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Planning green space networks for urban biodiversity

Urbánní ekologie
Planning green space networks for urban biodiversity

Sustainable urban planning recognises the importance of green space networks to conserve biodiversity. A recent study in China has assessed whether a development plan for Jinan City improves the city's urban green networks.
An essential part of sustainable urban development is the conservation of biodiversity. Green space networks (green spaces connected by 'corridors') are used to protect wildlife and threatened habitats. Corridors support populations by maintaining landscape connectivity and allowing species to move between isolated habitats.
Green space networks also contribute to climate change adaptation by cooling and improving air quality, and can act as a good example of 'Green Infrastructure'. Green Infrastructure is a key tool to address the ecosystem services dimension of biodiversity which links various ecosystems into a network to maximise their functions and services. A recent European Commission Communication1 foresees an EU strategy on Green Infrastructure.
In this study, the researchers assessed whether green spaces proposed in the development plans for Jinan City (2004 to 2020) would actually improve the green space network by comparing the pattern of green spaces existing in 2004 with the proposed stage of development of green space patches and corridors in 2010. The built-up area has expanded from 24.6 square kilometres in 1949 to more than 190 square kilometres in 2003 and scenery forest dropped by 13 per cent (about 1550 hectares) between 1989 and 2004.
Ideally, all corridors directly link green spaces. In real landscapes, however, blockages can occur. The researchers first identified potential corridors containing the least amount of obstruction through modelling. Further modelling determined the relative significance of each green space and corridor to help decide which corridor to develop first, as there is likely to be more than one corridor connecting up green spaces.
Overall, the study found the amount of habitat fragmentation in Jinan City has declined and connectivity has increased under the proposed urban green space system. In particular, plaza and roadside green spaces increased, although the green networks only showed marginal improvement.
Potential corridors were identified and amounted to about 11 per cent of the total study area, or about 5664 hectares. The main corridors were found in roadside green areas, followed by riverside green space, and then parks that connect other green spaces, which are primarily composed of scenery forest.
Nevertheless, problems were identified in the proposed networks. The corridors are mainly forested but agricultural land or construction areas interrupt these connections in some places. The researchers suggest these gaps should be closed to improve connectivity.
A further problem occurs when scenery forest is surrounded by residential areas. Potential corridors are not able to connect these patches to other green areas except by a roundabout route. In these cases, new green space corridors or patches are needed for an efficiently functioning network. In addition, the study suggests links to green areas beyond the study area are important for wildlife dispersal and migration, although connections to these areas are threatened by urban sprawl.

  1. See: http://ec.europa.eu/environment/nature/biodiversity/policy/pdf/communication_2010_0004.pdf
Source: Kong, F., Yin, H., Nakagoshi, N., Zong, Y. (2010). Urban green space network development for biodiversity conservation: Identification based on graph theory and gravity modelling. Landscape and Urban Planning. 95: 16-27.
Contact: fanhuakong@163.com

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