Forestry and Natural Resources Plan Glossary

Biophilia
The innate connection humans have to the natural world.  

Biophilic Community
A place that cherishes natural features that already exist and works to restore and repair what has been lost or degraded. A place that emulates nature by incorporating natural forms into its cityscape and buildings, and plans and designs in conjunction with nature.   

Champion Tree
Individual specimens of trees or shrubs that have been nominated and designated as the largest of that species in Arlington County.  

Casual Use Space
Space that supports casual, impromptu use, including relaxation, reflection, informal activities or connection with nature. May be publicly available at all times or at designated times.  

Conservation Easement
A voluntary legal agreement made between a private land owner and a land trust that allows land to continue to be privately owned but restricted to serve and protect the land for the public good.  

Cultivar
Also known as a “cultivated variety”, the term cultivar refers to a variety of plants purposely developed by horticulturists to favor selected traits such as height, flower or leaf color, or resistance to disease. Cultivars are often certified by name, and routinely propagated as clones to maintain genetic consistency.  

Ecotype
A population of (plant) species that has adapted to a particular set of environmental conditions through natural selection. Generally used to define a local population within a limited geographical range, i.e. local.  

Green Space
A land use planning and conservation term used to describe protected areas of undeveloped landscapes; sometimes used inter-changeably with ‘natural areas’. 

Green Street
A tree-lined street that is designed to serve as an extension of the public space system. Offers pedestrians, cyclists and drivers a more attractive travel experience, provides shade in the heat, blocks wind in the cold and may integrate stormwater management features.  

Impervious Land Cover
The area that does not allow rainfall to infiltrate the soil and typically includes buildings, parking lots, and roads.  

Invasive Plant Species
Sometimes referred to as “invasives” are defined as established and reproducing non-native plants, that through a combination of traits (aggressive growth, propensity to spread, immunity to native diseases, insects or herbivores), threaten the elimination of desired native species through competition and replacement . 

Land Cover 
Physical features on the earth mapped from satellite or aerial imagery such as bare soils, canopy, impervious, pervious, or water. 

Nativar
A cultivated variety of a native plant

Native Plant Communities
A vegetation classification unit defined on the basis of a characteristic range of species composition, diagnostic species occurrence, habitat conditions, and physiognomy.  The Virginia Natural Heritage Program (VNHP) currently lists over 120 natural plant communities as occurring within Virginia.  

Native Plant Species
Those plant species (trees, shrubs, ferns, forbs, grasses and sedges) documented to be growing naturally within the boundaries of Arlington County and reasonably assumed to have had an historical presence before the arrival of Europeans. These species are not known to have been introduced to the area, nor have escaped from cultivation.  

Natural Area
In Arlington County, documented natural lands occur primarily as variations   mid-late successional hardwood forest aging from 85-200 years old, generally exhibiting historically undisturbed soils and displaying a complete and diverse native vegetation structure (canopy, sub-canopy, shrub and herb layer). Some of the most recognizable examples include meadows, forests/woods, or streams.

Natural Lands
In Arlington County, documented natural lands occur primarily as variations of mid-late successional hardwood forest aging from 85-200 years old, generally exhibiting historically undisturbed soils and displaying a complete and diverse native vegetation structure (canopy, sub-canopy, shrub and herb layer). Few non-forested natural lands remain in Arlington, but would include several documented remnant woodland meadows (glens), bogs, seeps, and tidal marsh. 

Natural Resources
Living organisms and non-living materials that humans and other life forms depend on, and that are derived from or are part of the environment, including water, soils, minerals, air, vegetation, fauna, fungi, etc.  

Natural Surface Trail
Located primarily along streams, stream valleys and in other natural areas, natural trails are unpaved paths used primarily by pedestrians and hikers.  

Non-Native Plant Species
The opposite of locally native plant species. Native to a geographic location other than Arlington County, and if present currently, is the result of intentional or accidental introduction or escape from cultivation, including hybrids, plants that result from genetic engineering or horticultural cultivars. 

Open Water Land Cover
The land cover areas mapped as water typically include lakes, oceans, rivers, and streams.  

Pervious Land Cover
The vegetative area that allows rainfall to infiltrate the soil and typically includes parks, golf courses, and residential areas.  

Possible UTC
The amount of land that is theoretically available for the establishment of tree canopy within the county boundary. This includes all pervious and bare soil surfaces.  

Potential UTC
This is the sum of existing urban tree canopy and the preferred plantable area. 

Privately-owned Public Space
A privately developed space that remains under private ownership but has an easement or license that guarantees it is open and accessible to the public.  

Preferred Plantable Area
The amount of land that is realistically available for the establishment of tree canopy within the county boundary. This includes all pervious and bare soil surfaces with specified land uses. 

Stream Corridor
A complex ecosystem around streams which includes the land, plants, animals, and network of streams within it. 

Streetscape
The urban element that establishes a major part of the public realm. The streetscape is composed of thoroughfares (travel lanes for vehicles and bicycles, parking lanes for cars), public frontage (sidewalks, shy zones) as well as the visible private frontages (building facades and elevations, yards, fences, awnings, etc.) and, importantly the amenities of the public frontages (street trees and plantings, benches, streetlights, etc.). 

Tree Canopy
Branches and foliage which make up a tree’s crown.  

Tree Canopy Cover
As seen from above, it is the area of land surface that is covered by tree canopy.  

Tree Canopy Spread
The width of a tree’s canopy, usually measured in five-foot increments.  

Tree Canopy Land Cover
The area of land surface that is covered by the tree’s leaf covered branches as seen from above the ground surface.  

Urban Forest
All of the trees within a municipality or a community. This can include the trees along streets or rights-of-way, parks and greenspaces, and forests.  

Urban Tree Canopy Assessment (UTC)
A study performed on land cover classes to gain an understanding of the tree canopy coverage, particularly as it relates to the amount of tree canopy that currently exists and the amount of tree canopy that could exist. Typically performed using aerial photographs, GIS data, or LIDAR.