A4.2.4—Ecosystem loss causes

Ecosystem loss is driven by habitat conversion, fragmentation, climate stress, acidification, pollution, and resource extraction that reduce species survival worldwide.

Exam analysis

Chance of appearing2%of analysed past papers

Latest appearanceNovember 2021

Most common paperPaper2

Typical marks1–2

Common command terms

Outline
Explain
Describe
Suggest

Scoring notes

Common mistake: Naming deforestation without explaining loss of habitat, food, shelter or breeding sites.

Recent exam appearances

November 2021Paper2 ["SL"] · TZ01(d)[ 3 ]A4.2.4—Ecosystem loss causes

November 2021Paper2 ["SL"] · TZ01(b)(i)[ 2 ]A4.2.4—Ecosystem loss causes

November 2021Paper2 ["SL"] · TZ0(ii)[ 1 ]A4.2.4—Ecosystem loss causes

May 2019Paper3 ["SL"] · TZ214(b)[ 2 ]A4.2.4—Ecosystem loss causes

November 2017Paper3 ["SL"] · TZ014(c)[ 1 ]A4.2.4—Ecosystem loss causes

Coverage 2017–2021 · Updated 15 Jul 2026

Ecosystem loss includes conversion, degradation and fragmentation. These change habitat structure and abiotic conditions, disrupt interactions and nutrient cycling, and reduce resilience.

Borneo rainforest pressures and Great Barrier Reef pressures lead to loss of terrestrial and marine community structure.

Ecosystem	Pressures	Biological pathway
Borneo mixed dipterocarp forest	logging, fire and oil-palm conversion	canopy and habitat loss → fragmentation → decline of forest communities
Great Barrier Reef	warming, falling pH, runoff and fishing	coral stress and mortality → habitat loss → reef-community decline

Focus	Measure the state or trend	Diagnose the driver	Match the action	Monitor recovery
genetic diversity	allelic variation, heterozygosity, population size	isolation, bottleneck or inbreeding	reconnect populations or manage breeding	genetic diversity and effective population size
species diversity	richness, evenness, abundance, extinction risk	exploitation, invasive species or habitat change	protect, control threats, breed or reintroduce	abundance, recruitment and distribution
ecosystem diversity/function	habitat extent, condition and process indicators	conversion, fragmentation, pollution or climate stress	protect, restore and reconnect habitat	structure, processes and resilience

Define the level → establish a comparable trend → identify the causal driver → choose an action at the same scale → test whether biological recovery follows.

No single index or intervention is sufficient: species counts can miss evenness, genetic erosion and ecosystem dysfunction, while a reserve can fail without connectivity, enforcement or threat removal.

[ 1 ]

The satellite images show changes in the area covered by forest, much of which is mixed dipterocarp forest, on the island of Borneo in Southeast Asia.

Which human activities are most likely to have caused the changes shown in the map?

Concept essentials

Deforestation reduces biodiversity by removing habitat and essential resources.
Fragmentation can isolate populations and increase edge effects within remaining habitat.
Rising sea temperatures and ocean acidification can damage coral reef ecosystems.
Logging and plantation agriculture are major drivers of mixed dipterocarp forest loss.