3.3 Fragmentation, resistance and resilience

We can use resistance and resilience in relation to individual species and to ecosystems. The term fragmentation applies to species and habitat.

Resistance is the ability to maintain a population or an ecosystem despite changes in conditions. Resilience is the ability to ‘bounce back’ from changes in population (for a species) or conditions (ecosystem). Fragmentation happens as populations of species or ecosystems become more isolated from each other (or fragmented). Fragmentation means that species or ecosystems are more vulnerable to changes in environmental conditions.

Fragmentation is important when we consider resistance and resilience. This is because as a species or population and its range become fragmented, so this changes the population's ability to resist and bounce back from change. This also holds for the habitats and ecosystems.

Let's look back at our grouse, which is already finding it hard to make a living at the edge of its niche. We can see that rapidly changing climates can lead to localised extinctions.

While the disappearance of sub-Arctic habitats and species from the UK is troubling, habitat and populations will persist in other areas. See the example of the black grouse in Finland.

These are localised extinctions, they are serious, but a far greater concern is the extinction of species that are endemic (only found in) the UK. The Scottish crossbill is the only endemic bird species in the UK and is in danger of global extinction.

The Scottish crossbill has a very restricted range and specific habitat requirements. It is largely dependent on Scots pine forest, though is occasionally found in conifer plantations, and is only found in the Scottish Highlands. Its dependence on Scots pine forest is associated with high altitudes and high latitudes. This means that the forests are likely to move northwards and upwards as temperatures increase. If the habitat within Scotland decreases or becomes more fragmented, then the Scottish crossbill is at risk of extinction.

Web resources regarding this topic:

  • Details of the UK Biodiversity Action Plan for this species

  • BirdLife species factsheet

  • Map of Scots pine distribution

  • General overview of extinction risk

3.2 The relevance of longitude, latitude and altitude

4 How apparently non-mobile organisms adapt to environmental change