Abundance and diversity of mesofauna in relation to minesoil properties after 14.6 years of revegetation with grasses

Global annual coal consumption may reach 8038 Mt. in 2025, resulting in continuous post-coal minesoils creation. In Brazil, the Candiota Mine represents the largest country's coal reserves and originates minesoils with high acidity, compaction, and depletion of organic carbon content and soil biological attributes, hindering the re-establishment of vegetation, mesofauna and microbial activity. This study aimed to assess mesofauna attributes and microbial activity in a minesoil restored for 14.6 years with perennial grasses in Candiota, and to explore their relationships with soil physical, chemical, and humus properties. Our previous research showed that Urochloa brizantha improved soil physical and chemical attributes more effectively than other grasses, suggesting stronger links between soil biology and these properties in this treatment. After 14.6 years of revegetation with Hemarthria altissima, Cynodon dactylon, Panicum maximum, Urochloa humidicola, and U. brizantha a series of minesoil biological, chemical and physical attributes (0.00–0.10 m layer) were assessed. Control site consisted of minesoil with spontaneous vegetation. U. brizantha treatment exhibited significantly lower bulk density (1.2 Mg m⁻³) and higher macroporosity (0.16 m³ m⁻³) and total porosity (0.48 m³ m⁻³) compared to C. dactylon (1.4 Mg m⁻³, 0.07 and 0.40 m³ m⁻³, respectively). Treatments did not differ regarding total carbon and carbon content in humic fractions, but mostly increased it compared to control. The total number of fauna individuals across treatments ranged from 596 (P. maximum) to 1146 (U. brizantha) at the litter-soil interface and from 1305 (H. altissima) to 2397 (U. brizantha) in the minesoil. In the control these numbers were lower (539 and 483, respectively). Mites and springtails predominated in all treatments at both litter-soil interface (34–50 % and 36–44 %, respectively) and minesoil (76–85 % and 9–17 %, respectively). Treatments did not differ regarding fauna diversity. Axis 1 and 2 of canonical correspondence analysis (CCA) explained 51 and 45 % of data set variability, respectively. Moreover, CCA revealed that interrelations of fauna and microbial biomass carbon with other soil attributes were unspecific for grass species, contradicting our hypothesis. Despite the outstanding performance of U. brizantha to ameliorate physical soil attributes, further research is required before one grass species is prioritized for restoration of minesoil ecological functions.