Biodiversity and Urban Streets

Transcription

1 Biodiversity and Urban Streets Urban Street Design for Engineers CPD Session 3 Constituent Elements Engineers Ireland Maryann Harris BSLA MSc Dip Law Past-President, Irish Landscape Institute Parks Services Dublin City Council

2 Where we are: DMURS 2013 No reference to Biodiversity in DMURS. Only reference to Green Infrastructure is in relation to mitigate air pollution. Trees considered as spatial objects, not habitat. Continuous soil planting strips for trees recommended only ref. to soil No consideration of Soils in DMURS SuDS directs to GDSDS (2005) to be revised!

3 Understanding urban biodiversity Biodiversity = all living things includes flora, fauna, soils! Exists at different levels: landscape, ecosystem, habitat Influenced by landscape context, history of city

4 1,400 ha of public parks and open spaces city-wide >2,000 ha of wetlands in Dublin Bay, shallow, large intertidal 2 no. Natura 2000 sites (both SPA and SAC) and a National Special Amenity Area in Dublin Bay 3 main rivers - the Liffey, Dodder and Tolka - all flow into Natura 2000! - all have wild salmon stocks present - only European capital city to have this! Characteristics of Dublin s landscape context Sensitive landscapes with urban impacts

5 How biodiverse is Dublin City? Dublin is 10 th of all major European cities in terms of the area covered by Natura 2000 sites These are sites designated by the European Union for the importance of their habitats/species under EU Birds and Habitats Directives

6 Characteristics of biodiversity in cities 1. Cities often have higher biodiversity due to influences of humans and are often situated in naturally high biodiversity areas e.g. harbours 2. Global and Irish urbanisation phenomenon = 60% of population lives in cities, so urban biodiversity is nature for many an artificial ecosystem 3. Urban biodiversity can be more complex due to multi-causal dynamics, more non-natives, niche habitats 4. Some species adapt to urban conditions better generalists better off than specialists, which become locally extinct 5. Not well-studied, ecological literature based on natural habitats not urban more complex to model

7 Threats to Biodiversity Globally (and Downtown) 1. Habitat loss and fragmentation urbanisation severs 2. Invasive species along transport corridors 3. Population pressure disturbance, pollution, volume 4. Climate Change runoff, heat island effect, CO 2 5. Overharvesting Most of these threats occur in urban areas!!!

8 fragmentation interior habitat edge habitat interior habitats and species decrease edge habitats and species increase

9 EU law and designing to prevent fragmentation Article 10 of EU Habitats Directive requires: land-use and development policies to manage features of the landscape which are of major importance for wild fauna and flora and which by virtue of their linear and continuous structure or their function as stepping stones are essential for migration, dispersal and genetic exchange of wild species Note: this legislation is inclusive of ALL species, not solely designated flora and fauna! Streets can play a role in increasing connectivity of habitats Street design must be informed by landscape features of cities Green infrastructure strategies may exist in development plans or LAP s

10 What is Green Infrastructure? Green Infrastructure = an interconnected network of green space that conserves natural ecosystem values and functions and provides associated benefits to human populations (Benedict and MacMahon, 2006) Emphasis on multi-functional and benefits to us, not just for nature s sake Ecological networks are boosted Cities are more resilient to disasters such as flooding Ecosystem services what does nature do for us?

11 How to build GI into a city Green infrastructure systems are spatially made of: 1. Core areas = nucleus of the network and provide essential habitat for sensitive species 2. Hubs = buffering the core areas, the largest, least fragmented continuous area of forest, wetlands, stream systems, or other native landscape type 3. Corridors = maintain connectivity in the landscape and provide for animal movement, seed and pollen dispersal, and plant migration

12 Green Infrastructure policy in City Development Plan DCC GI Working Group for Plan

13 Overall public open space: 5.09 ha/1000 pop. DCC-owned: 2.96 ha/1000 pop. 22% of the land area within the city boundary zoned Z9 = 2,580 hectares as recreational amenity and open space 25% of city area is private gardens Distribution of Public Open Space Network Areas Zoned in City Development Plan

14 Fundamentals of Urban Streets and Biodiversity Soil sealing and permeability bare ground as habitats Microclimate and trees shelter, cooling, evapotranspiration, energy production and transfer, air purification and filtration Soils for bacterial action to convert waste Water as a resource - stormwater

15 Soil sealing Dublin has 50-79% degree of soil sealing (EU) Bacterial processes in soil can break down and treat waste Soils as a biodiversity resource and a living medium as a buffer Effects on a city paving of front gardens in Dublin Soils management on site

16 Built and green space in Dublin region 2006 (Brennan et al 2009) Red zones show loss of green space Green zones show gains of green space 22% of Dublin city is zoned as green space, but patterns are fragmented 10% open space requirement as national planning policy but no specific guidance on how to structure it The city centre has areas of open space deficits

17 Continuous tree pit (UK) Suds retrofit in an urban street. Source: Susdrain

18 Philadelphia Green Streets watershed project: streets to store stormwater

19 NYC Greenstreets Project: target CSO s on a street basis Courtesy: Jim Mituzas, NYC Parks Dept.

20 Principles of street design for biodiversity Leave strips of soil large enough for vegetation to filter runoff, provide habitat Look at green roofs on a street basis Leave adequate space for trees when designing services layouts Ensure that connections to existing green networks (parks, open spaces, cemeteries, waterbodies) are not severed

21 Principles of street design for biodiversity Take back corners and unnecessary hardscape for increased permeability and living surfaces Provide light and water for living things don t expect growth on north-facing aspects Consider micro-climate e.g. ground temperature can be elevated if shelter and foster insect life Lighting should minimise spill, only light what s needed to be seen

22 Designing for Biodiversity in Streets Adequate budget for site survey, design, landscape elements Adequate time to survey when appropriate, to allow establishment, to not leave as an afterthought Ecosystem services there can be benefits for humans as well as other wild species health, shelter, food resources, quality of life, amenity Look at potential hotspots, where street clusters can augment existing networks, rather than fragmented approach Allow for change and movement from disturbance Leave meaningful space for growth Connect to existing park networks as much as you can

23 Irish Urban Biodiversity Research Project EPA STRIVE Doctoral Programme (2012-B-PhD-10) Enhancing biodiversity potential of urban parks through improved management and public engagement EPA/UCD/DCC partnership Questionnaire to inform Irish guidance document please assist by completing today Survey of Irish professionals whose work can impact on biodiversity in urban areas Thanks!