New England Salt Marsh Land Uses from the Colonial Period to Present
Susan Adamowicz, Ph.D.
Salt marshes play an unheralded yet critical role in providing for human needs and biodiversity. Archeologists and historians have well documented that Indigenous peoples yielded low environmental impact benefits from the marshes for over 5,000 years before the arrival of the colonists. Our discussion focuses on New England colonial and post-colonial use of the salt marshes.
The colonists primarily saw the salt marshes as sources of fodder and bedding for livestock. Beyond livestock feed and fodder, the colonists found the marshes a readily available source for meeting multiple agricultural needs. After composting, the salt marsh peat served as one of the best sources of enrichment materials for depleted upland fields. In the cold New England winters, the thatch made from marsh grass growing along creek banks was used to insulate drafty stone foundations and then repurposed to fertilize upland fields in the spring (1,2,3). By ditching the marsh, colonial farmers increased drier acreage suitable for fodder grass by creating better drainage. Thus began an agricultural tradition that lasted over 300 years (2,3). As time passed, ditching practices became more complex. During the 1700s, salt marsh hay farmers incorporated low earthen embankment systems with sluice box structures into the existing ditching infrastructural networks. This change increased the hay yield by limiting the number and the duration of tides flooding a given section of the salt marsh. In most New England salt marshes contemporary technologies have revealed three to four layers of these infrastructural networks.
The 1800s brought modern systematic agricultural practices to salt marshes. Farmers reworked the marsh ditching by deploying a new agrarian method called Marsh Reclamation and used high embankment systems with more advanced water control box valves (called "trunks") to reclaim large portions of the salt marsh high meadow zone into upland fields. A "properly" banked marsh could produce four tons per acre of English Hay (upland cultivated hay, sometimes referred to as Timothy or Herds grass), 1,600 bushels per acre of a slightly salt tolerant fodder beet called Mangel-Wurzel, and common vegetables such as Indian Corn and potatoes (4, 5, 1, 2, 3).
During the early 1900s, the increasing popularity of the ‘Horseless Carriage’ and the power of the internal combustion engine led to a decline in draft animal use. As horses and oxen became less common, so did the demand for fodder crops. As a result, labor-intensive salt marsh agriculture was largely abandoned. This abandonment and subsequent lack of maintenance caused widespread deterioration of the embankment systems and ditching networks (2). The resulting flooded conditions significantly increased mosquito populations and related health problems. To solve the mosquito problem, ditching renewed was as draining became the solution. The re-ditching era peaked in the late-1930s with the Works Progress Administration’s (WPA) aggressive campaign to drain the salt marshes along the North Atlantic coast.
During the late 1930s to the 1980s, the WPA ditches required regular maintenance to remove sediments and debris deposited by storms and tides, and labor gave way to mechanization. One such method was a tracked machine with wooden treads, affectionately known as a 'Marsh Molly’ .The Marsh Molly pushed a wedge-shaped V-plow down the ditch. As the plow proceeded, it deposited materials to both sides of the ditch to be compacted under Marsh Molly's wheels. Over time, the mechanized repeated ditching created dense maintenance embankments along both sides of the ditch.
From circa 1960s to the present, Open Marsh Water Management (OMWM) slowly began to replace ditch maintenance as an efficient way to reduce mosquito populations. To facilitate biological controls of mosquitoes, OMWM carefully applies marsh hydrology, tailored to each site. By creating a series of shallow ditches radiating out from a salt marsh pool into nearby mosquito breeding habitat, OMWM systems provide predatory fish access to previously unavailable mosquito breeding areas where they feed on the high concentrations of mosquito larvae.
Understanding the land use history of our New England salt marshes (pre-Columbian, colonial, and modern) and how marshes responded to the many alterations is critical to current and future restoration and management. Such knowledge offers resource managers an understanding of salt marshes' vital role in maintaining biodiversity and insight into marsh resiliency. We can learn how, after a disturbance, salt marshes and other habitats naturally undergo recovery, collectively referred to as secondary succession – how each step in the progression displays specific hydrology, plant community characteristics, and ecological function. The 350-year tradition of managing salt marshes by maintaining ditches is now thought to have interrupted secondary successional patterns and the natural potential to restore marsh equilibrium (6).
Understanding these patterns allows resource managers to identify and implement appropriate restorative measures. Refining and building this knowledge base now allows future resource managers to ensure our salt marshes adapt to sea level rise and other challenges of climate change, so they can continue to support coastal fisheries, protect our coasts from storms, help mitigate climate change by storing carbon, and inspire us with their beauty.
1. Clift, W. 1862. Salt Marshes. The mode of reclaiming them and their value. In Report of the Commissioner of Patents for the Year 1861. 343-358. Washington: Government Printing Office.
2. Sebold, K. R. (1992). From Marsh to Farm: The Landscape Transformation of Coastal New Jersey. Historic American Buildings Survey/Historic American Engineering Record, National Park Service, US Department of the Interior.
3. Hawes, E. 1986. Land reclamation in the New England salt marsh. In: Proceedings of the Dublin Seminar for New England Folklife. Boston: Boston University.
4. American Farmer. 1820. The draining of marshes. American Farmer: 243–245
5. Fessenden, T. G. 1823. On Embankments, Dikes, Drains, etc., for the Purpose of reclaiming lands from the sea, rivers, etc. In Fessenden, T.G., Ed. The New England Farmer. Vol 1(31), pp 241-243. Boston: Thomas W. Shepard, 1822-1835. https://www.biodiversitylibrary.org/page/24087040
6. Mora, J. W., & Burdick, D. M. (2013). The impact of man-made earthen barriers on the physical structure of New England tidal marshes (USA). Wetlands ecology and management, 21(6), 387-398.
Geoff is a forester with a focus on natural resource and recreation management. As the founder of a design/build consulting firm, Northeast Wetland Restoration established in 1989, Wilson has more than 30-years of experience restoring sensitive ecosystems from Maine south to Virginia, and west to Michigan’s Upper Peninsula. Since 1993, Wilson has held a position on the senior design team and as a co-manager of the Bear Creek Wildlife Sanctuary in Saugus, Massachusetts, a 370-acre urban migratory wildlife sanctuary integrated into an active landfill setting that serves as a nationally recognized sustainable living model for urban environments. Currently Wilson is a member of the Salt Marsh Adaptation and Resiliency Teams’ Design Review (SMARTeams’ DR) helping to develop nature-based design solutions that restore coastal resiliency and tidal marsh dependent species’ habitats in coastal marshes from northern Maine to Long Island.
Susan has a doctorate in Biological Oceanography and has been working at the Rachel Carson NWR for over 18 years with over 30 years experience in salt marsh ecology, restoration and estuarine science. Projects at Rachel Carson NWR have focused on developing innovative restoration techniques and coordinating the region-wide Salt Marsh Integrity Assessment.