An assessment of early-stage forest restoration outcomes and the instruments used to evaluate ecosystem recovery

Abstract

Ecological restoration projects are considered successful when identified goals are achieved and the ecosystem progresses along a predicted successional trajectory. My study examined the progress of early-stage forest restoration projects within the Regional Municipality of Waterloo to determine the variables that affect early successional trajectories. The study was undertaken to gain further insight into the most appropriate methods to use in the evaluation of restoration outcomes and to provide some useful recommendations for restoration ecologists and practitioners. <br /><br /> Between April-October 2005 and April 2006, data were collected using a stratified random sampling technique and the wandering-quarter method to evaluate herbaceous vegetation, regenerating woody vegetation and mature trees at 7 forest restoration sites within the Regional Municipality of Waterloo. The Regional Municipality of Waterloo was selected as the study area because it has restoration projects established in forested ecosystems and the Region is typical of southern Ontario, i. e. , forest ecosystems have been disturbed by urban and agricultural activities and require ecological restoration. <br /><br /> A nested Analysis of Variance was used to test the responses of various herbaceous and woody vegetation parameters to the restoration site, restoration technique nested within the restoration site, and transects nested within the restoration technique. Site location, restoration technique, and restoration transect all appear to significantly affect restoration progress for some structural metrics. Species diversity (measured by the Shannon-Wiener Index) was significantly affected by the restoration site (p<0. 01) and transect nested within the restoration technique (p<0. 01). For some sites, differences in diversity among transects are expected to diminish as restoration proceeds and natural succession progresses. For heavily degraded sites, however, that exhibit low native plant species diversity may require a more intensive restoration strategy to improve local conditions. Density was significantly affected by the restoration site (p<0. 001) and the restoration technique nested within the site (p<0. 01). Sites without a closed forest canopy had higher densities of plants for all sampling guilds. The percentage of native species was significantly affected by the restoration site (p<0. 01) and the restoration technique nested with the site (p<0. 05). Sites that were restored from degraded forest conditions, rather than from old fields, exhibited significantly higher percentages of native plants for all sampling guilds. <br /><br /> Generally, sites with high species diversity, a high percentage of native species, and high density indicated that ecological restoration was progressing on the predicted successional trajectories and should lead to a successful restoration as time goes on. Results indicate that 4 out of 7 restoration sites are progressing as expected, i. e. , towards the predetermined restoration goal. The remaining 3 restoration sites may recover over time, but will most likely require additional restoration measures to achieve a desirable long-term outcome. At early-stages, structural measures appear to be useful indicators for evaluating the progress of restoration. In order for a restoring ecosystem to follow along an expected trajectory, formative evaluation must occur throughout the process to ensure that positive outcomes are achieved along the way. The study concludes that evaluating the progress of forest restoration projects at an early stage could greatly improve the long-term success of restoration outcomes by offering opportunities for mid-course correction and to learn from past mistakes.