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Green Infrastructure Network Mapping<\/span><\/span><\/p> Natural areas and gaps between, within, and adjacent to them have been mapped into a Countywide green infrastructure network. Natural Areas include streams, forests, wetlands, and non-forest habitat within the mapped network. These areas form the existing green infrastructure network elements that have the potential to be further connected, enhanced, conserved, restored, and protected.<\/span><\/p> The map uses four general network categories: <\/span><\/p> \u201cRegulated\u201d Areas <\/span><\/span><\/p><\/li> Other Protected Lands <\/span><\/span><\/p><\/li> Evaluation Areas <\/span><\/span><\/p><\/li> Network Gaps <\/span><\/p><\/li><\/ul> Based on whether the land cover within \u201cRegulated Areas and Other Protected Lands is natural areas, or gaps within, between, or adjacent to natural areas, the network is classified into a total of six mapping categories:<\/span><\/p> Natural Areas in \u201cRegulated\u201d Areas<\/span><\/span><\/p><\/li> Network Gaps in \u201cRegulated\u201d Areas<\/span><\/span><\/p><\/li> Natural Areas in Other Protected Lands<\/span><\/span><\/p><\/li> Network Gaps in Other Protected Lands<\/span><\/span><\/p><\/li> Evaluation Areas<\/span><\/span><\/p><\/li> Other Network Gaps<\/span><\/p><\/li><\/ul> The four general green infrastructure network categories and the six mapping categories are described below. <\/span><\/p> \u201cRegulated\u201d Areas<\/span><\/p> \u201cRegulated\u201d<\/span>Areas include environmentally sensitive features and their buffers such as streams, wetlands (where mapped in GIS), and 100-year floodplains, that are protected during the land development process by laws, guidelines, or regulations, and meet minimum criteria for inclusion in the netw<\/span><\/span>ork. \u201cRegulated\u201d<\/span><\/span>Areas are the areas along stream corridors (based on GIS data) that have a minimum width of existing forest, non-forest habitat managed by the Department of Parks, or unmanaged non-forest habitat discernable on aerial photographs, on both<\/span><\/span>sides of the stream. \u201cRegulated\u201d<\/span><\/span>Areas also include stream segments that do not meet the minimum natural area buffer coverage criteria, but provide potential linkages between stream segments that do meet the minimum criteria, or between other significant natural resources. <\/span><\/span>In \u201cRegulated\u201d<\/span><\/span>Areas, preservation is the main focus and development is not generally permitted except for necessary construction of road crossings and installation of public utilities. <\/span><\/p> <\/p> Quotation marks in the \u201cRegulated\u201d<\/span><\/span>Area category designation are used to indicate that these areas are only rough approximations of the areas that are regulated in the development review process. One reason for this is that the network map was based on County-scale GIS data, which are less accurate than site-specific data. Another reason is that other natural features that are used in determining regulated areas, such as steep slopes or erodible soils, need to be determined using field-verified data, and are not factored into the Countywide map. In <\/span><\/span>addition, because \u201cRegulated\u201d<\/span><\/span>Areas incorporate only those areas that meet the minimum criteria for inclusion within the green infrastructure network, the network map includes most, but not all, of the natural areas in the County that may be regulated. As a result, the Green Infrastructure Network Map is not a substitute for site-specific evaluations of natural resources<\/span><\/span>,<\/span><\/span>including those required for development review, but should always be used together with field-verified data. <\/span><\/p> <\/span><\/p> \u201cRegulated\u201d Areas are mapped using two sub-categories:<\/span><\/p> Natural Areas in \u201cRegulated\u201d<\/span><\/span>Areas<\/span><\/span><\/p> - Streams, forests, wetlands, and non-forest habitats within \u201cRegulated\u201d<\/span><\/span>Areas<\/span><\/p> Network Gaps in \u201cRegulated\u201d<\/span><\/span>Areas<\/span><\/span>(Described below under <\/span><\/span>Network Gaps<\/span><\/span>)<\/span><\/span><\/p> - Discontinuities between Natural A<\/span><\/span>reas in \u201cRegulated\u201d<\/span><\/span>Areas<\/span><\/span><\/p> <\/p><\/li><\/ul> <\/p> \"Regulated\u201d Area Mapping Criteria<\/span><\/p> <\/p> Green Infrastructure Network Analysis Areas<\/span><\/span><\/p> In setting the mapping criteria for \u201cRegulated\u201d Areas within the network the County was divided into three Green Infrastructure Mapping Analysis Areas based on comparative density of development: The Urban Ring (as defined in the General Plan), The Primary Funding Area (PFA) outside of the Urban Ring, and Outside of the PFA. Development density generally increases (and the mapping criteria for \u201cRegulated\u201d Area more inclusive) as one moves from the area outside of the PFA, to the PFA outside of the Urban Ring, to the Urban Ring. Mapping criteria are more inclusive with increasing density because of the significant loss of stream corridors over time in urban areas, and the heightened importance of those that remain in these areas. <\/span><\/p> \u201cRegulated\u201d Area stream corridors in the network were mapped at 200 feet, 250 feet, or 300 feet in width depending on the State Water Use Class, per the County\u2019s current Environmental Guidelines for Development (Maryland-National Capital Park and Planning Commission, 1997). As described above, the \u201cRegulated\u201d Area corridor widths were also expanded to include the 100-year floodplain, and GIS-mapped wetlands and ponds and their buffers that are within, or contiguous with, the \u201cRegulated\u201d Area corridors. Until a revised version of the Environmental Guidelines for Development is promulgated, the approximate buffers for streams within the Ten Mile Creek watershed will be shown per the current Environmental Guidelines. <\/span><\/p> <\/p> Criteria for Corridor Inclusion in the Network<\/span><\/p> <\/p> Outside of the Primary Funding Area:<\/span><\/span><\/p> Minimum 200-foot wide stream corridors that are covered by forest, non-forest habitat buffer managed by the Parks Department, or unmanaged non-forest habitat discernable by aerial photographs<\/span><\/span><\/p><\/li> Stream segments that do not meet the minimum criteria for natural area buffer coverage, but provide potential linkages between stream segments that do meet the minimum criteria, or other significant natural resources <\/span><\/p><\/li> <\/p><\/li><\/ul> Priority Funding Areas outside of the Urban Ring:<\/span><\/span><\/p> Minimum 100-foot wide stream corridors that are covered by forest, non-forest habitat buffer managed by the Parks Department, or unmanaged non-forest habitat discernable by aerial photographs<\/span><\/span><\/p><\/li> Stream segments that do not meet the minimum criteria for natural area buffer coverage, but provide potential linkages between stream segments that do meet the minimum criteria, or other significant natural resources<\/span><\/p><\/li> <\/p><\/li><\/ul> Urban Ring:<\/span><\/span><\/p> No minimum width criterion for stream corridor existing habitat buffer coverage <\/span><\/span><\/p><\/li><\/ul> <\/p> <\/p> Other Protected Lands<\/span><\/p> <\/p> Other Protected Lands includes existing lands that are protected primarily for their natural value by Local, State, and Federal government. These areas include:<\/span><\/p> <\/p> Existing M-NCPPC Parkland of the following types:<\/span><\/span><\/p> Best Natural Areas,<\/span><\/span><\/p><\/li> Biodiversity Areas,<\/span><\/span><\/p><\/li> Stream Valley Parks,<\/span><\/span><\/p><\/li> Conservation Parks,<\/span><\/span><\/p><\/li> Neighborhood Conservation Parks, and <\/span><\/p><\/li> Managed Open Natural Areas within these Parks, such as meadows<\/span><\/p><\/li> <\/p><\/li><\/ol><\/li><\/ol> All of the above parklands were included in the network except for several Neighborhood Conservation Parks that are very small and located more than 600 feet* from the network. <\/span><\/p> <\/p> Existing Federal and State Parks<\/span><\/p> Although some of the parks listed above have some non-natural areas within them such as agricultural land and park facilities, they are mostly natural lands. These areas will continue to be maintained and managed, by the respective government landowners as parklands that are recognized for the importance of the values and functions of their natural areas.<\/span><\/p> Category 1 Forest Conservation Easements including:<\/span><\/span><\/p> Category 1<\/span><\/span><\/p><\/li> Offsite (Category 1)<\/span><\/span><\/p><\/li><\/ol> Bank (Category 1)<\/span><\/span><\/p> Category 1 Forest Conservation Easements 5 acres and greater in size<\/span><\/span>1<\/span><\/span>and within 600 feet<\/span><\/span>2<\/span><\/span>of the network were included in the network by linking them with a network gap area. Some easements smaller than 5 acres, however, when located closer to the network, were also included in the network.<\/span><\/span><\/p> <\/li> Washington Suburban Sanitary Commission (WSSC) Lands (source water protection)<\/span><\/p><\/li><\/ol> These are lands owned and managed by WSSC as natural areas (predominantly forested) that provide protection for drinking source waters.<\/span><\/p> 1<\/span><\/span>The 5-acre criterion is based on guidance from the Audubon Society regarding minimum habitat area needed to support key migratory bird species (Audubon New York).<\/span><\/p> 2<\/span><\/span>The 600-foot distance criterion is based on published data and is the distance beyond which forest birds typically tend not to fly across gaps between forested areas (St. Clair, Belisle, Desrochers and Hannon, 1998; Harris and Reed, 2002)<\/span><\/span>.<\/span><\/span><\/p> <\/p> Other Protected Lands are mapped using two sub-categories:<\/span><\/p> <\/p> Natural Areas in Other Protected Lands<\/span><\/span><\/p> Streams, forests, wetlands, and non-forest habitats within Other Protected Lands<\/span><\/p> <\/p> Network Gaps in Other Protected Lands<\/span><\/span>(Described below under <\/span><\/span>