Assessing the restoration of a seasonally flooded riparian forest through soil carbon and nitrogen cycling indicators and soil microbial communities

The restoration of a six-year-old, seasonally flooded riparian forest planted with woody species native to the Brazilian Cerrado biome within a buffer zone system was evaluated based on soil carbon and nitrogen cycling parameters and soil microbial communities. Soil organic carbon, humic and fulvic acids, phospholipid fatty acid profiles of total bacteria and fungi, and selected functional microbial groups, such as aerobic/anaerobic and denitrifying communities, were used as indicators of soil quality and fertility. Restoration was progressing towards the soil conditions of a preserved riparian forest (PS) compared to a disturbed site (DS). However, a higher soil ammonium concentration was observed at the experimental site (ES) and DS than at PS, which was attributed to impaired nitrification due to periodic flooding. Principal component analysis confirmed that soil organic matter, cation exchange capacity, NO3-, and the denitrifying, anaerobic/aerobic, actinomycetes, and Gram-negative groups are suitable indicators for riparian site restoration. In contrast, soil NH4+ accumulation emerged as the main environmental impact hindering riparian forest recovery.