Introduction Background and RationalePeatlands are organic-rich wetlands that provide important ecosystem services at a range of spatial scales (Kimmel & Mander, 2010). Local hydrological setting is of central importance in determining the characteristics and functions of these ecosystems (Siegel & Glaser, 2006). Peatlands are characterized by waterlogged, anoxic conditions that suppress microbial decomposition, causing carbon to accumulate slowly but persistently over thousands of years in the form of partially decomposed plant detritus (Yu et al., 2010). Peatlands cover less than 3% of the Earth's land surface (Xu et al., 2018b) yet they are thought to store between approximately 500 and 600 Gt (5-6 × 10 17 g) of carbon (Müller & Joos, 2020;Page et al., 2011;Yu, 2011Yu, , 2012, equivalent to between approximately one sixth and one third of global soil carbon (Scharlemann et al., 2014). As well as being long-term carbon sinks, peatlands also emit greenhouse gases, particularly carbon dioxide (CO 2 ) and methane. Peatland greenhouse gas budgets are highly sensitive to surface wetness, and even modest changes in water-table depths can cause peatlands to switch between being net sinks and sources of greenhouse gases when measured in CO 2 -equivalent units (Evans et al., 2021;Günther et al., 2020). In some locations, water that drains from peat
Patterned bog and fen peatlands, which dominate the landscape in the Hudson Bay Lowlands (HBL), act as important water storage and conveyance features in this region. In spite of their hydrological importance, there are currently no studies that define and characterize the thresholds of bog‐fen‐tributary hydrological connectivity in the HBL or their relation to seasonal and annual changes in water fluxes. To this end, hydrological (i.e., streamflow and groundwater levels) and meteorological (i.e., precipitation, snow depth, evapotranspiration, and temperature) data were collected at a 4.8 km2bog‐fen‐tributary complex between 2007 and 2018. Connectivity thresholds were best characterized into three states (disconnected, connected, and high activity) that incorporated 41%, 47%, and 12% of the study period and 4%, 18%, and 78% of runoff, respectively. Runoff generally peaked in the spring due to snowmelt, while connectivity was highest in the peatlands in the fall months when precipitation exceeded evapotranspiration due to cooling temperatures. Warmer than average spring temperatures accelerated snowmelt rate faster than frost table thaw rate in the fen; this reduced the amount of meltwater that entered storage, increased drainage from bog to fen, and decreased overall connectivity in the unfrozen season. Cooler than average spring temperatures delayed bog connection and ground thaw; the late frost melt provided a source of water to the bogs after melt into the late spring and early summer. This study provides a basis for the modelling of peatland hydrological connectivity in the region in the drier conditions anticipated with climatic warming and regional resource extraction.
In northern Alberta, oil sands mining disturbs the boreal landscape, and reclamation to an 'equivalent land capability' is required. Industry is testing peatland construction as part of landscape reclamation. To determine if constructed peatlands can be selfsustaining, an understanding of the cycling of solutes in pore water and their interactions with dissolved organic carbon (DOC) is needed since DOC can represent an important carbon loss from peatlands. DOC is of interest due to its biotic origin and use by the microbial community and impact on carbon budgets. Additionally, salinity as a control on DOC quantity and quality may be important in oil sands reclaimed systems due to the likelihood of elevated sodium (Na + ) from saline groundwater input derived from tailings used to construct catchments, and natural sources. For this research, DOC concentration and quality, and Na + concentration were measured in the rooting zone (10 and 30 cm depth) of Nikanotee Fen to evaluate the role of Na + in DOC dynamics. DOC concentration and quality suggested that DOC in the fen was largely sourced from vegetation inputs, with quality also suggesting increases in vegetation inputs between years. Elevated Na + at 30 cm below ground surface corresponded with high concentrations of labile DOC. At 10 cm below ground surface, sampling location and temperature were the best predictors of DOC concentration and quality. With expected increases in Na + , increased production of mobile and microbially active DOC may lead to higher rates of carbon export.
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