Powys Nature Recovery Plan, Ecological Networks, Existing Heathland Network.

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Legend:

Lower contribution to the heathland network.

Higher contribution to the heathland network.

Core habitat.

Stepping stone.

Not part of the heathland network.

Vice county boundaries.

Ecosystem function:

Opportunities to enhance the heathland network.


What the map shows:

The map shows core habitat patches in bright green, stepping stone habitat in light pink and the supporting habitat along a gradient of purple, with fainter colours showing areas that are more difficult for species associated with the network to reach.


How to interpret the map:

Three types of habitats are shown on the map: Core habitats - patches of semi-natural habitat that are large enough to maintain a stable population of species, as well as their genetic diversity; Supporting habitats - habitats surrounding the core habitats, which provide conditions that allow species associated with the core habitats to travel through them; and Stepping stones - patches of habitat of the same type as the core habitats, but too small to maintain populations of specialist species; these can be used by some species to cross from one patch of core habitat to another. When targeting management action, consider improving the connectivity between core habitats; increasing the size of current stepping stones or creating core habitat in areas well connected to other patches of core habitat.


Why it is important:

Areas of core habitat within a habitat network benefit overall biodiversity levels, as the connections with other patches of core habitat enhances genetic diversity and, therefore, adaptability when faced with changing environmental conditions, e.g. climate change or changes in management. This helps to prevent local extinctions and, should local extinctions occur, facilitates re- colonisation.


How the map was created:

Network modelling utilises a pseudo-species, a species that depends on the core habitat for reproduction and/or food, but is not a pure specialist (Watts et al., 2010). Based on this pseudo species, a maximum dispersal distance is defined; this distance approximates how far the species would disperse under ideal conditions. The maximum dispersal distance used by the heathland species in this project is 600m (based on Bowe et al., 2015). How far a species will be able to travel depends on the type of supporting habitat. It is easier for a heathland species to travel through bog habitats than through arable land or coniferous plantations. This concept is expressed through permeability scores, which are then considered in a cost-distance model.