The word ‘habitat’ can be used to describe the geology, soils, land cover (e.g. vegetation) and management wherever you are, from urban habitats to semi-natural woodland, upland moorland to open sea. Some habitats will generally be more biodiverse that others. Intensively-farmed fields, such as improved grassland pastures, are often managed in a way that prevents the growth of all but the intended sown plant species, whereas semi- or unimproved grasslands are often rich in wildflowers and support a huge number of insects and other animals. Some habitats take a longer time to develop than others. Ancient Woodland may take at least four hundred years to mature, so in today’s terms it is considered irreplaceable. Some habitats have a smaller distribution than others, or are in decline, and may support rarer species. Purple Moor-grass and Rush Pastures (including our distinctive ‘Culm Grassland’ in the east of Cornwall) is a Priority Habitat that has suffered in previous years from land drainage and nutrient inputs, causing this already restricted habitat to be replaced.
For all of these reasons, we can assign a greater value to some habitats than others. Conservation organisations have long know the value of our most important habitats and have taken steps to protect the most valuable sites by assigning designations, such as Sites of Special Scientific Interest (SSSIs). For the average person, the value of a habitat may relate to the simple joy of walking through an oak woodland listening to the birdsong, which has its mental and physical benefits (as described in Access). On a more intricate level, healthy and diverse habitats make for healthy ecosystems, benefitting everything from food production to cleaner air.
The highest-scoring sites will be covered, at least partly, by a conservation designation and contain a large proportion of semi-natural habitats, particularly Priority Habitats.
Low-scoring sites will include heavily-managed sites (e.g. farms) that may still contain some valuable habitats, but in a lower proportion compared to other sites.