Vulnerability Assessment

Threats to the sustainability of forestlands arise from multiple potential stressors. The most obvious threat is the conversion of forestland into some form of urban use – residential, commercial, industrial or institutional – with consequent loss of most of its natural resource values. The Maryland Department of Planning estimates 10,000 acres of forest land are lost each year to development. Maryland’s forest resources are also threatened by other forces, including biological pests (exotic species, overabundant deer, etc.) as well as abiotic factors (e.g. - fire, acid deposition). For purposes of the Strategic Forest Lands Assessment, the vulnerability model that has been developed focuses on the threat of conversion of forestland to development. It does not (directly) incorporate other biotic and abiotic stressors.

The model looks at regional and site specific factors that contribute to the vulnerability of a given acre of forest to development as well as factors that make its conversion less likely. Examples of site specific data layers used to determine how vulnerable an area is include:

• the current level of protection arising from public ownership, conservation or agricultural easements
• constraints on development as a result of physical limitations or regulations associated with environmentally sensitive features, including wetlands and riparian areas, steep slopes, and sensitive habitats.

The vulnerability of forest land to development is also heavily influenced by the geographic setting. Market forces can drive the long term sustainability of forests as a preferred land use. The vulnerability model approximates these effects by including data layers to assess:

• proximity to population centers
• road access and density
• proximity to existing protected open space
• real estate values

Finally, public policy and investment can also be used to direct growth and, correspondingly, the conservation of forest resources. The model addresses these factors by including data layers for:

• existing water and sewer service areas
• Priority Funding Areas
• local zoning
• Chesapeake Bay Critical Area

Data sets and indicators used to develop the vulnerability ranking of the SFLA include:

• Population density
• Generalized zoning of forest lands
• Protection status of forested lands
• Wildfire