## 1 Introduction
These wetlands are specifically drained for intensively managed pine plantations characterized by localized high spots and low spots due to site preparation which involves the formation of raised beds [31]. Raised beds, where trees are planted, increase seedling survival due to enhanced soil aeration and reduced competition from herbaceous and woody vegetation as young forests aggrade. Between the rows of beds, interbed regions exist which are lower in elevation compared to beds and are typically unmanaged zones within these forested plantations. To our knowledge, microbial enzyme activity has not been measured in relation to microtopographic features within drained wetlands under intensively managed pine silviculture. Soil depth is another type of spatial variability that influence microbial processes and soil C dynamics. In general, SOC and microbial biomass C (MBC) decreases with soil depth in upland and wetland soils [32; 33; 16; 34]. As C substrate quality and quantity available for microbial degradation are altered with soil depth, changes in extracellular enzyme activity are expected [35], but it can depend on how enzyme activity is normalized and be enzyme specific. Previous studies have indicated that enzyme activity rates calculated per g dry soil may not be comparable to the specific enzyme activity (enzyme activity per g SOC or MBC) and trends in enzyme activity with soil depth will vary between enzyme type and how enzyme activity is normalized [33; 35]. In one experiment, activity of peroxidase per unit mass of organic matter increased with depth while all other enzymes measured decreased (including \(\beta\)-glucosidase, cellobiohydrolase, xylosidase, N-acetylglucosamineaminidase, phenol oxidase and acid phosphatase) (Malaysian Peat Swamp Forest; [36]). Other studiesfound that \(\alpha\)-glucosidase and acid phosphatase per unit mass of MBC increased with soil depth while \(\beta\)-glucosidase, xylosidase, cellobiohydrolase and N-acetylglucosamine miniidase had no change with depth (Luquillo Critical Zone Observatory in northeastern Puerto Rico; [33]). Finally, [PERSON] et al. [34] found that in a hardwood swamp in the Canadian Great Lakes-St. Lawrence forest region, enzyme activity rates expressed per unit mass of dry soil (including \(\beta\)-glucosidase, cellobiohydrolase, N-acetylglucosamine, sulfatase and acid phosphatase) decreased with depth while no change with depth was detected for phenol oxidase or peroxidase activity. However, few studies have measured specific enzyme activity (normalized by both SOC and MBC) in conjunction with enzyme rates normalized by soil weight, and over such a wide range of soil organic and mineral horizons in these wetlands. Estimating specific enzyme activity may provide a more sensitive metric to detect changes in soil microbial activity and soil organic matter transformations under different land-use and with soil depth, as it accounts for changes in SOC or MBC content [35]. Not surprisingly, spatial heterogeneity in soil chemistry (e.g., pH, electron acceptor concentration), O\({}_{2}\) levels, soil microbial communities, and C substrates (e.g., presence of phenolics or humics, lignin concentrations) with soil depths also affects the types and activity of enzymes within the soil [19; 21; 37; 38; 39] and can be site specific. In the current study, our objective was to quantify microbial extracellular enzyme activity rates targeting a suite of SOC substrates, as well as that of one N-degrading enzyme, in natural and drained freshwater forested wetlands in a temperate region of coastal North Carolina, USA. Specifically, we investigated the effects of wetland drainage and spatial variability (microtopography and soil depth) on enzyme activity and if patterns in enzyme activity differed depending on how enzyme activity was normalized.