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NotesESSTopic 2.1Ecosystems as open systems
Back to ESS Topics
2.1.205 min read

Ecosystems as open systems

IB Environmental Systems and Societies • Unit 2

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Contents

  • An ecosystem: a community and its surroundings
  • Energy and matter in and out
  • Neighbouring ecosystems are linked
  • Exam-style question
A community and its surroundings: An ecosystem is a community and the physical environment with which it interacts.

The points to remember

  • An ecosystem is a community plus the physical environment it interacts with.
  • Living parts are biotic; non-living parts (soil, water, air, light, temperature) are abiotic.
  • Name a local ecosystem precisely: 'deciduous woodland', 'freshwater pond', 'salt marsh'.
  • Not enough: a broad group ('terrestrial', 'freshwater ecosystem') or just 'forest'.
  • Not an ecosystem: a biome ('taiga biome') is a much larger, worldwide group.
  • Ecosystems come in any size: a pond, a wood, a whole reef.
Remember it as: Community + surroundings = ecosystem. Name it exactly, never just 'forest'.

Precise enough

  • Temperate deciduous woodland
  • Freshwater pond
  • Salt marsh

Too broad

  • Forest
  • Terrestrial ecosystem
  • Taiga biome

Real example: Richmond Park, London, holds several ecosystems side by side: acid grassland, ancient oak woodland and freshwater ponds.

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Open and closed systems were met in 1.2.5. Every real ecosystem is open.

The points to remember: open systems

  • Ecosystems are open systems: both energy and matter cross their boundary.
  • Energy enters as sunlight and leaves as heat.
  • Matter enters and leaves: water, nutrients and soil, gases, and living things.
  • Living things cross too: seeds blown in, animals migrating or wandering out.
  • We draw the boundary, so what counts as an input depends on where we draw it.
Remember it as: Sunlight in, heat out. Water, nutrients, gases and living things in and out.
An oak woodland inside a dashed boundary. In: sunlight (energy), rain, seeds blown in, birds arriving. Out: heat (energy), water in streams, leaves blown out, deer leaving
Energy and matter both cross the boundary: an open system.

Real example: in a wood, rain falls in and leaves by streams; jays carry acorns in, and deer wander out to feed in fields.

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Neighbours share their flows: Along warm coasts, mangroves, seagrass and coral reefs sit side by side and pass matter and energy between them.

The points to remember: when one ecosystem is lost

  • Open ecosystems are linked, so losing one affects its neighbours.
  • Less protection from storm waves and currents for the ecosystem behind it.
  • Fewer nursery and breeding grounds for species that move between them.
  • Less organic matter and nutrients passed on to the neighbour.
  • Cloudier water without filtering or trapping, so less light for photosynthesis.
  • Species move in, raising competition; fewer grazing fish can even mean more seagrass.
  • Fewer tourists, so less money to protect the neighbouring ecosystem.
Diagram, top to bottom: land and rivers, mangrove forest, seagrass meadow, coral reef, open sea. Blue arrows downwards: mud and nutrients from farms; fallen leaves and young fish move out; young fish move on to the reef; plankton and larvae drift out. Amber dashed arrows upwards: reef breaks storm waves; waves slowed by seagrass; storm waves weakened. Blue arrow up from the sea: fish and turtles visit to feed
What passes between land, mangroves, seagrass, the reef and the open sea.
Say what happens to the neighbour: 'Biodiversity is lost' or 'the water is cloudier' alone is not enough: say how it harms the neighbouring ecosystem.

Real example: in the Florida Keys, USA, mangroves, seagrass meadows and coral reefs lie side by side, and many reef fish, such as grey snapper, grow up in the mangroves and seagrass first.

How this comes up: Paper 1 [1]: identify an ecosystem from a map. Paper 1 [2]: outline how losing one ecosystem affects its neighbour.
Diagram, top to bottom: land and rivers, mangrove forest, seagrass meadow, coral reef, open sea. Blue arrows downwards: mud and nutrients from farms; fallen leaves and young fish move out; young fish move on to the reef; plankton and larvae drift out. Amber dashed arrows upwards: reef breaks storm waves; waves slowed by seagrass; storm waves weakened. Blue arrow up from the sea: fish and turtles visit to feed
Figure 1: the links between the coastal ecosystems.
IB-style questionOutline[2 marks]

Figure 1 shows how mangroves, seagrass and a coral reef are linked along a tropical coast. Mangroves are being cleared to build shrimp farms.

With reference to Figure 1, outline how loss of the mangrove forest could impact the seagrass meadow.

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Scientists describe a lake as an open system.

the term open system.
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Related ESS Topics

Continue learning with these related topics from the same unit:

2.1.1The biosphere
2.1.2Organisms and species
2.1.3Classification
2.1.4Identification of organisms
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