Maryland's Habitat Connectivity Network Introduction
Maryland’s Habitat Connectivity Network (HCN) is our natural support system, providing ecosystem services that are necessary to humans, as well as plants and animals. As Maryland’s population increases, natural areas are being lost to development. Prior to European settlement, about 95% of Maryland’s six million acres of land was covered in forest. Today, forest cover is around 40%. In Maryland’s early post-colonial history, forest loss was due to agricultural conversion. In the early part of the 20th century, many marginal farms were abandoned and reverted back to forest. However, in the last half of the 20th century, urban development replaced an estimated 7,200 acres of forest land per year.
The scattered pattern of modern development not only consumes an extensive amount of land, it fragments the landscape, converting a once near-continuous stretch of forests and wetlands to small, isolated islands of habitat in a sea of developed land. Since a statewide comprehensive approach to address landscape fragmentation did not exist, Maryland’s Department of Natural Resources (DNR) began an effort in the late 1990’s to identify the most ecologically important lands in the State. The result of this effort is a mapped network of large blocks of intact forest and wetlands, called “hubs,” linked together by linear features such as forested stream valleys, ridgelines, or other natural areas, called “corridors.” An essential characteristic of the habitat connectivity network is the interconnection of its features.
2024 Update of the Habitat Connectivity Network
Maryland’s Habitat Connectivity Network, (previously known as Green Infrastructure), was first produced in 2005, with updates to hub areas in 2011. The 2024 update leverages the Chesapeake Bay Program's cutting-edge, high-resolution 2017/2018 land use/land cover mapping and provides several additional enhancements, including differentiation of hub and corridor types (forest, wetland, or aquatic), a breakdown of land cover types within corridors, and identification of potentially restorable gaps within corridors. The updated Habitat Connectivity Network map layer can be viewed on the Maryland GreenPrint web map (
https://mdgeodata.md.gov/greenprint/ ). The data layer can be downloaded from the Maryland iMap Data Catalog . An archived version of the original Green Infrastructure data can be accessed
here.
The HCN provides essential information for environmental planning to support Maryland DNR and its private and public partners
Other Natural Area Data Sets
In addition to the Habitat Connectivity Network, the DNR had developed three other statewide databases based upon extensive scientific work. Like the Habitat Connectivity Network, each database identifies ecological attributes of land throughout the state:
- The Rare Species Habitat database includes additional habitats that support rare, threatened and endangered species.
- The Aquatic Life Hotspots database adds watershed land and streams that support areas of high aquatic biodiversity.
- The Water Quality Protection database focuses on those watershed lands, such as forests, wetlands and steep slopes that are most important for improving water quality services.
How the Habitat Connectivity Network is Being Used
Like the Green Infrastructure before it, the Habitat Connectivity Network is now incorporated as one of the factors used to evaluate potential acquisitions through DNR’s land conservation programs.
