Views of a restored peatland from the past, underground, and future cedar swamp

The Hydrologic Understory is an integrated research and extension project that explores groundwater flowpaths, surface water mixing, underground thermal regimes and soil moisture monitoring to map out the interconnected web of hydrology and ecology beneath the surface ultimately helping guide management of wetlands, including attracting desirable native species, creating and maintaining habitat for rare and endangered species including Atlantic White Cedar, cold water fishes and optimal water quality. 

In this cranberry-bog-turned-restored-freshwater-wetland, the largest in Massachusetts, we are exploring first principles measurements of hydrologic parameters to help guide restoration practices and management of this former peatland. One of the most basic, defining metrics of a wetland is, as the name implies, its wetness. We explore time series of temperature and water elevation data at a restoration site from retired farm, through restoration, and wetland development. While single measurements can indicate the groundwater table elevation below the ground surface at one time (a useful delineation metric), long time series can indicate how the site responds to storm flows, droughts, and other conditions; and how those responses are changed by restoration practice. Coupled with streamflow data, net water balance can be calculated as well as water residence time.  Temperature data serves as an indicator of thermal buffering capacity, the potential for development of thermal refugia for wildlife, and a tracer to locate influxes of groundwater. We use thermal imagery from UAS before and after restoration to map the surface expression of groundwater, and document the arc of change as the site rewilds. Distributed temperature sensing (DTS) buried at 10, 20 and 30 cm depths across the site allow for estimates of groundwater upwelling and soil moisture through time without creating additional subsurface disturbance.

Understanding long-term ecosystem dynamics in southeastern Massachusetts is achieved through a pollen and charcoal analysis of deep sediment cores spanning 9,140 years. This fire history record provides critical context for current restoration efforts of Atlantic White Cedar swamps, a rare and threatened ecosystem type in New England. Efforts are underway to co-steward these swamps together with local indigenous groups for whom they are critically important.

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, possess large accumulations of organic and hydric soils, and are currently sought-after by a statewide restoration program that aims to create a self-sustaining, resilient freshwater wetlands - promising hydrologic metrics are the first indicator of that success.