MICROBIAL BIOMASS AND ACTIVITY IN AREAS WITH DIFFERENT STAGES OF RIPARIAN FOREST RESTORATION

The restoration of riparian forests plays an important role in the soil and water protection, providing balance for the ecosystem. Soil microbial biomass and activity determination are useful tools to evaluate how agroecosystems respond to management and recovery strategies. Thus, the objective of this study was to evaluate changes in soil microbial biomass and activity in areas with different stages of riparian forests restoration. Soil samples were collected in riparian forests and agricultural systems located in the municipalities of Santa Terezinha de Itaipu and São Miguel do Iguaçu, Paraná state, in February (summer) and August (winter) in 2017, in six areas with different stages of restoration: 1. an undisturbed riparian forest; 2. restored riparian forest of 30 years of age; 3. restored riparian forest of 19 years of age; 4. restored riparian forest of 3 years of age; 5. initial riparian forest restoration (altered by pasture cultivation) and 6. Agricultural crop area (crop 2017: cultivation of maize crop). The samples were collected in the 0-10 cm layer and at each area, soil samples were collected in five points resulting in a total of 120 samples obtained. The carbon of the microbial biomass (CMB), the microbial respiration (MR) and the metabolic quotient (qCO2) were evaluated. Although the studied areas presented different values of CMB, MR and qCO2 with the seasonal variation (higher values in summer than in winter), there was a pattern of behavior in the comparison between the areas. In the summer and winter collections, the highest CMB value was observed in the native area, 546.17mg kg soil-1 and 526.93mg kg soil-1, respectively, followed by restored riparian forest of 30 years of age. However, MR and qCO2 were significantly higher in the agricultural crop area and initial riparian forest restoration in summer, 25.67 CO2 mg kg-1 day-1 and 77.34 qCO2 mgC-CO2 g-1 CMB h-1, and 50.24 CO2 mg kg-1 day-1 and qCO2 mgC-CO2 g-1 CMB h-1 in the winter. Changes in microbial attributes related to the different stages of riparian forest restoration were evident, and the restored riparian forest of 30 years of age had carbon values of microbial biomass, microbial respiration and metabolic quotient closest to the native forest.