Combining indicator species and key environmental and management factors to predict restoration success of degraded ecosystems

When evaluating the success or failure of ecological restoration projects, practitioners need to verify success within the first few years of the monitoring process to apply corrective measures if necessary or to reclaim environmental down payment where required. This could be achieved with ecological indicators, if they can be easily and routinely measured and are representative of the complexity of the restored ecosystems. We used peatlands restored after horticultural peat extraction in eastern Canada to test a methodological approach that predicts restoration success early after restoration implementation. The goal of restoration of these extracted peatlands is to re-establish a moss carpet typically dominated by Sphagnum mosses, the main peat-accumulating plant group in these northern ecosystems. Vegetation in a total of 152 plots in 41 peatlands restored after peat extraction activities and distributed across a span of 600 km was monitored every 2 years since the third year after restoration. The plots were clustered in three restoration outcome categories: Sphagnum-dominated, bare peat-dominated and Polytrichum-dominated, according to their characteristic vegetation composition at the time of the latest survey for each plot (4-11 years since restoration). Second, vegetation composition in the same plots from the earliest survey, 3 years since restoration, and key environmental and management variables such as summer temperature, effectiveness of ditch blockage, season of restoration works and delay in P fertilization were analyzed using linear discriminant analysis (LDA) to obtain the combination of parameters that best discriminated between the restoration outcome categories. LDA correctly classified 71% of the plots of a calibration database (for which 75% of the sectors were used) and 75% of a validation database (for which 25% of the sectors were used) into the three categories. The obtained LDA models can be used to allocate new plots to one of the restoration outcome categories by providing a series of linear equations (classification functions) that are computed from the combination of ecological indicators. One additional and recently restored peatland was used to illustrate application of these equations of the LDA model to predict future restoration outcome and subsequently adapt management strategies. Such a LDA model provides an unequivocal (i.e., one new plot assigned to one and only one restoration outcome category) prediction of success based on multiple but simple, easily recognizable indicators and spares managers the complex task of interpreting many individual predictors for establishing a clear diagnosis. (C) 2014 Elsevier Ltd. All rights reserved.