Some habitats have turned out to be more threatened than others. This is partly reflected in the distribution of extinct, acutely threatened and vulnerable species related to the different areas. Most threatened are heathland, pastures, fringes and slopes open to the light, after which come meadows, marshes, bogs and springs, and finally forest areas. Lakes, streams and rivers are less threatened, and least threatened are the sea and salt-influenced coastal communities and the dunes. The major threats can be defined as overgrowing, planting, cultivation, draining, pollution and urbanisation.
Sulphur dioxide, nitrogen pollution and acidification are the most important reasons.