Habitat state values

The 'value' of the particular state of a habitat, in terms of its importance, can be identified as a combination of its ecological values, including type of vegetation or animal interests. Similarly, values associated with sea defence capability and social 'values' including recreation and landscape can be derived. Moving from one state to another changes these 'values'. By using the state evaluation models, decision-makers can come to understand how the system moves from one state to another, whether by natural or human-induced change, and what impact such change has on the 'value' of the site.

Grazing on saltmarsh - an example of changing states

Introducing grazing on a formerly ungrazed saltmarsh can reduce the structure of the vegetation and change its species composition. This in turn may result in a change in value from one where the biodiversity is represented by breeding birds and invertebrates to one where wintering ducks and geese are predominant.

Caption: A heavily sheep-grazed saltmarsh in western Ireland.

Caveat: The use of 'value' and 'cost' in this context should not be taken to imply a fixed, quantifiable or objective measurement. Indeed, the 'value' to be assigned to any of the factors will be fundamentally influenced by, among other things, the type of user, the nature of the problem and the resources available to effect a change. For this reason, the Guide cannot provide a table of pre-calculated habitat values. Rather, it provides an indication of what factors to consider when deriving a 'value' in a given situation.

Comment: Links to the State and Value models for each habitat are provided.