4.1: How are habitats Classified?

Our long standing stable environments can be subdivided into habitat classifications based on the stage in the succession process intervention took place. Classifying habitat is a useful process in conservation as it provides benchmarks and standard practices that can be applied to any site of natural interest. Much of the ancient habitat that remains is designated with some form of legal protection which should prevent them from being degraded or lost altogether. If an area can be identified and classified as one of these ancient habitats then getting it designated for protection becomes easier.

Even if you are not a scientist or involved in the legal aspects of nature conservation and are just an enthusiastic amateur nature watcher, understanding habitat classification and the features of each classification can add interest and enjoyment to your recreation. It helps you understand an environment and how certain species make it their natural home. 

In the background, the primary habitat of the site, heath with a sub-habitat of a pond in the foreground. The 'lily' pads are a micro-habitat used by various invertebrates including damselflies and raft spiders

Primary Habitats:

There are various methods of classifying natural habitat and they all tend to start with a simple division into primary habitat types driven by the four stages of intervention to the succession process; woodland, scrub, grassland and heath. To these four two further primary groups can be added, freshwater environments (rivers, lakes, ponds, etc) and coastal (areas dominated by saline water and tidal movements).

Habitat still actively influenced by human activity is termed a 'brown field' site; this would include arable farmland, golf courses, quarries, gravel pits, roadside verges and so on. Brownfield sites are rarely eligible for protection but can be if protected species occur.

Sub-habitats:

Within each of these primary classes there are variations or sub-classes. One example of sub-habitats is mentioned above; freshwater habitats can, amongst other variants, be rivers, lakes, ponds, ditches, etc. 

On entering any site it should be quite obvious what primary classification applies but within any site there will usually be sub-divisions. For example, Hartland Moor, in the Purbeck area of Dorset is obviously heath but within that there are areas of dry heath, wet heath, mire and bog as well as the remnants of a tramway that once took clay to barges in Poole Harbour for transportation. Identifying these sub-habitats and their extent can be a bit more difficult and some knowledge of the features of each sub-habitat is required to be able to do this but, in general, it is not a difficult process.

Micro-habitats:

Within sub-habitats there may be small areas, possibly very small areas, that are quite unique and different from the conditions or habitat that surrounds them. For example, in woodland there may be a gap in the canopy where a standard tree fell during a storm. In this spot daylight will penetrate to the woodland floor at all times of the year and the absence of shade will mean more plants can grow. If the fallen tree is still present then that will become a microhabitat in its own right with an accumulation of fungi, mosses, lichen, ferns and possibly wood boring insects.

The classification of habitats is covered in greater detail in the complementary 'course'; Exploring Habitats.