The aim of my PhD-thesis is to analyse the impact of overgrazing caused by intensive land use on the reptile community in the southern Kalahari and to understand the effect of changing habitats on population dynamics of the lizard Pedioplanis lineoocellata lineoocellata. My thesis consists of four major chapters which can be read independently, since every single chapter focus on a specific part of the influence of overgrazing on reptiles. Owing to the cumulative form of my thesis, some parts (e.g. methods) overlap to some extent. The first three chapters are submitted to scientific journals in cooperation with co-authors and the fourth chapter is in preparation. Because of the idea to submit all chapters to scientific journals my thesis has been written in the first person plural. Co-authors include my thesis advisor Prof. Dr. Florian Jeltsch, my thesis co-advisor Dr. Joh Henschel and Dr. Niels Blaum, who has been partners of fruitful discussion. Nonetheless, all findings presented here resulted from work that has been done independently by me.