Summarized results are broken down by general study category and as finalized results are published links to the final papers will be included. Please contact Joe Shannon with any questions.

Canopy Water Interactions

The loss of ash will lead to a large loss of transpiration in these sites, on average 88% of the water used by the canopy is used by ash. Throughfall increased immediately following the loss of the ash canopy but will continue to be affected by any vegetative response.

Carbon Fluxes

Higher soil CO2 flux was observed following the ash-cut treatment but there was no significant change in soil CH4. Unexpectedly high CH4 emissions were observed from lenticels on black ash stems, with a maximum difference between soil and stem flux occurring early in the growing season. Both soil and stem gas fluxes are driven by water levels and temperature.

Nitrogen Use and Availability

There was no change in soil N availability following treatment in the wetlands, while red maple and yellow birch showed reduced foliar N content post treatment. Future dominance of these wetlands by red maple or yellow birch will lead to changes in wetland N dynamics due to fundamental differences in foliar N content and N-use efficiency between black ash and its co-occurring species.

Understory Planting

Planting on available hummocks within the wetlands significantly increased seedling survival and following establishment year-to-year seedling survival rates were high. The four species with the highest 2-year survival rates were silver maple, American elm, American basswood, and northern white cedar.

Vegetative Community

An increase in total percent cover of herbaceous species was observed but response was delayed 2-3 years post treatment. There was a decreased regenerative capacity in black ash within ash-cut sites and an increased capacity in red maple. No clear trend was seen for overstory growth rates, but this response can also be expected to lag post treatment. Further data collection is planned.

Water Levels

No difference in water levels was observed between the control and treatment wetlands. All sites had increased water levels post treatment, corresponding to increased precipitation relative to pre-treatment conditions. A significant difference in seasonal drawdown was seen in treatment wetlands, likely the result of decreased water use following the loss of ash.

Water Source

The sites were found to be well connected to local groundwater systems and were in gaining conditions throughout most of the growing season. This input mitigates any treatment effect and responds strongly to inter-annual precipitation changes.

Water Yield, DOC, TDN

Water yield, and DOC and TDN export were highest in the spring, with the majority of the annual export for each factor occurring during high spring flows. The watersheds were also most responsive to rainfall during wetter periods (spring).