Are plant traits a practical indicator for monitoring ecological restoration projects?

In order to restore ecosystems, we must have reliable monitoring indicators to identify the success of ecological restoration, and make effective management decisions. Indicators must be simple and inexpensive to measure to allow for practical industry use, account for ecological and environmental change, and provide direction to ecosystem managers. Trait-based monitoring approaches have been proposed as an alternative measure to traditional vegetation monitoring indicators (e.g. measures of species diversity), as they provide more information about the function of an ecosystem and their abiotic-biotic interactions. The literature indicates that plant functional traits, which explain how an organism acquires, processes and invests in resources, may be an ideal monitoring indicator. I examined the practical application of plant traits to assess restoration success in a phragmites managed Great Lakes Coastal Wetland, in the face of significant management and ecological variability. Two traits often cited in the literature, specific leaf area and leaf dry matter content, were measured in open marsh and three created ponds of different ages, and in plots treated with glyphosate and plots left un-treated. Non-parametric Mann-Whitney U and Kruskal Wallis tests were used to compare the community weighted mean trait values of ponds and open marsh, and between herbicide treatment groups. Notable results included an increase in specific leaf area after herbicide treatment, and a decrease in leaf dry matter content, suggesting that traits promoting biomass production may be favoured after herbicide treatment. This is consistent with previous studies comparing weighted means after management action, as well as in successional trait studies. However, it will be important to consistently monitor invasive species presence and management actions, in order to confirm that trait changes are due to herbicide treatment. No statistically significant differences were found between ponds and open marsh for specific leaf area, and leaf dry matter content only differing significantly in one pond. Possible explanations for this lack of change and the variable changes between ponds include intraspecific variation, environmental factors like water level fluctuations, and management variation between ponds. To conclude, the use of leaf traits, and plant traits in general, are possible as a restoration monitoring measure, but their use is highly site specific. They are best suited in situations where variability is low; where they can be compared against a measureable environmental gradient or a well identified management regime, two factors that do not always exist in a practical resource management context. Time also plays a role in the application of traits to restoration projects; the more traits that can be measured, and more resources allocated to the understanding and application of additional functional diversity indices, the more valuable their use. Future research and management opportunities include the integration of trait-based monitoring measures into diversity monitoring regimes, the exploration of traits as a restoration design measure to combat exotic species invasions, and testing ecological indicator criteria on other key traits (e.g. belowground traits, regenerative traits) to asses their potential as monitoring measures for future restoration project monitoring