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

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Legend:

Lower contribution to the grassland network.

Higher contribution to the grassland network.

Core habitat.

Stepping stone.

Not part of the grassland network.

Vice county boundaries.

Ecosystem function:

Ecological network for grassland species.


What the map shows:

The map shows core and stepping stone habitat in dark brown and opportunities to enhance the grassland networks in shades of light orange. Darker shades indicate areas that are considered to be stronger opportunities.


How to interpret the map:

The map shows core habitat patches in black, stepping stone habitat in brown and the supporting habitat along a gradient of orange, 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 grassland species in this project is 500m (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 grassland species to travel through areas of scattered bracken than through urban or intensively farmed habitats. This concept is expressed through permeability scores, which are then considered in a cost-distance model.