COSTUMBRES Y TRADICIONES

1) Definition

Urban green space is used in a general sense by its literal meaning: the green (vegetated) spaces in urban areas. Its inclusiveness allows an intensive use in urban planning, landscape planning and ecology researches, but sometimes it is not explicit enough for either perspective. Like ecosystems and landscape (units), “urban open space” is the more common term in the context of urban planning. “Open space” was originally defined as “any land, weather enclosed or not, on which there are no buildings or of which not more than 1/20 part is covered with buildings, and the whole of the reminder is laid out as a garden or is used for purposes of recreation or lies waste and un occupied” in The 1906 Open Space Act of London, one of the first cities to value the non-built areas in the high cost of urban land (Turner 1992). To be short, open spaces are “the totality of land units with mainly non-built soils”; such soils are the resources and substrate for “biological, hydrological and other functions that constitute the natural components of agriculture, nature conservation, forestry and many other services” (Bomans, Steenberghen et al. 2010). As the contrary and reminder of built environment, urban open space emphasis on the low level of artificial interventions and the maintenance of naturalness (Maruani and Amit-Cohen 2007).

However, “urban green (open) space” is also commonly used and considered the subset of open space which is dominated by natural elements, since specific objects of open spaces relay also on scale and range. At local scale, artificial elements like streets and squares are necessary components of urban open space; while in urban and above scales, the natural elements, like forest,

farmland, river and so on, are the core functional parts. To avoid such confusion, “urban green (open) space” is mainly used in the thesis.

Another category is public and private open space, the two mutually connected and penetrated types. Private gardens and public lawns may be distinguished based on landownership, but they are connected mentally and ecologically. A park could be a public space to meet strangers, and also a personal place to hide away from noise and traffic. In the meantime, parks and gardens regardless of their size, are components of the urban landscape mosaic, as well as unique urban ecosystems.

2) Content

Access to some form of nature as a fundamental human need is the very base of open space (Thompson 2002). However, after more than a century of development, the current functions of urban green open space has become a vague combination of all kinds of functions, services and benefits/values of related ecosystems (De Groot, Alkemade et al. 2010). The content has been increasing with the upgrading of open space planning models from single points to complex networks, as well as the changing of service object from a bunch of people to both society and nature. The relevant personnel started with urban planners, soon added with landscape architects and now also with ecologists and more others.

Most requested functions of green open space in early times belong to “cultural services” or “informational functions”. For instance, the “public walk”, a purpose of the allocation of public open space in the middle of 19th _{century in London, could be translated into the function or service}

of “recreational activities” and “aesthetic appreciation”. Some demanded functions also related to the “regulating services”, like “public health” is the benefit people would get from “Air purification” and “waste treatment”. Some functions were already used but may be excluded out of urban areas, like “food provisioning” which came back to urban context in recent decades. Some functions only exist after the the planning object has shifted from “human-centered” to “society-nature system”. Many green functions have influences from conservation biology, like green networks/webs will benefit for “genetic diversity” and “Habitats for species” (Turner 1992).

Some traditional green functions and demands are complicated and not easy to classify. “Equity” has been the topic at the beginning of open space planning, and could be reflected by the still used “urban green standard”, which try to achieve relatively equal accessibility (maybe also quality) for everyone by regulating the service range, population and minimum area of public open spaces (Turner 1992). In the past decade, “environmental justice” attract more attention again and over-quality of open space may lead to “green gentrification” (Campbell 1996, Wolch, Byrne et al. 2014). Another case is the “segregation” function used by planners. Street trees could “reduce noise”, service for “air purification”, “local climate regulation”, “carbon sequestration”, and as disservice

to “block view”(von Döhren and Haase 2015). From a larger scale, the green structure is not planned for ecosystem only, but play a vital role in the formulation of urban and regional development.

3.1.4 Summary

One key question of this section is, what/which functions should be included when talking about the multifunctionality of urban green open space? It is clear the ecosystem services, landscape functions and functions of urban open space have different focus and background, but they are not distinct with each other. Fundamentally, they have basically the same physical base, the non-built use of land. The advantage of landscape functions lies in its long study history and strong connection with natural science; the urban green open space linked directly towards land use and planning, focus on the improvement and balance with built environment; the concept of ecosystem service is better described as “the missing link” between nature-centered and human-centered perspectives (Bastian, Haase et al. 2012), and unified multiple perspectives in its widely accepted categories (Fig 3.1.1).

From a planning perspective, for which drawing lessons from other disciplines is part of the work, a practical joint view and a combination of the various approaches would be a better option to complete and supplement existing shortages towards better future. The included functions of a multifunctional urban green open space must draw inspirations from all useful sources and further test in real application.

Nature-centered ———— Human-centered Function --- service --- value/benefit

Landscape functions Ecosystem Services Functions of urban green open space

Fig 3.1. 1 The different focuses of concept, dashed ring refers to the possible maximum range of multifunctionality. Based on Andersson 2015 and others and draw by author.

Another critical condition is the scale or context suitability hidden in the definition. Scale refers to the multi-layer spatial network of urban green space. As pointed out by GI concept, it is a system consists of elements from any scale and scope, from small patches to community garden or the national conservation area. However, green spaces are spatially continuous but functionally differed depend on scale and context. For instance, most cultural services matter more on local scale, while provisioning services could be scalable or more meaningful on regional scale (Andersson, McPhearson et al. 2015). Moreover, different methods should be applied on different scales, like some argued that city level analysis on ES should focus on the generation and distribution, for which the ecological analysis could be used; while on local level, it is important to trace the consideration of actors and specific contextual limitations, using ethnography, interviews and archival methods (Ernstson 2013). By doing this, the smaller scale is not simply amplified from a larger one, but more details will be added to the whole picture and helps the in-depth interpretation. In this way, scale will be the leading dimension to understand functions (from an objective aspect) and aims (from a subjective aspect) at different level.

By using the broader definition of ecosystem as above, ecosystem services in either MA or TEEB report should be considered as a general collection of all possibility. For instance, ecosystem services in urban areas will pay more attention on the ones directly related to human well-being, like air filtering, micro-climate regulation, noise reduction, rainwater drainage and so on(Bolund and Hunhammar 1999). Some studies applied the full package of all services for policy or planning analysis (Wilkinson, Saarne et al. 2013, Hansen, Frantzeskaki et al. 2015); most quantitative evaluation selected about 10 to 15 services due to local conditions and mostly the availability of data (Raudsepp-Hearne, Peterson et al. 2010, Turner, Odgaard et al. 2014, Yang, Ge et al. 2015); only few considered weight or used certain algorithm for grouping(Koschke, Fuerst et al. 2012).