SPECIAL (CRANBERRY) SAUCE: GLACIAL GEOLOGY, LOTS OF WATER, OVERCOMING FARMING PRACTICE, AND TIME LEAD BOGS BACK TO WETLANDS

Freshwater wetlands are groundwater-dependent ecosystems that require groundwater for saturation, for wetland plants and creatures, for maintenance of wetland soils, and thermal buffering. With worldwide wetland area in decline for decades if not centuries, finding and restoring wetlands provides enormous ecosystem and public benefits, yet so often these projects fail to yield self-sustaining wetland ecosystems. One reason is that restored wetlands are often built in places that are neither wet enough nor possess the underlying geology to sustain them, and they dry out or require continual (expensive!) water inputs.

The challenge is figuring out how to un-deposit the anthropogenic layers from the surface (thick layers of sand, agricultural soils and their accompanying chemistry), or overcome the farming “plumbing” (berms, ditches and dams), to allow water to once more pool and collect on the surface and in the soil. We analyze levels and soil water chemistry from 18 piezometers in peat, farm-surface sand, plus surface streams and springs, for temperature, basic water chemistry and water isotopes. We measure soil moisture at four depths (0-30cm) and with a field probe (0-10cm) at 71 locations where surface vegetation is also monitored. We monitor temperature at root-zone depths of 10, 20 and 30 cm along a 900-meter-long transect using fiber optic DTS to identify moisture and GW conditions. Comparison of soil moisture data across a restored site and a pre-restoration site shows promise, hydrologic data confirm accumulation of groundwater throughout the site, and soil cores and excavation work have unearthed glacial clays and peat.

Massachusetts is turning cranberries into lemonade: while the cranberry farming industry is in decline owing to competition from less expensive land and more productive varietals in other locations, everything under historic cranberry farms is ripe for resilient wetland restoration projects. These low-lying water-rich areas are underlain by glacial geology (peats and clays) that are ideal for holding water, they possess historic seed banks of wetland plants and large accumulations of organic and hydric soils, and are currently sought-after by a statewide restoration program, for which these results provides critical information for restoration design, enabling practitioners to maximize the capture and residence time of groundwater inputs to sustain the future wetland.