Enhancing wetland protection by defining eco-hydrological thresholds of disturbance

Session: 34. - Aquatic Habitat Evaluation and Assessment

Neil Taylor, Toronto and Region Conservation Authority, [email protected]
Lyndsay Cartwright, Toronto and Region Conservation Authority, [email protected]

Abstract

A network of 14 palustrine headwater wetlands in reference condition was monitored over a 5-year period to determine the range of natural hydrological variability within these wetlands.  A spreadsheet-based tool was developed based on the Indicators of Hydrologic Alteration (The Nature Conservancy, 2009) to analyze the monitored wetland hydroperiod data on an annual basis. The annual metrics generated by this tool were then analyzed to compare sites grouped into mature forested swamps, shrub thicket swamps, and open marshes, and to determine whether inter-annual variability in hydrology exceeded inter-community variability.  PCA was used to visualize the results and demonstrated that, while there was some tendency towards spatial clustering within wetland community types, there were also significant outliers within each community type.  The depth of water during the early growing season, when water levels reach their annual maximum, appeared to best differentiate community types.  The results from this work can help ecologists determine when a change in water balance, resulting either from human activities or from a changing climate, might be expected to cross an eco-hydrological threshold that will cause the ecosystem to shift to a different community or towards a non-wetland state.  

1. Keyword
wetlands

2. Keyword
hydrologic budget

3. Keyword
management

4. Additional Keyword
ecological thresholds