A vegetation-based Index of Biotic Integrity to assess marsh reclamation success in the Alberta oil sands, Canada

Thousands of hectares of wetlands that are being destroyed by the oil sands mining process in Alberta, Canada must be compensated for. The reclamation requirements demand that compensatory wetlands meet a minimum level of ecological health, and be certified as successfully reclaimed. To assist the government in compliance monitoring we developed a vegetation-based Index of Biotic Integrity (vIBI), an ecological assessment tool that has been used in many jurisdictions to assess the ecological health of natural, degraded, or reclaimed wetlands. Our 45 study sites represented a gradient of physical and chemical stress, with 25 natural reference wetlands to represent the optimal outcome of reclamation, and 20 oil sands reclaimed wetlands. We assessed vegetation community attributes (metrics) for correlation with a physicochemical stress gradient, and incorporated the metrics with the highest correlations into two vIBI tools, an advanced vIBI (AvIBI) and a basic vIBI (BvIBI). A small fraction of all possible metrics had acceptable correlations (R2 > 0.25) with the stress gradient. Six metrics were incorporated into the AvIBI, and three metrics into the BvIBI. Both indexes were highly and significantly correlated with the stress gradient. The AvIBI requires in-depth vegetation assessment at each site and can be used to certify sites that display ecological health within the range of natural wetlands. The BvIBI requires little botanical expertise to implement, and can be used to chart reclamation progress. Both the AvIBI and BvIBI evaluated 14 of the 20 oil sands reclaimed wetlands as having low ecological health.