You have frequently heard of South Sea pearls, but the pearls of our freshwater pearl mussel from the Südheide are less well-known. Formerly the freshwater pearl mussels were widespread in the heath streams; today they are threatened by extinction. There is only one growing population left in Central Europe, which is found in the Südheide nature park, in the Lutter and Lachte streams. For this reason the Administrative District of Celle, which is not only the body responsible for the nature park but also a nature conservation authority, is here running a nature conservation project of representative importance for the country as a whole with the help of the State of Lower Saxony and the Federal Government.

The near-natural and nutrient-poor Örtze and Lachte streams provide together with their tributaries a habitat for many endangered and very sensitive plant and animal species. For this reason it is for example only allowed to go canoeing on the Örtze at certain times. The smaller streams may no longer be navigated. The otter, the brown trout and many others benefit from this. Some of the streams are so important for rare species threatened by extinction that they are protected – for example the Weesener Bach, which flows into the Örtze near Hermannsburg, or the Lutter and the Lachte.

The heath streams with their lowlands are even protected areas of importance for Germany and Europe. They form part of the European Natura 2000 protected area network.