Delaware, once mostly forested, has lost over half of its forests since the time of European settlement. Historically, losses stemmed from conversion to agriculture, but now they are mostly the result of residential and commercial development and associated infrastructure. Forest loss stabilized around 1900, and Delaware’s forestlands have increased in the early 20th century, but these recovered forestlands lack the species diversity that once existed prior to European settlement. Today, residential and commercial development has resulted in a loss of forestland and forest acreage.   

Delaware Forest Acres

In total, one-third of Delaware’s forests, are protected from development. These lands include government-owned and NGO tracts, as well as areas protected by permanent conservation easements, including over 36,000 acres of forestland protected through easements purchased by the Delaware Aglands and Forestland Preservation Program (Delaware Forest Service 2020).   

The Great Cypress Swamp, a large, forested wetland complex spanning the border of Sussex County, Delaware and Worcester County Maryland once covered nearly 50,000 acres with forests dominated by Atlantic white cedar and bald cypress. Since the early 1800s, however, logging, ditching, draining, drought, and fire have reduced the swamp to a quarter of its pre-colonial size, and have resulted in major shifts in the dominant vegetation comprising the forests. Despite drastic changes in the swamp over the last 200 years, it is currently one of the largest contiguous tracts of forest remaining on the Delmarva Peninsula (Bennett et al. 1999). 

Delaware Forest Service manages three state forests totaling over 20,000 acres: Blackbird State Forest (6,000 acres) near Smyrna, Taber State Forest (1,309 acres) near Harrington, and Redden State Forest (over 14,000 acres) near Georgetown. 

Delaware’s forested habitats are highly fragmented. Mapping of tree cover in the state completed in 2004 by DNREC’s Division of Parks and Recreation delineated about 4,150 separate wooded patches larger than 10 acres (DNREC unpublished data). The median size among those patches is only 34 acres, and just 6% are larger than 250 acres. An examination of patch “thickness,” which accounts for size and shape, revealed that only a few (<0.1%) patches had sufficient interior habitat to sustain area-sensitive forest species. Additional analysis indicates that the patches are highly isolated from each other, with less than 10% meeting the isolation thresholds for hooded warbler, American redstart, red-shouldered hawk, and brown creeper. Finally, calculation of perimeter/area ratio for the forest blocks highlights their very irregular shapes. Almost 90% have a ratio greater than that of a 10:1 rectangle, a configuration that produces major edge effects. 

Field surveys of nearly 100 Coastal Plain forest blocks found about half of them to be in “Good” or “Very Good” condition, but this rating was based on vegetative characteristics, not on spatial attributes or wildlife habitat (McAvoy et al. 2006). 

In Delaware and throughout the region fire suppression has led to “mesophication” of forest, a shift from fire-adapted, shade-intolerant species to fire-sensitive, shade-tolerant species (Nowacki and Abrams 2008).  

In addition, the gypsy moth, which was first detected in Delaware in 1979, severely impacted oak forests throughout the state. Many of these forests now lack sufficient canopy tree regeneration potential or have experienced mesophication because of changes in species composition from oak to maple and gum (Delaware Forest Service 2020).  

Fire suppression, mesophication, invasive plant species, and overbrowsing by White-tailed Deer have severely reduced the ability of northeastern forests to regenerate. 

More information about Delaware’s Forests can be found in the Delaware Forest Resource Assessment and the Statewide Forest Strategy, produced by the Delaware Department of Agriculture’s Delaware Forest Service, and updated and submitted to the U.S. Forest Service every ten years. 

These coastal upland habitats are adapted to the dynamic conditions of shifting sands, strong winds, and salt spray unique to the narrow zone along the Atlantic Ocean and Delaware Bay. They range from sandy beach above the high-tide line to the grassy dunes and overwashes, to a complex of shrub-dominated back dunes. Intertidal beach areas are covered under the Tidal Wetlands section, while groundwater-controlled interdunal wetlands or swales are included in Non-tidal Wetlands. 

These habitats have declined significantly in extent and quality during historical times, primarily because of residential development and associated infrastructure, particularly artificial shoreline hardening and jetties and groins. In recent decades, this decline has greatly slowed on the Atlantic Coast, where most remaining habitats are on public land. Losses continue, albeit more slowly, along the shorelines of the Delaware Bay and Inland Bays. All these habitats are subjected to on-going impacts from recreational activities, and Delaware Bay beaches in particular are occasionally impacted by oil spills. The long-term prospect for beaches and dunes is potentially poor given predicted sea level rise, even though these disturbance-dependent habitats might be expected to accommodate sea level rise reasonably well by migrating inland. However, onshore and offshore coastal processes that would facilitate such a shift, especially sand transport, may have already been irreversibly compromised by the issues noted above. Efforts to stabilize dunes may also further disrupt these processes in the future, despite their seeming benefits at present. Beach replenishment is a potential solution to the loss of natural sand transport, but costs are very high and nearshore habitats that serve as a sand source, as well as intertidal habitats upon which sand is placed, may be adversely impacted. 

Delaware has a rich history of agriculture, and this land use has heavily shaped the distribution, structure, and quality of habitats in the state. Thirty-nine percent of all land in Delaware is part of a farm (Kee n.d.). As in other states, many forests and early successional habitats were previously farmed, wetlands ditched, and marshes managed for salt hay. Today’s agricultural landscape in Delaware is dominated by row crops. The upland areas of the Coastal Plain host the most intensive row crop agriculture on the Delmarva Peninsula, including primarily corn and soybeans. In addition, poultry farms are widespread and are highly economically important. Vegetable production accounts for fewer acres, but is nearly as valuable as corn and soybeans in terms of annual commodity marketing receipts (Kee n.d.). Statewide, land in farms decreased from 589,107 acres in 1997 to 520,000 acres in 2024. Total cropland as of 2025 was 414,800 acres, with a total of 403,700 acres harvested.  

Loss of habitat heterogeneity is a major factor driving observed declines in farmland biodiversity around the world, and farms with greater on-farm heterogeneity support higher levels of biodiversity (Belfrage et al. 2015). Throughout the country, the removal of fencerows and enlargement of fields that has accompanied agricultural intensification during the second half of the 20^th century has led to decreased structural heterogeneity on working farms (Best 1983, Basore et al 1986). 

Opportunities for conservation on working lands are provided by several USDA Natural Resources Conservation Service (NRCS) programs, including the Conservation Reserve Program (CRP), Wetlands Reserve Program (WRP), Farmable Wetlands Program (FWP), and Conservation Reserve Enhancement Program (CREP). CRP is a program established by the USDA in 1985 that takes land prone to erosion out of production for 10 to 15 years and devotes it to conservation uses. In return, farmers receive an annual rental payment for carrying out approved conservation practices on the conservation acreage. The WRP, FWP, and CREP programs are included under the Conservation Reserve Program and offer landowners financial incentives for conservation practices such as filter strips. Acres in these programs declined from 9,221 in 2007 to 7,808 in 2012, and only 2,837 in 2025 (USDA 2025).

Non-tidal freshwater wetlands are the most abundant wetland type by acreage in Delaware, at just over 166,597 acres mapped (DNREC 2022). These wetlands support a large percentage of the biological diversity and rare species found in Delaware. Though sea level rise is not as great a threat to non-tidal wetlands as tidal wetlands, loss of these habitats has already occurred, and is one of the causes of the loss of 2,773 acres of nontidal wetland between 2007 and 2017. Conversion of non-tidal wetlands to tidal, and further wetland loss, is predicted to continue as sea level rises. 

A variety of human-modified wetland habitats occur in Delaware. While these habitats may not serve the same ecological functions as natural wetlands, they are nevertheless important to various SGCN. Because these modified lentic water bodies serve as “catch basins” for pollutants, nutrients, and sediments from the surrounding area, they are especially susceptible to water quality impairment. DNREC has found that 74% of Delaware’s freshwater ponds and lakes do not fully support the fish and wildlife designated use as defined by water quality criteria (DNREC 2013). 

With over 113,000 acres of tidal estuarine wetlands and over 10,000 acres of tidal palustrine wetlands, Delaware’s tidal wetlands in total account for nearly half of the state’s wetlands (DNREC 2022). Tidal marshes are widely recognized for their ecological importance, as well as their importance to human populations. Tidal marshes filter contaminants and nutrients, improve water quality, sequester carbon, and protect coastal communities from flooding (Kreeger et al. 2010). A wide range of terrestrial and aquatic species, including birds and commercial and recreational fish and crustacean species, use tidal marsh habitats for nursery grounds and other functions during their life cycles. 

The Delaware River is fringed by a contiguous band of brackish/saltwater tidal marshes from the mouth of Delaware Bay upstream to the Delaware Memorial Bridge. Beyond the tidal marsh fringe, tidal wetlands are predominately tributary-associated freshwater tidal wetlands that occur in discrete patches. 

Salinities in polyhaline salt marshes near the mouth of the Delaware Bay range from 18 to 30 parts per thousand (ppt) and are dominated by two grass species, Smooth Cordgrass (Spartina alterniflora) and Saltmeadow Cordgrass (Spartina patens). Brackish (mesohaline) marshes, with higher vascular plant diversity than salt marshes, occur upstream of the bay mouth in salinity ranges from 5 to 18 ppt (Odum 1988). Oligohaline marshes with salinities less than 5 ppt support the highest species diversity and are at most risk from sea level rise. These habitats provide a critical buffer between the tidal ocean and bay aquatic environments and the upland habitats of the Delaware Estuary. 

It has been estimated that the Delaware Estuary has lost more than half of its wetlands, and more than 95% of freshwater tidal wetlands, since early settlers arrived (PDE 2008). Historical losses occurred primarily because of development and conversion of wetlands for agriculture and other purposes. Despite increased regulatory oversight and “no net loss” policies that have greatly slowed rates of wetland conversion, we continue to lose all types of wetlands within the Delaware River Basin (PDE 2012).

Although seldom destroyed outright, these habitats have been somewhat impacted by ditching, dredging, and channelization. They also have long been subject to incremental degradation arising from incompatible land use practices upslope, often magnified by the frequent loss of adjacent buffers. Opportunities for migration inland of this habitat in the face of sea level rise will be limited by topographic features and mill pond dams on tidal coastal plain streams. Purely fresh (0 ppt) tidal marshes in Delaware are now only found on the Christina and Nanticoke Rivers (W. McAvoy personal communication). It is estimated that between 84% and 98% of freshwater tidal wetlands will be impacted by sea level rise by 2100 (Love et al. 2012). 

Estuarine wetlands are systems associated with coastal salt or brackish waters. These areas extend upstream into coastal rivers to the point where salinity levels decline to negligible levels (less than 0.5 ppt).  

Eighty-one percent of Delaware’s estuarine wetlands occur on fringe landforms, with unobstructed connection to tidal embayments. Islands of wetland surrounded by open water account for 12%, while 7% of estuarine wetlands in Delaware are cut off from full tidal flow by roads, dikes, or similar structures and are thus considered basin landform types. These were discussed above under impoundments. 

The predominant estuarine habitat in Delaware is salt marsh. Delaware has high regional responsibility for salt marsh habitat, with 9% of the salt marsh in the Northeast region (Anderson et al. 2013a), relative to only about 1% of the land area.

Salt marshes are universally considered to be among the most important wildlife habitats in North America, and Delaware’s contribution to the regional distribution and conservation of this habitat is significant.

The Delaware Bay covers nearly one quarter the surface area of the state of Delaware. The Bay’s benthic habitats are highly diverse in their physical characteristics. They include shallow submerged mudflats, rippled sand flats, rocky hard-bottom habitats, silty and sandy shoals, shellfish beds, and tube worm reefs. 

Generally, nearshore habitat in the Delaware Estuary has experienced an improvement since the 1930s and 1940s when pollution blocks degraded habitat, particularly in the upper estuary.

Sediment grain size in the Delaware Estuary varies across a wide range, from gravel to clay. The grain size of sediments is an important ecological indicator and one of the primary factors influencing the distribution of various benthic organisms and ecological communities.  

In 2014, DNREC’s Delaware Coastal Programs completed work on an acoustic mapping project of the benthic sediments in the Delaware portion of the Bay and the nearshore Atlantic marine areas. This project classified substrates into one of four categories: Sand and Muddy Sand, Mud and Sandy Mud, Coarse Sediments, and Mixed Sediments (Delaware Coastal Programs 2014). 

There is significant heterogeneity of sediment types and patchy distribution at many locations within the estuary, particularly in the reach from Wilmington to Liston Point. In this segment of the estuary, the dominant bottom sediment type is mud, whereas downstream of Liston Point the bottom is dominated by mixtures of sand and gravel with lesser amounts of mud. The zone of dominant muddy bottom corresponds to the estuary turbidity maximum (ETM), which results from the complex interaction of freshwater inflows from upstream sources with denser, more saline water from the Atlantic Ocean (Partnership for the Delaware Estuary 2012). 

As part of TNC’s NAMERA, a detailed map of benthic habitat types was created for the Delaware Bay and Atlantic Ocean. These habitat types, called Ecological Marine Units (EMUs), are the three-way combination of physical variables: depth, sediment grain size, and seabed forms. The breaks in bathymetry and substrate grain size are based on ecological thresholds revealed by the benthic organism relationships.

The substrate types used in this plan are adapted from those used by the Atlantic Coastal Fish Habitat Partnership (ACFHP); these also correspond to the CMECS Substrate Component.