AbstractWe studied physical and chemical conditions and the crustacean communities in temporary ponds in a military area in South Germany. All ponds were formed by driving of tanks. They were turbid, without higher aquatic plants but contained a unique crustacean community with endangered species such as the anostracanBranchipus schaefferi, the copepodsCyclops furciferandMetacyclops minutusand the cladoceransDaphnia obtusa, MoinabrachiataandMacrothrix hirsuticornis. Branchipuswas only present in ponds which dried out and where driving occurred. Ponds which did not dry out and where driving events were rare or did not take place were devoid ofBranchipus. Physical and chemical conditions were similar in ponds with and withoutBranchipus. Day‐night fluctuations of temperature were up to 15 °C in summer. Conductivity was 200–300 μS cm−1, hardness ranged between 2 and 3.5 meq 1−1, alcalinity between 1 and 3 meq 1−1, pH between 7.5 and 9, dissolved phosphorus was<20 μg 1−1, concentration of nitrogen was60% in the ponds except one pond where concentrations of nutrients and conductivity were somewhat higher. When driving of tanks had been stopped the number and size of the ponds decreased and their character changed.Branchipus schaefferiand other endangered species disappeared and more but common, benthic species such as the cladoceranChydorus sphaericusand the copepodsMegacyclops viridisandEucyclops serrulatusgained importance.Branchipus schaefferiis now close to extinction. Conductivity, hardness, alcalinity increased while pH decreased probably because algae were replaced by marsh plants. We conclude that driving of tanks raised clay particles, prevented the growth of higher aquatic vegetation and condensed the bottom sediments. All this was necessary to keep the ponds in an early stage of succession thus providing conditions necessary to ma