Don’t show transitions or tipping points

Scenarios let us:

  • Trace C dynamics through time
  • See feedbacks emerge and break down
  • Explore alternative trajectories under disturbance

Activity (40 min): The Australian carbon balance game

You inherit an Australian landscape that is degraded

You now have 50 years to manage it back to ‘health’.

Your goal: recover as much carbon as possible

— You win by achieving at least 70% carbon recovery by the end of 50 years.


Click this link: The carbon balance game

or copy this: https://ravr19.github.io/lsse_teaching/carbon_balance_simple_app.html


Follow the instructions in the app and answer the questions provided.

Key takeaways (1)

Key ideas from today:

  1. NPP and allocation set potential carbon inputs to soil.

  2. Soil C stocks reflect inputs vs outputs integrated over long timescales.

  3. Disturbances (clearing, fire, succession) change both:

    • Water balance (SPAC, ET, recharge)
    • Carbon balance (NPP, R\(_h\), erosion, fire)

Key takeaways (2)

  1. Feedbacks can:
    • Accelerate degradation (low C ➜ poor soil ➜ low NPP)
    • Promote recovery (improving soil ➜ more vegetation ➜ more C)
  2. Timescales matter:
    • Hydrology often responds faster than soil C stocks.

Key takeaways (3)

  1. Patterns reveal processes: Spatial contrasts (e.g. Banksia vs Jarrah, degraded vs intact) show how water and carbon dynamics differ.

  2. Scenarios reveal dynamics: Tracing disturbances (clearing, fire, succession) highlights timescales, feedbacks, and alternative trajectories.

  3. The soil–plant–atmosphere continuum is central: Water potential gradients and plant hydraulics underpin both water and carbon fluxes.

Next: Information on the assessment.

Assessment overview

Unit assessment:

  • Report & Presentation (40% of grade)
  • Written report (2500 words) + 7 min presentation
  • Scheduled towards Weeks 12–14

Today: High-level overview of:

  • Structure and purpose
  • Skills you are building towards it
  • Timeline and milestones

Assessment structure

1. Landscape Management Brief (Week 14)

  • 2500 words (~6–8 pages)
  • Focus: Swan Coastal Plain–Darling Scarp landscape
  • Integrate concepts from ULO1 and ULO2
  • Evidence-based analysis for a professional audience

2. Oral Presentation (Week 12)

  • 7 min presentation
  • 3 min Q&A
  • Clear findings and recommendations

Note

Audience: researchers, government agencies, DBCA, DPIRD, NRM groups

Nature of the scenarios

You will work with a SCP–Darling Scarp landscape scenario:

Possible scenarios include:

  • Land-use change and effects on soil, water, and carbon
  • Restoration of degraded sites (e.g. secondary succession)
  • Hydrological and soil C implications of management options
  • Conservation planning in a fire-prone Banksia–Jarrah landscape

Your task:

  • Diagnose the current state using SOC/pH/Clay/AWC
  • Analyse likely trajectories under alternative actions
  • Advise a diverse landscape management audience

Skills you are building (Weeks 1–6)

Weeks 1–3 (ULO1):

  • Spatial patterns in the SCP–Scarp area
  • Soil–landscape formation and variability

Weeks 4–6 (ULO2):

  • Dynamic relationships in the SPAC
  • Carbon and nutrient cycling
  • System feedbacks and trajectories

These skills allow you to:

  • Interpret real landscape management problems
  • Anticipate consequences of interventions
  • Communicate system behaviour to professional audiences

Timeline and milestones

Key dates: Subject to confirmation in the detailed brief

Week Milestone
8–9 Scenario released
10 Progress check-in
12 Presentations
14 Brief due

You will receive:

  • A detailed assessment brief
  • A marking rubric
  • Guidance on professional Brief expectations

What makes a strong Landscape Management Brief? (1)

Key elements:

  1. System understanding
    • Soil properties and formation across the SCP–Scarp study area
    • Spatial patterns and variability (using SOC/pH/Clay/AWCmaps and related layers)
    • Dynamic processes (water, carbon, nutrients) in the soil-plant-atmosphere continuum
  2. Evidence-based reasoning
    • Use principles from workshops and tutorials
    • Support claims with spatial outputs (maps) and established concepts
    • Make explicit links between patterns and processes

What makes a strong Landscape Management Brief? (2)

  1. Clear communication
    • Accessible to non-specialist but technically literate audiences
    • Logical structure, clear maps and conceptual figures
    • Explicit, realistic recommendations
  2. Integration
    • Connect soil, water, vegetation, and management actions
    • Consider timescales and feedbacks (including disturbance and recovery)
    • Incorporate Indigenous knowledge (once covered)

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