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Terrestrial ecosystems

This module considers the interactions between terrestrial organisms and their environments – that together form ecosystems, ranging from simple microbial communities to tropical rainforests. We could even consider earth as a whole ecosystem. The module will introduce you to key ecosystem concepts, and develop your understanding of the stability and resilience of ecosystems to disturbances such as disease and pollution. You’ll learn how ecosystem function depends on exchanges of water, energy and nutrients; and gain practical experience with current research techniques, including real-time monitoring and computer modelling. Finally, you’ll gain experience in writing professional-style reports on ecological systems.

What you will study

Understanding the structure and function of terrestrial ecosystems is the key to explaining how life on Earth has persisted in the past and how it might respond to change in the future. Ecosystem science takes a holistic view of organisms and the environment. The module reflects that view, illustrating the importance of interactions between the elements of ecosystems in determining the properties of the system as a whole.

The module is composed of four blocks that take you progressively from basic systems and processes up to the complexity of the global scale. An introductory block defines what the term ‘ecosystem’ means and presents a range of examples, describing their biotic (living) and abiotic (non-living) components. The second block addresses the cycling of energy, water, carbon and inorganic nutrients through these systems. You’ll reflect on how these flows control the type and number of organisms inhabiting the system, and how the presence of living organisms in turn affects the cycling of energy and matter. The third block explores the stability and resilience of ecosystems to both natural and human-induced disturbances such as fire, disease and environmental change. The final block looks at our planet as a whole to investigate the interdependence of the sub-systems within it.

Throughout, the module illustrates the four core concepts of definition, cycling, resilience and interdependence with examples from around the world, using the full range of online media. The module emphasises the nature of data obtained in environmental studies with its inherent variability. To understand our environment scientifically, manipulation and statistical interpretation of data are essential. It will introduce you to a number of statistical techniques, accessed via spreadsheets (including regression) to develop and enhance your professional skills in critically analysing statistical output.

Running through most of the module is a practical activity revolving around the monitoring and analysis of data on living trees. This will include basic observations of trees in your locality, and accessing and processing data from trees fitted with various monitoring devices on the OU campus and elsewhere. You’ll pool and jointly analyse data with other students on the module and gain assessment credit for reporting on your experiments.

Another theme of the module is the use of modelling. Predictive modelling of ecosystem response is now an essential tool in ecosystem science. The module illustrates different types of models, exploring their inputs, components and assumptions so you can correctly interpret the output. There are both spreadsheet-based ecological models and more complex Earth-system models that you’ll engage with to explore how different systems respond to external influences.

Entry requirements

We recommend you’ve passed one of the following:

  • Environmental science (S206 or SXF206), or the discontinued module S216
  • Questions in science (S111), Science:concepts and practice (S112), Environment: journeys through a changing world (U116), or one of the discontinued modules S103 or S104; plus an OU level 2 science module

You’ll need to be familiar with basic mathematics and statistics concepts from OU level 2 environment modules, including the basics of probability, statistical distributions and hypothesis testing. You’ll also need to be familiar with basic concepts from OU level 1 biology, notably photosynthesis and respiration. You’ll need no specific knowledge of modelling.

Check that you’re ready for S397 with our quiz Are You Ready For S397? You can find it on the S397 preparation website.

If you’re not sure you’re ready, talk to an adviser.

What's included

All study materials are available online, and are provided through the module website. Where possible, the materials will also be available in Microsoft Word format and as PDFs.

The following elements are all thoroughly integrated into the online materials:

  • online text covering core ecosystem science concepts and techniques
  • graphical and audio-visual supporting materials
  • interactive modelling exercises using simple spreadsheet models
  • more complex computer modelling exercises
  • practical experiments with real-time ecosystem monitoring systems
  • designing and performing ecological investigations
  • collaborative work through small online groups
  • small and larger group tutorials
  • integrated assessment
  • professional-style report writing.

Computing requirements

You’ll need broadband internet access and a desktop or laptop computer with an up-to-date version of Windows (10 or 11) or macOS Monterey or higher.

Any additional software will be provided or is generally freely available.

To join in spoken conversations in tutorials, we recommend a wired headset (headphones/earphones with a built-in microphone).

Our module websites comply with web standards, and any modern browser is suitable for most activities.

Our OU Study mobile app will operate on all current, supported versions of Android and iOS. It’s not available on Kindle.

It’s also possible to access some module materials on a mobile phone, tablet device or Chromebook. However, as you may be asked to install additional software or use certain applications, you’ll also require a desktop or laptop, as described above.

Teaching and assessment

Support from your tutor

Throughout your module studies, you’ll get help and support from your assigned module tutor. They’ll help you by:

  • Marking your assignments (TMAs) and providing detailed feedback for you to improve.
  • Guiding you to additional learning resources.
  • Providing individual guidance, whether that’s for general study skills or specific module content.
  • Facilitating online discussions between your fellow students, in the dedicated module and tutor group forums.

Module tutors also run online tutorials throughout the module. Where possible, recordings of online tutorials will be made available to students. While these tutorials won’t be compulsory for you to complete the module, you’re strongly encouraged to take part.


You can find the assessment details for this module in the facts box.

The module is assessed though TMAs and an end-of-module assessment involving activities integrated into the text and collected at the end of each block.

If you have a disability

The OU strives to make all aspects of study accessible to everyone and this Accessibility Statement outlines what studying S397 involves. You should use this information to inform your study preparations and any discussions with us about how we can meet your needs.

Future availability

Terrestrial ecosystems (S397) starts once a year – in October.

This page describes the module that will start in October 2024.

We expect it to start for the last time in October 2028.

Course work includes:

3 Tutor-marked assignments (TMAs)
End-of-module assessment