The benefits human beings may obtain from the semi-natural environment (e.g., urban green space) can be referred to as ecosystem services (Millennium Ecosystem Assessment, 2005). Defra (2011) defines ecosystem services as the benefits individuals gain from the goods and services (Table 2.3) produced by nature and its natural systems (Defra, 2011). The natural resources such as timber and water, and functioning natural systems such as healthy fertile soils, clean water (Walsh et al, (2012) and air, and a
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regulated climate are essential for human wellbeing, security and economic prosperity (Millennium Ecosystem Assessment, 2005). A high biodiversity helps to sustain the natural environment and is thus an important factor for ecosystem service provision. For example, a diverse range and a substantial number of urban trees support wildlife and human well-being.
Table 2.3. Examples of ecosystem services associated with urban water components together with ecosystem goods, benefits and possible units of measure, (Adapted from: Lundy and Wade, 2012).
Categories of ecosystem services
Types of ecosystem services
Ecosystem goods and benefits
Examples of units of measurements
Supporting services
Primary production
The goods and benefits of sustaining services are their role in facilitating other services to take place
g C m-2
Production of oxygen g O2.m-2
Soil formation cm year-1
Water cycling % permeability
Provisioning of
habitat hectares
Provisioning services
Food Meat and vegetables tonnes/hectare
Water Portable and non-
portable water litres/hectare
Renewable energy Hydropower Mega watts
Genetic resources Pollutant degrading
species cfu/ml
Regulating services
Climate regulation Reduced urban temperatures
oC
Water regulation Reduces runoff
volumes/velocity m
3; ms-1
Erosion control Stabilisation of
sediments g/m
2 Water purification Removal of pollutants mg/l
Cultural services
Spiritual value Mental well being
Number of users (reduced demand on mental services) Educational value Increased environmental awareness kg (reduced littering of water bodies) Aesthetics Increased house prices % (increase in
house price
Recreation Physical well being % (reduced levels of mortality)
Costanza et al. (1997) introduced the concept of ecosystem services, the associated values and corresponding categories. The ecosystem approach is a strategy for the
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integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way. The increasing human population size, economic growth and global consumption patterns place pressure on environmental systems. It follows that the provisioning of ecosystem goods and services is affected (Seppelt et al., 2011). The concept of ecosystem services stayed much the same until de Groot, Wilson and Boumans (2002) published a framework diagram and a table in an attempt to distinguish between ecosystem functions, processes, goods and services. Brown, Bergstrom and Loomis (2007) subsequently defined ecosystem services as the results of ecosystem processes that either directly sustain or enhance human life or maintain the quality of ecosystem goods.
A number of official documents such as the Natural Environment White Paper (Defra, 2011), the UK National Ecosystem Assessment (2011) and TEEB (2011) have identified four broad categories of ecosystem services generally referred to as supporting, regulating, provisioning and cultural. All existing ecosystem services are strongly linked to one another and to other types of ecosystem services. The impacts of supporting services on nature take place over a long period of time and are indirectly beneficial to human life. They refer to all ecosystem services that provide a basic infrastructure of life (UK National Ecosystem Assessment, 2011), and it is due to this that all other ecosystem services, which do not fall within this category, depend on their existence for their own continuation. Supporting services are strongly interrelated to one another by an extensive range of chemical, physical and biological interactions (UK National Ecosystem Assessment, 2011).
Tzoulas et al. (2007) provided a detailed literature review on ecosystem services in the urban environment. TEEB (2011) and other guidance documents such as Moore and Hunt (2012) have produced list of ecosystem services. TEEB (2011) proposed a
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comprehensive list of ecosystem service variables of generic nature, while Moore and Hunt (2012) chose a smaller set of variables particularly adapted for constructed wetlands and ponds.
Euliss et al. (2011) proposed a modeling framework to allow estimation of conservation practice and program effects on various ecosystem services at different temporal and spatial scales. This modeling approach could provide the broad view needed by decision-makers to avoid unintended negative environmental outcomes, and to communicate to society the positive effects of conservation actions on a broad suite of ecosystem services.
The ecosystem services classed within the category of regulating services are very diverse and include all those ecosystems that provide benefits through the regulation of ecosystem services. The goods that are obtained from ecosystem services are referred to as provisioning services (UK National Ecosystem Assessment, 2011). The goods obtained can be distinguished depending on the degree of human interference. Goods that have been yielded from nature with minimal interference from humans can be referred to as ‘natural production’, while goods that have had a higher level of human interference, such as the use of fertilizers and pesticides, can be referred to as ‘joint production’ (Slootweg et al., 2010).
Ecosystem services, which are present due to environmental settings that provide recreational areas where individuals can interact with nature and each other (UK National Ecosystem Assessment, 2011), find spiritual fulfillment and mental development are known as cultural services. These services are, however, rather subjective, dynamic and difficult to quantify. However, Sander and Haight (2012) estimated the economic value of cultural ecosystem services in an urbanizing area using hedonic pricing. They found out that many aspects of the aesthetic environment significantly impacted home sale prices.
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The continuing increase in urban population is putting a considerable strain on provisioning services such as food, fibre, water and energy, preventing the efficient delivery of numerous regulating, supporting and cultural services. Urban areas are increasingly being faced with issues such as elevated surface runoff and more heat island, which result in alterations of the local energy exchange and hydrology, thus having a negative impact on regulating services for climate, soil and water quality, and noise. In the UK, roughly 30% of ecosystem services have been identified as declining, while many others are considered to be in a reduced or degraded condition (UK National Ecosystem Assessment, 2011).
A more resilient semi-natural environment needs to be created to protect ecosystems to counteract the negative impacts of urbanisation. This can be achieved by bettering habitat management to improve the quality and size of existing wildlife sites, creating physical corridors to improve connections between SUDS sites, creating new habitats by planting more urban trees and lessening the strain on wildlife by reviving the wider environment (Lawton et al., 2010). Some success in improving the ecological status over the past ten years has been accomplished through the Water Framework Directive (European Union, 2000) by improving the quality of many water bodies (UK National Ecosystem Assessment, 2011).
Ecosystem service assessment is dynamic considering that the built environment constantly changes (Eigenbrod et el., 2011) and the scientific knowledge of associated processes develop further. For example, surface permeability and green roof runoff estimates may be different in the future. It follows that SUDS recommendations will change over time
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