Examining the Effects of Soil Moisture on Carex aquatilis Productivity in a Saline Reclaimed Fen in the Athabasca Oil Sands Region

Abstract

The Nikanotee fen is an experimental, constructed peatland in the region, established as a research site to develop strategies for future reclamation projects. Its main challenges include poor water quality caused by elevated salinity levels, which pose significant risks to the survival of its vegetation community. Carex aquatilis (C.aquatilis), a species of particular interest, is notable for its ability to tolerate diverse hydrochemical conditions, including high sodium concentrations. This study aimed to evaluate the effects of soil moisture on various chlorophyll fluorescence and gas exchange productivity parameters of C.aquatilis in the saline environment of the Nikanotee fen, with the goal of providing insights for its potential use in future reclamation projects in the AOSR. Through the use of a portable photosynthesis system, daily measurements of chlorophyll fluorescence (Fv/Fm, Fv’/Fm’, and φPSII) and gas exchange parameters (E, a, and Amax) were conducted to monitor the effects of soil moisture and water table depth in the varying moisture plots on C.aquatilis. The findings of this study determined that while varying moisture levels may not directly impact the productivity of C.aquatilis, they could influence its stress responses by enabling the species to develop adaptations suited to the surrounding moisture conditions. This is demonstrated by the statistically significant decreases in the stress ratio (Fv/Fm) during the heat wave observed in C.aquatilis grown in the ‘Moderate’ moisture plot compared to those in the ‘Dry’ and ‘Wet’ plots. Additionally, this study revealed that C.aquatilis may employ different salt tolerance mechanisms depending on moisture conditions. Plants grown in the ‘Wet’ moisture plots exhibited a higher sodium concentration in their aboveground biomass than in their belowground biomass compared to those in the ‘Dry’ and ‘Moderate’ plots, while still maintaining a statistically significantly higher φPSII and Amax values. These results demonstrate the resilience of C.aquatilis and its ability to sustain essential productivity levels for survival in increasingly reclaimed saline wetlands, such as the Nikanotee Fen.