Worldwide, the ways of considering ecosystems and their importance to human societies has undergone dramatic changes during recent decades. It has become increasingly clear that the goods and services provided to urban dwellers by various types of ecosystems are essential (). The recognition of this linkage between ecosystem services and human well-being leads to a strong case for them to be planned together. The Green Infrastructure (GI) approach appears to offer a way of combining and analysing this linkage. The authors’ aim for this paper is to describe a new framework for analysing, developing and delivering GI. This is achieved through addressing the following objectives: (1) discussing the concept of GI in both ecological and social terms; (2) describing a new conceptual framework of GI that could be applied at multiple spatial and temporal scales; (3) providing directions for future research, and for developing and delivering GI in the emerging context of ecosystem services and human well-being.
Introducing and defining Green Infrastructure
Benedict & McMahon () define Green Infrastructure (GI) as an interconnected network of green space that conserves natural ecosystem values and functions and provides associated benefits to human populations. Benedict and McMahon also contend that GI is the ecological framework needed for environmental, social and economic sustainability and that it differs from conventional approaches to open space planning because it looks at conservation values and actions in concert with land development, growth management and built infrastructure planning.
Weber et al. () describes Green Infrastructure as the abundance and distribution of natural features in the landscape which, in addition to supporting ecological processes, also contribute to human health and well-being (). Ewers et al. () and Lafortezza et al. () both recognise that Green Infrastructure is becoming a preminent approach for delivering essential goods and services to people whilst simultaneously reversing trends such as landscape and habitat fragmentation.
Taking a practitioner-led consultation approach, Davies et al. () identified a typology of multi-functional open spaces, including formal parks, gardens, woodlands, green corridors, waterways, street trees and open countryside, which when taken together comprised an “environmental resource”, which contributes towards sustainable resource management. Green Infrastructure is also presented as the integration and interaction of different services and benefits on the same area, notably through the use of the term “multi-functionality” used to describe the many functions delivered through appropriate management of the same piece of land (). This is seen as key to the efficient and sustainable use of land, especially in the compact and rapidly expanding European cities, where pressures on land are particularly acute (, ).
Ortega-Álvarez & MacGregor-Fors () present Green Infrastructure in structural terms as components that work together to maintain a network of sites supporting ecological and social processes. These components range in size and shape depending upon the type of function or service being provided. Generally, two main components are identified: hubs and links. Hubs act as “anchor” for a variety of ecosystem services, providing source and sink habitats for species dispersing through the landscape (). This component may include elements, such as reserves, parks and open spaces, residual lands, forests and farmlands. Links are the connections binding the ecosystems together, facilitating the flow of ecological processes; links may include, green corridors, green belts and stepping stones ().
The term GI is appearing more and more frequently in land and planning related topics across different regions, and at different levels, from the city to the supranational level (). However, the term means different things to different people, and can be described and assessed in many different ways (). The GI approach first reached Europe via the UK; Mell () contends that in the UK the focus is embedding it into different areas of planning policy.
The National Planning Policy Framework for England 2012 (Department of Communities and Local Government, UK) stipulates that “Local Plans should take account of climate change over the longer term, and that when new development is brought forward in areas which are vulnerable, care should be taken to ensure that risks can be managed through suitable adaptation measures, including through the planning of Green Infrastructure” ().
At a European scale GI has been defined as a “concept addressing the connectivity of ecosystems, their protection and the provision of ecosystem services, while also addressing mitigation and adaptation to climate change” (). The European Commission EU, DG Environment Biodiversity Unit () see the concept as “central to the overall objective of ecosystem restoration, which is now part of the European Union’s 2020 biodiversity target. It also promotes integrated spatial planning by identifying multifunctional zones and by incorporating habitat restoration measures and other connectivity elements into various land-use plans and policies, such as linking peri-urban and urban areas or in marine spatial planning policy”.
It is clear that those conceptualising Green Infrastructure including Benedict & McMahon (), Weber et al. (), Davies et al. () and Tzoulas et al. () all see the link between ecological and social factors as crucial to the Green Infrastructure approach, but this is not necessarily reflected in practice as illustrated by the review of examples examined in this research (Tab. S1 in Appendix 1). In these examples the predominant characteristic is spatially driven landscape management undertaken within the constraints of territorial planning and social and ecological outcomes are bi-products rather than co-products of the approach ().
The literature review does however indicate that there is relatively little consideration being given to temporal considerations. This suggests that there is insufficient recognition of the correlation between the delivery of land-use public policy and land management practice and the positive or negative impact of these on performance of Green Infrastructure through time ().
Green Infrastructure and Ecosystem Services
Ecosystems, through their normal functioning, provide a range of goods and services important for human well-being, which are collectively called ecosystem services (, , ). Ecosystem services, such as cleaning the air, filtering water, cycling nutrients, generating soils, regulating climate, sequestering carbon, etc. are all provided by forest areas, wetlands, and other natural ecosystems (, ). The concept of ecosystem services is regarded as encompassing a paradigm shift from pure ecosystem conservation to a focus on conserving ecosystem functionality ().
A recent report by Forest Research () provides an overview of the main ecosystem services that can be attributed to GI and their associated components using the classification created by the Millennium Ecosystem Assessment (). From the report, it is clear that GI may influence the capacity of ecosystem to provide services across a range of landscape scales (). For example, GI can mitigate risks from climate change by protecting urban regions against floods and other negative effects of changing weather patterns (, ).
One of the challenges to ecosystem functionality and the provision of ecosystem services is the increasing fragmentation of landscapes and ecosystems (). Mounting levels of urbanization and transport infrastructure have created a network of barriers that results in a patchwork of land uses and isolate open space areas. Consequently natural ecosystems have become scattered across the landscape and displaced by new land-use developments (, , ). According to the PLUREL project () more than a quarter of European landscapes are directly affected by urban land use; over the period 2000-2006, peri-urban (discontinuous) areas grew four times faster than continuous urban areas. The trend towards urban living is set to continue: by 2020 approximately 80 % of Europeans will be living in urban areas (, , ).
From a social perspective, landscape fragmentation exacerbates social and economic divisions and the alienation of man from nature (). This calls for approaches and strategies that overcome fragmentation and enhance functionality, including the development of structural and functional linkages among ecosystems through networks of ecological and human-based components (, ). A range of measures exist that can enhance such linkages while reducing the effect of landscape fragmentation. These measures take different names and definitions according to the scale at which land-use planning is undertaken: from local to regional/national/trans-national level (, , , ).
Improving the functional and spatial connectivity of landscapes is a prerequisite to its ability to mitigate and adapt to climate change and in turn to increase the value of the goods and services that ecosystems provide (, , , , ). In respect of spatial connectivity there is increasing research on the subjects of landscape fragmentation and connectivity (e.g., , ). Landscape fragmentation occurs when areas of continuous natural ecosystems are broken up into smaller elements as a result of new landscape developments and changes (), creating new edges between land cover types (, ). Isolated, fragmented populations are more sensitive to climate change (, ). Recent studies on landscape ecology have clearly brought a new light on the subject of connectivity and suggested several measures for conserving biological and landscape diversity (, ). At the landscape scale level, GI is one of the possible measures in tackling biodiversity conservation and other ecosystem services, such as recreation and accessibility to natural resources.
At the local and regional scale, strategies to counteract spatial fragmentation take the form of greenways, green belts, and green networks (, , ). These are land-use planning designations designed to protect and enhance areas of unmanaged and managed urban green-space, naturally regenerating brownfield land and undeveloped, forest or agricultural land. Urban Planners see concepts such as greenways, green belts, and green networks as a way to improve accessibility to green and open spaces close to where they live, and to link together rural and urban areas (, , ).
When land-use planning occurs at the larger scale, new strategies are needed to organize and link together the spatial assemblage of ecosystems that support regionally significant processes and provide services across whole landscapes (, ). An emerging approach is to consider the landscape as an overall system of ecosystems in which single components interact with each other through a multitude of ecosystems and landscape elements that contribute to create a Green Infrastructure (, , ).
Human health, well-being and Green Infrastructure
Green Infrastructure (GI) is considered as supportive of ecosystem services whilst simultaneously contributing to many health benefits which encompass physical, psychological and socio-economic outcomes (, , ). Health benefits derived from GI exist not just at the local level, but also at the neighborhood, city and regional levels. For example, GI supports human health and well- being of local communities through the presence of more cohesive places to live, work and recreate and connection to nature (). Recent studies have proposed GI as a way of engaging people with the rural landscape () as the management of GI can provide cultural, ecological, and psychological linkages between people and the environment.
Forest Research () grouped the many potential health and well-being benefits of GI into three main categories: (1): increased life expectancy and reduced health inequality; (2): improvements in levels of physical activity and health; (3): promotion of psychological health and mental well-being. Improvements in physical activity and health and the promotion of psychological health and well-being have been grouped together under the term “Green Exercise” (). The creation and management of GI in connection with territorial planning can be used to enhance landscape connectivity, and hence provide greater access to individuals to undertake green exercise. An example of this is the creation of new cycle-ways through tree-lined corridors which link residential areas to employment sites and retail centres.
Green Infrastructure and territorial planning
Green Infrastructure (GI) differs from other approaches in landscape planning because it considers ecological and social values in combination with other land use developments (). Used in connection with territorial planning different types of landscape elements may enhance connectivity (, ) and purposely support the restoration of landscapes to provide optimal habitats and conduits for species ().
The various policies, plans and related activities incorporated in GI are carried out at spatial scales from the local neighborhood through the regional scale to the trans-national. The buildings blocks of GI such as tree lined streets and neighborhood parks exist at a local scale, but the linkage of these creates synergies and higher level effects that have significance at a scale greater than the local (, ). The implications of this on planning are considerable and suggest that GI plans should be nested at a variety of spatial scales from the local to international level, each having a relationship with the next tier. This key point is picked up by the EEA () which identifies three spatial groups (i): local, neighbourhood and village scale; (ii): town, city and district scale; (iii): city-region, region and national scale.
Plan nesting is common in all forms of Government with strategic approaches lying on top of delivery plans at smaller scales. The authors believe that that the city region, an urban conurbation and its adjacent wild-land urban interface, appears to be an especially useful level to consider GI planning. The city-region is large enough to be strategic with identifiable ecological hubs and links yet not too large to be remote from community level activities and local delivery plans that consider green-space as public amenity.
Green Infrastructure framework
The EEA report () proposes that Green Infrastructure (GI) may act as a: (a) strategically planned and delivered network of high-quality green spaces and other environmental features; (b) delivering multifunctional benefits; (c) helping to deliver place-making; and (d) delivering “smart” conservation. It also proposes that GI benefits could be presented in terms of ecosystem services as this provides a relatively consistent and effective language that also has growing resonance with policymakers and other stakeholders. However, GI includes the spatially explicit delivery of ecosystem services - this is the difference and added value compared to the more general and implicit description of ecosystem services. As an example this can be seen through catchment management protection of water resources through changed land management practices such as new afforestation upstream of cities. Hence GI can be used to show benefits and deficits on local, regional and national levels, and therefore is closely linked to planning, decision-making and policymaking.
To support the process of developing and delivering GI, we propose a conceptual Green Infrastructure Framework (GIF) embracing a multi-functional, multi-scale and temporal approach (Fig. 1) which advances the EEA guiding principles and focuses afresh on the link between ecological and social factors argued by Benedict & McMahon (), Weber et al. (), Davies et al. () and Tzoulas et al. ().
The proposed GIF consists of five main blocks each one corresponding to a specific function or bundle of functions. Each block is directly or indirectly linked to the others to mark the interrelation between the various functions and benefits related to GI. Following the guidelines from the Millennium Ecosystem Assessment (), the GIF focuses particular attention on the linkages between ecosystem services and human well-being.
Human well-being refers to a set of basic elements for a good life, freedom to act and make choices, good social relations and security (). Recent studies demonstrated how human well-being is dependent upon multiple and often interrelated ecosystem services (, ): for example changes in regulating services, such as climate fluctuation, could affect the rate of floods and landslides thus having negative effects on people’s sense of security and well-being.
In addition to ecosystem services and well-being, the framework considers as key functions of GI those related to biodiversity, social and territorial cohesion, and sustainable development (, ).
Biodiversity concerns the variability among living organisms and includes diversity within and between species and diversity of ecosystems (). High levels of biodiversity can mitigate disturbances, making ecosystems more resilient and likely to provide services in the long term (). GI can provide habitats for a wide range of species thus supporting biodiversity at ecosystem and landscape levels (, ).
Social and territorial cohesion is a multi-faceted concept covering different phenomena related to people cooperation and territorial integration in cross-border and transnational regions (, ). In this view, social and territorial cohesion deals with the social processes that affect individuals within territories, such as social participation and community engagement which draw people together to work for the benefit of others (). Following this perspective, GI can foster social and territorial cohesion between communities, promote polycentric and balanced territorial development, and encourage integrated development in cities, rural and specific areas.
Sustainable development can be defined as the process of balancing the fulfilment of human needs with the protection of the natural environment. Sustainable development refers to the management of renewable resources without compromising the availability of these resources for future generations and the survival of other species and natural ecosystems (). GI supports the sustainable provision of ecosystem goods and services while enhancing biodiversity (). GI also promotes regional development in countries and regions.
A GI that supports ecosystem services, biodiversity, social and territorial cohesion and sustainable development creates the environmental settings for human well-being and community health ().
Besides multi-functionality, the GIF brings a multi-scale perspective to the subject of GI as envisioned by the EEA (). In other words, the framework recognizes the importance of the scale at which land-use planning is undertaken and supports the idea of having the same approach and bundle of functions applied at different spatial and temporal scales (Fig. 1). In this view, the GIF can support long-term plans and decisions on new GI from local to regional, national, and trans-national level.
Through the framework, existing GI and its functionality can be assessed. Moreover, the framework may assist planners and managers in developing GI plans and delivering multiple benefits to communities (). At the local scale the GI components are coarsely defined units of individual green-spaces. As the scale increases the resolution becomes progressively finer and a network is revealed.
The time axis indicates that the model develops through time; if the GI components are progressively establishing (e.g., growing connections, increase biomass) the services and benefits can be considered as increasing as established landscapes provide greater ecosystem services than new ones (). If the GI components are declining the reverse is true. The time axis is neither a measure nor proxy for improvement or decline; it is indicating whether within any given time frame, the strategies and projects in place are driving improvement or decline in GI networks. The time axis can be large since GI networks establish and decline over long time-frames. Major events (e.g., storms) and driving forces (e.g., forest fire), which may be natural or human influenced, can change the status of the GI rapidly.
Review of examples of GI approaches in Europe
To contextualise the Green Infrastructure Framework (GIF) a review of case studies in Europe was undertaken through a combination of study methods including a document review, web analysis, desk study and review of public sector strategies at the regional, national and international level (see Tab. S1 in Appendix 1). Two starting points were identified for continent wide discussion on Green Infrastructure (GI) in Europe.
The first is Europe’s Natura 2000 network which encompasses more than 25 000 sites, spread over 27 member countries, covering almost a fifth of the European territory. Conservation of landscape features that support species movement and dispersal is particularly important as a means of supporting the coherence of the Natura 2000 network (). However, many studies and reports argued that such network might not establish its coherence as much of Europe’s landscape is highly fragmented and under intensive land use, transport routes and urban sprawl (, ). The Natura 2000 network can be interpreted as GI cells that already provide ecosystem services, such as food, air quality, carbon sequestration, flood management, water treatment, local climate conditions, soil erosion prevention, etc. (), but the system benefits at a continental scale could be greater if there was more network connectivity between them.
The European Landscape Convention which is aimed at the protection, management and planning of landscapes as well as raising awareness of a living landscape is another GI consideration. Importantly, the Convention is not only aimed at designated landscapes but also ordinary landscapes both in urban and rural areas (). Since GI includes the landscape scale approach many examples of GI transnational and national programmes in Europe can be found. As the landscape scale becomes more finely delineated towards the city or local level the linkage between different landscape units becomes more pronounced. There appear to be significant benefits to be gained from a GI approach, both in terms of planning landscape enhancements, using green spaces to buffer the most sensitive areas closer to urban settlements (e.g., wild-land urban interface).
Among the examples of GI projects in Europe, the authors considered twelve examples across four levels of spatial (planning) scale: transnational, national, city-region and urban (Tab. S1 in Appendix 1). For each example, the main documents describing the vision and objectives were reviewed. Using the authors Green Infrastructure Framework (GIF), each example was then analysed according to five functions/bundle of functions: (i) ecosystem services; (ii) biodiversity; (iii) social cohesion; (iv) sustainable development; and (v) human well-being. It was then reported whether or not the example gave indications on such functions. By using the GIF as an analytical lens the following observation were made.
Social and territorial cohesion features throughout all the examples. On closer analysis the socially cohesive elements vary according to the scale of the project, for instance the social and territorial cohesion between populations across country boundaries is the principle requirement at the transnational scale and by contrast within and between local communities at the scale of urban programmes. Given the strength of the relationship it is possible with confidence to conclude that the relationship between GI and social and territorial cohesion is already seen as a “strong rationale” and “policy driver” for those developing GI projects at all spatial levels.
The relationship between biodiversity and GI was the second strongest relationship (10 out of 12) and appears to be universally sought for at the City region, national and transnational level, however the relationship at the urban programme level is much weaker. This suggests that social cohesion and biodiversity considerations are stronger for those actively developing projects at the urban programme level and also confirms earlier practitioner led observations (). This observation also supports the position of those arguing with local politicians for a greater level of understanding on the benefits to communities of being “close to nature”.
Sustainable development and GI is focused on the city region and urban programme level. This can be explained by the fact that the land-use policy planning system is used in most European countries to direct and moderate on all forms of development (e.g., housing, industry, energy infrastructure). This is generally delegated to city and local authority administrations although sometimes, as in the case of the UK, with national guidance.
Human well-being and GI is strongly focused on the urban programme scale. This can be explained by the fact that most urban health interventions seek to raise the health expectations of those disadvantaged communities who through their lifestyle, educational attainment or housing conditions have considerably lower life expectations and lower age mortality than the urban average. Green improvements are known to lead to an improvement in human health and lower the costs of primary health care and it appears from this analysis that this relationship is understood by those developing urban green infrastructure projects.
The least consistent relationship is that between GI and ecosystem services. There is no apparent trend. It is thought that the few connections found between GI and ecosystem services might reflect the influence of policy makers or practitioners who are already aware of the relationship between ecosystem services and GI and that wider knowledge amongst the professions remains low. Given the clear link now being made between the two (, , ) and the notable link that the GI approach can be a major planning and implementation tool to maintain and enhance ecosystem services to urban populations; there would appear to be a strong case for the European Union to be strongly investing in the training of key urban professionals, applied research projects and pathfinder projects in member states where results will lead to a change in practice. A description of the examples is reported in the supplementary material (Appendix 2).
In summary the investigation revealed that one of the most effective ways to build up GI is through an integrated approach to spatial planning (). Policies that adopt a spatial planning approach can improve landscape coherence and connectivity inside and outside protected areas and help establishing multifunctional landscapes. Therefore, GI should not be interpreted in a narrow sense, but as a means to illustrate that habitats, species and landscapes must be part of a functionally coherent network that delivers valuable services and goods ().
Discussion and conclusion
Europe is a densely populated continent and much of the land is in active use (). Land-use changes are having considerable effects on ecosystem services and human well-being and as a result landscapes and ecosystems in Europe are under pressure. Within Europe and in the context of Green Infrastructure (GI), there is a good deal of policy making and practitioner led activity at all levels; international, national, city region and local. There is evidence that funders and the agencies leading these activities have designed their initiatives to address the ecosystem consequences of environmental pressure. In this respect the GI approach is a notable contribution to the planning of ecological connections at many scales which meld with urban form to offer the prospect of a more sustainable landscape for well-being and biodiversity. This analysis is considered the major reason why the GI approach has been taken up rapidly by planning systems in many countries and by the European Union. Since developing and delivering GI involves the adoption of an integrated territorial planning approach supporting not only ecological coherence between protected and unprotected areas, but also a wide range of functions and benefits to society then key challenges can be identified for the European Union’s environmental policy agenda. The principle one is how to integrate ecological networks (Natura 2000 sites) into a broader GI that maintains ecological functions in combination with multi-functional land uses ().
In a practical sense the city-region level appears to offer an especially attractive scale for GI planning by being capable of strategic significance and relevant to local communities at the same time. However, GI can be discerned at all levels with the local level possessing the coarsest resolution, where individual component such as “green-spaces” are readily identifiable through to the international “continental” level, where the resolution is at its finest. This implies that only by linking GI plans together hierarchically it is possible to ensure a seamless transition through the different scales of resolution.
The European experience of GI has much to offer to other continents, not least because the approaches taken in Europe have proven highly adaptive to national and regional requirements. Whilst the idea of GI did not originate in Europe, it is perhaps in Europe where the approach has received such a high level of attention, experimentation and research interest. The challenge for researchers is not so much what to include but what to leave out of the discourse.
In researching examples of GI initiatives across Europe and then combining those with the results of a detailed literature review new insights start to appear. This has led to the development of a proposed new Green Infrastructure Framework (GIF). This is offered to policy makers and researchers for use and further exploration. The GIF is seen as a unifying human centred approach to multi-scale (spatial and temporal) planning for “ecosystem” and “well-being” services. The framework model operates at all spatial scales and is “nested” and can be allied to the key opportunities identified by the EEA (). The inclusion of a time axis places the planning of GI into the temporal dimension of improvement and/or degradation or indeed both as some elements may be progressing whilst others are contracting at the same time. The GIF is built upon existing GI criteria including ecological hubs, links and multi-functionality in land-use management but adds “drivers” for GI planning; ecosystem services, human well-being, social cohesion, biodiversity and sustainable development. A well rounded GI plan should be expected to deliver on all these drivers at different scales and through time.
The prospect also exists that as the costs and benefits of ecosystem services become ever more accepted within decision making and resource allocation, resources in support of the GI approach will also be strengthened.
We are grateful to the two referees for their constructive comments on the manuscript. This study was carried out within the project PRIN 2009 “in_FLAMING: Developing innovative models and techniques for integrated fuel management for fire prevention in Mediterranean and temperate forests” (national coordinator: P. Corona) funded by the Italian Ministry for Education, University and Research.