The connections

The parts (the core areas, matrix and movement routes) can form a network if they are connected in some way.  But what appears to be connected to us may not be linked for another species - so how are they joined together and how do you know when you've got a network? 

The parts of a network can be connected or expanded either structurally or functionally. See below for more information.

Structural connectivity

A landscape is described as structurally connected when areas of habitat are physically joined together by a linking area of a similar habitat type. You can usually see structural connectivity on a map or aerial photo as a block of habitat.

However, just because two areas of habitat are structurally connected, it doesn't necessarily follow that all species will be comfortable, or capable of moving between them.  For example, the connecting linkage may be too small for an animal to feel safe passing along it, or it may receive too much direct sunlight for some plant species to thrive there.  So although there may be a structural connection between two habitat patches, visible as a line on a map, it may not actually constitute a network.

Functional connectivity

An alternative consideration is to establish whether a landscape is functionally connected. This may not look like a network on a map or aerial photo, but if a plant or animal can move between the different patches they're described as functionally connected. For example, an animal could be able to move through an area of suitably managed matrix / surrounding land - resulting in the habitat patches being connected in practice for that particular species.

However, functional connectivity is more difficult to assess - you need to know what sort of landscapes a particular species could be expected to move through and for what distance. That information then needs to be linked with the current land-use, so you can see where functional connectivity exists and where it doesn't. Information on the different species and their movement characteristics isn't always available and because this type of network is more complex to assess, it's usually done with a computer model. These models are usually species specific and what works well for one species may not work for another. Some examples of these models and their applications can be found on the modelling pages.

The most suitable type of connection will vary with different species. Some faster moving animal species may benefit from functional connectivity, but some slower moving species may need relatively large and stable physical connections in order to move from one habitat area to another.

It's important to remember that connectivity can apply to people as well. If you're looking to create a green network, you might also need to consider how to connect different areas of green space so that people can move between them. For example, there's no point having a beautiful park with lots of paths for people to walk around if they can't get there because they'd have to travel across a six lane motorway. And the permeability of land can vary for different people - someone pushing a large buggy might not be able to use a footbridge with lots of steps, so it may form an impermeable barrier, even though other people might be able to cross it very easily.