**1. Introduction**

In the last years, a 'Greening' or 'Regreening' of the Sahel was a most disputed topic. It mutated to a general discussion of regeneration potential of the ecosystems and the possibilities to find production modes for the necessary food production. Moreover, conservation and nature protection were discussed and great projects were initiated [1–13].

On the other side, the general political insecurity of the last 15 years supressed fieldwork and made an end to several initiatives. Many of the conservation projects are now classified as 'in suspense.' This stands especially for the big National Natural Parks in the Sahara of Niger and Chad [14–16] and more or less for the 'Great Green Wall' too [17, 18].

Thus, the reasoning on degradation or regeneration is often based on pure remote sensing without the necessary ground check or field work. In addition, for the case of Sahara-Sahel-complex, there is still a deep confusion on the nature and dynamics of ecosystems and landscapes as well as on their definitions. Limits and boundaries seem to be free floating – sometimes on an annual scale.

On this background, we will characterise the main ecosystems – landscapes of Sahara-Sahel by a general vegetation map in order to avoid further confusions. This should also work as a base to interpret palaeorecords. Furtheron, we will try to reconstruct the landscape evolution during the last 200 years. Finally, we will discuss the chances of measures of regeneration and conservation.
