Studying the complexity of the secondary succession process in the soil of restored open mine lignite areas; the role of chemical template

• A polyphasic approach was employed to study complexity during succession in soil.
• Soil variables were organized in four organizational spheres.
• Succession unfolded through distinct phases.
• Each phase is determined by the interplay among variables from the different spheres.
• The soil chemical background functions partially as template for the other spheres.

The unfolding of the secondary succession process in the soil of open mine areas reclaimed with Triticum aestivum (wheat) was analyzed by using a polyphasic approach. The study was conducted in five wheat fields with post-reclamation age 0, 5, 10, 15 and 20 years. Also data from control wheat fields outside the mining area were used. From the total of 77 variables 21 were used as surrogates to depict the succession course. These were organized in four spheres; (a) soil chemical composition (b) microbial community structure (c) catabolic activity of microbial community and (d) enzymatic activity in soil. To model the entire succession process the significant correlations among individual variables regardless of origin were analyzed by network analysis. Further, the results of the analysis informed the elaboration of a conceptual model by using Structural Equation Modeling (SEM). Although local configurations of variables were clearly imprinted on the network analysis phase graph, network parameters indicated dominance of the global network topology over local. The succession course is described as a moderately complex, well organized system, while the unfolding of the secondary processes in the four organization spheres followed almost co-directional pathways. The model formulated by SEM was a strongly reduced one, with many strong pair-wise relationships. Our results partially support the idea that the soil chemical background operates as a template overriding the structure of the microbial community and the enzymatic and catabolic activities.