Development of bacterial community during spontaneous succession on spoil heaps after brown coal mining

Abstract Changes in the abundance of bacteria and fungi and in the composition of bacterial communities during primary succession were investigated in a brown coal mine deposit area near Sokolov, the Czech Republic, using phospholipid fatty acids analysis, microarray and 16S rRNA gene sequencing. The study considered a chronosequence of sites undergoing spontaneous succession: 6-, 12-, 21- and 45-year-old and a 21-year-old site revegetated withAlnus glutinosa. During succession, organic carbon and the total nitrogen content increased while the pH and the C/N ratio decreased. Microbial biomass and bacterial diversity increased until 21 years and decreased later; bacteria dominated over fungi in the initial and late phases of succession. Bacterial community composition of the 6-year-old site with no vegetation cover largely differed from the older sites, especially by a higher content ofGammaproteobacteria,Cyanobacteria and someAlphaproteobacteria. Bacteria belonging to the generaAcidithiobacillus,Thiobacillus and related taxa, the CO2 and N2 fixers, dominated the community at this site. In the later phases, bacterial community development seemed to reflect more the changes in soil nutrient content and pH than vegetation with a decrease ofActinobacteria and an increase ofAcidobacteria. The site revegetated withA. glutinosa resembled the 45-year-old primary succession site and exhibited an even lower pH and C/N ratio, indicating that recultivation is able to accelerate soil development.