Growth of the dominant macrophyte Carex aquatilis is inhibited in oil sands affected wetlands in Northern Alberta, Canada

Carex aquatilis could be a suitable species for wetland reclamation in mined boreal landscapes as those of the oil sands industry (Northern Alberta). We compared the performance of C. aquatilis plants established in oil sands industrial wetlands (directly affected by processed materials), on-site indirectly affected wetlands, and off-site natural wetlands. We studied leaf chemistry, fluorescence, gas exchange rates (net photosynthesis and transpiration rates), and morphological features of plants. Despite higher photochemistry efficiency in oil sands populations, plants did not channelize surplus energy into increased carbon assimilation rates. Oil sands populations registered lower culm heights and leaf lengths than natural populations. Plants growing in industrial wetlands were shorter and accumulated more sodium in leaves than plants from indirectly affected wetlands. Evidence indicated that C. aquatilis was a promising species for reclamation as it was tolerant to pollution. Though it survived, C. aquatilis, showed a restricted growth in the oil sands wetlands thereby possibly limiting carbon assimilation at the stand level. Oil sands wetlands amended with freshwater and established over non-industrial materials provided better growing conditions for C. aquatilis and demonstrated management tools for local reclamation efforts.

► Carex aquatilis had similar C assimilation but shorter leaves in oil sands than in natural wetlands.
► Restricted growth in oil sands wetlands might affect C assimilation at the stand level.
► Industrial wetlands had shorter plants than indirectly affected wetlands.
► Indirectly affected oil sands wetlands provided a better habitat for C. aquatilis.
► Reclamation success may be achieved in reclaimed oil sands wetlands.