Soil Enzyme Activity as Affected by Land-Use, Salinity, and Groundwater Fluctuations in Wetland Soils of the Prairie Pothole Region

Land-use change and climatic variability are significant drivers for the loss of ecosystem services and soil quality in the prairie pothole region (PPR) wetland systems. Land-use induced changes in groundwater table and salinity may influence biogeochemical processes facilitated by extracellular enzymes (EEs) involved in soil organic matter (SOM) decomposition. The effects of changing groundwater table and salinity on beta -glucosidase (BG), N-acetyl glucosaminidase (NAG), and alkaline phosphatase (AP) activities were assessed in wetland soils collected from three different adjacent riparian land-use practices in the PPR. In a microcosm study conducted over ten weeks, soils were treated with groundwater salinity (control, 6 mS cm(-1), and 12 mS cm(-1)) and declining groundwater table depths. Extracellular enzyme activities (EEAs) differed significantly (p <0.05) among soils from different land-uses and between groundwater table depths. The impact of groundwater salinity on soil EEAs were non-significant (p >0.05). Soil EEAs were significantly higher in soils from pasture, suggesting that the land-use effects resulted from background SOC and TN. Soil EEAs significantly (p <0.05) reduced under a deeper groundwater table depth, except reverse for BG in site B, indicated that the lowered groundwater table could lead to transitory drought stress for SOM decomposers.

Automated summary

Changes in groundwater table and salinity can significantly affect extracellular enzyme activities in wetland soils, with differences observed among different land-uses and groundwater depths. However, the impact of groundwater salinity on soil enzyme activities was found to be non-significant.