Ecosystems can be complex and difficult to define and, more often than not, comprise a wide range of habitats; typically combining semi-natural, agricultural and non-natural components. This part of the website describes the main habitat groups in Wales, and the more important components of those habitats, some of which are now confined to small fragments and located in areas unsuitable for human land-use. The more common reference states and modified states of the habitat components are also described, illustrating how different pressures on the landscape have impacted on the habitats over varying time frames and led to the semi-natural habitats that we see today. The text includes information on some of the key management options and promotes the need for strategic restoration programmes that take full account of the associated biodiversity impacts.