Glossary for urban green infrastructure

Biodiversity: Biodiversity is the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems, and the ecological complexes of which they are part. It includes diversity within and between species, and between ecosystems (Source: Convention on Biological Diversity).

City*: Term used generically to denote any urban form but more often applied to large and densely populated urban settlements (Source: GOOD). In Europe, there are different accepted approaches to describing the boundaries of a city: (1) focused on social or cultural aspects (e.g. based on administrative units, population density), (2) focused on biophysical layout (e.g. land cover, contiguity of built-up areas), and (3) focused on functional aspects (e.g. labour market and commuting patterns). In order to capture the whole performance of interconnected urban GI elements, we have considered two complementary spatial delineations within a city: inside the city and the urban fringe.

Connectivity: Term to express how a landscape is configured and how it allows species to move through its different elements (Source: SWD/2013/0155 final). A high degree of connectivity is generally linked to low fragmentation.

Core city: This is one of two spatial delineations of cities (core city and functional urban area) defined by the Urban Audit project (Source: Eurostat – Urban Audit). The core city level is mainly defined by its administrative and/or political boundaries; therefore data are directly relevant to policy-makers. The core city is the administrative reference unit for many socio-economic indicators.

Counterurbanisation or de-urbanisation: The social and demographic process originated by the movement of people from cities to the countryside or rural areas, seeking a better quality of life (Source: Urban Geography Glossary). This is the inverse process of urbanisation.

Degree of urbanisation: The degree of urbanisation is a classification system described by Eurostat, which classifies local administrative units (at LAU2 level) as cities, towns and suburbs, or rural areas based on a combination of geographical contiguity and minimum population thresholds applied to 1 km² population grid cells (Source: Eurostat – Degree of urbanisation).

Ecological networks: Biotic interactions in an ecosystem in which species (nodes) are connected by pairwise interactions (links) (Source: SWD/2013/0155 final). They include areas covered by a wide range of conservation measures, from a single ecoduct to intercontinental connected networks of protected and non-protected areas. Each GI element should play a role in the ecological network.

Ecosystem: An ecosystem is a community of living organisms (biotic components) — plants, animals and microorganisms — and their physical environment (abiotic components) that interact as a functional unit (Source: SWD/2013/0155 final). Living and non-living components are non-separable factors, they form a functional unit; each organism interacts with other organisms and with the physical conditions that are present in their habitats. Ecosystems are often grouped in units that have similar specific biotic and abiotic features.

Ecosystem based approach: The ecosystem based approach is the combination of strategies and measures for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way (Source: Convention on Biological Diversity).

Ecosystem services: Benefits that people obtain from ecosystems or their direct and indirect contributions to human well-being (Source: SWD/2013/0155 final). These include supporting services such as nutrient cycling; provisioning services such as supply of food and water; regulating services such as flood regulation and disease control; cultural services such as spiritual, recreational, cultural and aesthetic benefits.

Landscape fragmentation: The breaking-up of continuous landscape features into isolated or semi-isolated patches (Source: EEA multilingual environmental glossary). Fragmentation creates barriers to migration or the dispersal of organisms and reduces the size of extensive ecosystems. Fragmentation may be induced by human activities (e.g. road infrastructures, dams) or by natural processes.

Functional Urban Area (FUA): This is one of the two spatial delineations of cities defined by the Urban Audit project, which consists of the combination of a city plus its commuting zone (Source: EU-OECD FUA). City administrative boundaries do not act as barriers between people living inside and outside the city. Therefore, a second definition level, which is complementary to the core city, was described. The FUA captures how far the functional influences of a city go beyond its immediate administrative boundaries (Source: Eurostat – Statistics Explained). This was formerly known as a Larger Urban Zone (LUZ).

Green Infrastructure (GI): A strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services (as defined by the EC’s GI communication – COM/2013/0249final). GI is present in both rural and urban settings. In urban areas, many different features may be part of GI (e.g. parks, gardens, grassy verges, green walls or green roofs) as far as they are part of an interconnected network and are delivering multiple ecosystem services. These green urban elements (or blue if aquatic ecosystems are concerned) may be found within the city and in its peri-urban area.

Green Urban Area (GUA): A patch of vegetated land within the urban fabric for predominantly recreational use. GUA can also refer to suburban natural areas that are managed as urban parks (Source: adapted from Corine Land Cover classification). GUAs may include assets of different scales from green roofs or pocket gardens to large urban parks.

Green space: See Green Urban Area definition.

Imperviousness: Term referred to sealed soils that are characterised by artificial impenetrable surfaces. Imperviousness eliminates essential soil functions such as rainwater infiltration, natural groundwater recharge, food production, carbon storage or biodiversity shelter (Source: EEA Glossary).

Inner City: In this work, inner-city level considers all the elements contained within city boundaries, including both the city centre and its surrounding area.

Landscape: The traits, patterns and structure of a specific geographic area, including its biological composition, its physical environment and its anthropogenic or social patterns. An area where interacting ecosystems are grouped and repeated in a similar form (Source: EPAGLO).

Larger Urban Zone (LUZ): This definition has recently been replaced by the Functional Urban Area.

Land use: Land use describes the social and economic purposes for which land is managed (e.g. housing, intensive agriculture or transport). It comprises all the activities undertaken in a certain land-cover type (Source: GOOD).

Local Administrative Unit (LAU): LAUs form a system for dividing up the economic territory of the European Union (EU) for the purpose of local level statistics (Source: Eurostat – Statistics Explained). Generally, a LAU is a low level administrative division of a country, ranked below a province, region or state. In the European Union, LAUs are basic components of Nomenclature of Territorial Units for Statistics (NUTS) regions.

Natural capital: Natural capital is the extension of the economic notion of capital (manufactured means of production) to environmental goods and services (Source: SWD/2013/0155 final). Natural capital is the stock of natural ecosystems that yields a flow of valuable ecosystem goods or services into the future.

Nature-based solutions: Nature-based solutions are those actions that are inspired or supported by natural processes, which simultaneously provide environmental, social and economic benefits (Source: EC Research & Innovation – Policy topics). Such solutions are designed to bring natural features and processes to cities, landscapes and seascapes. They are often cost-effective approaches.

Peri-urban area**: See Urban fringe definition.

Planning: The interdisciplinary process of evaluating, organising, and controlling the present and future development, and use of land and its resources (Source: UNUN). It is a technical, political and participatory process regarding the use of land (e.g. housing, green areas), which includes an overall ecological evaluation in terms of specific uses as well as the evaluation of social, economic and physical contexts.

Suburbs**: See Urban fringe definition.

Suburbanisation: The process by which people, factories, offices and shops move out from the central areas of cities into the suburbs. This is often linked to increased business activities a decrease in the population in city centres. (Source: EC. 1999. Transport and the environment. A multi-country approach)

Urban area*:  See City definition.

Urban Audit: The Urban Audit project is a joint initiative of the European Commission and Eurostat (coordinator), which represents a response to the growing need for information about cities (Source: Eurostat – Statistics Explained). The main objective of the programme is for to participating European cities to provide objective and comparable statistics on a voluntary basis. 

Urban Fringe**: In this work, the urban fringe is considered as the area located on the periphery of a city. It represents the transition zone between the built-up area and the countryside, constituting the interface between the consolidated urban and rural regions. It is a zone of mixed land uses, where there is often competition for land use.

Urban Morphological Zone (UMZ): A set of urban areas lying less than 200 m apart and considered to contribute to the urban tissue and function (Source: EEA). UMZs are derived from CORINE Land Cover (CLC) by using urban core classes (residential, industrial and commercial, green urban areas) within a fixed distance (200 m) and adding enlarged core classes in case they fulfil certain neighbourhood conditions. UMZs better reflect the physical outline of cities, compared to administrative reference units.

Urban Sprawl: The unplanned and uncontrolled growth of urban areas into the surrounding countryside (Source: GOOD). Urban sprawl is the physical pattern of low-density expansion of large urban areas under market conditions into the surrounding agricultural areas. Development is patchy, scattered and strung out, with a tendency to discontinuity because it leap-frogs over some areas, leaving agricultural enclaves.

Urbanisation: Urbanisation is the increase in the proportion of people living in towns and cities (Source: Internet geography).

Vulnerability: Vulnerability is the degree to which a system is susceptible to and unable to cope with the adverse effects of injury, damage or harm (Source: IPPC. Methodological and Technological issues in technology transfer). This term normally  refers to climate change effects. In this sense, urban vulnerability depends on the character, magnitude, and rate of climate change events and, on the other hand, on the city’s sensitivity and adaptive capacity to them.

Notes

* In this work on green infrastructure (GI), no distinction is made between cities and urban areas.

** In this work on GI, synonyms such as peri-urban area and urban fringe are used.