The Ecology of Urban Areas and Their Functions for Species Diversity

Transcription

1 The Ecology of Urban Areas and Their Functions for Species Diversity Peter Werner Institute for Housing and Environment Research Institution of the State of Hesse and the City of Darmstadt and COmpetence NeTwork URban ECology - CONTUREC 1

2 Background A Review about Biological Diversity and Cities Participation in the expert working group Singapore Index on Cities Biodiversity 2

3 Biodiversity - Cities There is a European and North American view. NASA Our common scientific knowledge and perception are determined largely by two taxonomic groups, higher plants and birds. Reichholf 2007 Cities, showing species richness higher than the average, are often cities with universities housing numerous biologists within their borders. M. Schwarze 3

4 Scientific challenges to get a more complete, global picture; to develop frameworks which enable us: to compare cities round the world: to encourage tailored investigations; to identify appropriate indicators for monitoring systems; to provide principle guidelines for biodiversity management. 4

5 The ecology of urban areas and their Functions for species diversity Embedded City Urban Matrix Urban Patches (Green Infrastructure) Conclusion 5

6 Embedded in various landscapes density of human population arrangement of buildings, technical infrastructur, and open space specific climate specific water budget contamination of air, soil, and water disturbance fragmentation introduction of species Klett-Verlag Klett-Verlag Klett-Verlag boreal forest desert savanna 6

7 Embedded in various landscapes wikipedia Fragmentation of forests Particularly open green space Increase of disturbance Urban heat island Extended vegetation period Winter roost.. wikipedia 7

8 Embedded in various landscapes Klett.de Alou Lah Increased vegetation Artificial water ponds Irrigation of green areas Climate more humid Habitats for generalists increased More diurnal animals.. wikipedia 8

9 Embedded in various landscapes Norbert Fink claranet Increased vegetation Artificial water ponds Irrigation of green areas Climate more humid.. wikipedia 9

10 Embedded in varying landscapes native species source sink source sink sink source sink source non-native species >10,000 years Early farming phase > 5,000 years Mesopotamia > 2,000 years Mediterranean, Asia 1,000 years Middle Europe 500 years North America 200 years Australia 10

11 Native species in varying landscapes City Area km 2 Number of plant species % native species incl. archaeophytes Rome (Italy) 1,272 / 300 (city) 1, Cheon-ju (South Korea) Berlin (Germany) 892 1, New York (USA) 1,214 / 789 (terrestrial) 2, Christchurch (New Zealand) 1,426 /452 (city)

12 Cities and regional species pool City Area km 2 Number of bird species % of regional species pool St. Petersburg (Russia) 1, Warsaw (Poland) Valencia (Spain) Rom (Italy) 1,272 / 300 (city) Munich (Germany)

13 Cities are located in naturally rich landscapes. The relationship to the regional species pool can be a useful indicator. We have to realize that cities are embedded in varying landscapes natural landscapes (biomes); cultural landscapes (type of use and time scale). Embedded Cites Planungsverband Ballungsraum Frankfurt/Rhein-Main 13

14 What is the urban matrix? A town or city can be viewed as a complex habitat mosaic and its entirety is the urban matrix. Frankfurt mosaic of the urban fringe 14

15 What is the urban matrix? A town or city can be viewed as a complex habitat mosaic and its entirety is the urban matrix. All areas of the urban environment that are not patches of green areas (remnant vegetation). Frankfurt mosaic of the urban fringe 15

16 Underestimation of the urban matrix Three examples (1) Domestic gardens: in the United Kingdom between 19% and 27% of the area of towns and cities is taken up by domestic gardens (Smith et al. 2006). 16

17 Underestimation of the urban matrix Three examples (2) Apartment buildings: in German towns the comprehensive size of the private green areas between those buildings is more than double that of public green (Werner 1999). 17

18 Underestimation of the urban matrix Three examples (3) bats: the effective size of parks have been larger than the actual size of those parks depending on the amount of suitable habitats in the surrounding area (Loeb et al. 2009). Nikolaus Heiss 18

19 Describing urban areas Land use types Gradients Map section of the city of Hannover (Germany) centre suburbs outskirts village Biological performance (Ahuis et al. 1993) 19

20 Species-area-relationship Higher Pants (Polish and German cities) number species Hot spot in middle Europe (?): Above that line hot spots of biodiversity All areas > 1,300 vascular plant species per 1,000 km² Berlin Berlin is a hot spot of biodiversity: Warsaw y = 463,54x - 238,22 R 2 = 0,562 1,393 vascular plant species on 892 km² 0 0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 log area km² Pysek 1998 and own data 20

21 Proportion of vegetation Quantity and quality of the vegetation in the urban matrix effect: the permeability or vice versa the resistance of the urban matrix; the proportion of native species in the matrix; the occurrence of specialists in the matrix. Hannover (Germany) Lübeck (Germany) Environmental atlas of Berlin map of the proportion of impervious surfaces 21

22 Green infrastructure Remants of pristine nature, parks, public green areas, green corridors, wastelands and other green areas are the skeleton of biodiversity in urban areas. Wildes Berlin, Chris Packham 22

23 Green infrastructure Investigated urban and suburban parks in Flandern (Belgium): = 0,03 % of the total area = 29 % of all wild vascular plants = 49 % of all breeding birds (Cornelis & Hermy 2004) 23

24 Four forms of nature The urban patches represent four basic forms of nature (after Kowarik 2005): old wilderness : remnants of pristine nature traditional cultural landscape : continuity of former agricultural or forested land functional greening : urban parks, green areas and gardens urban wilderness : new elements by natural colonization processes particularly distinct on urban wastelands 24 Ulmer-Verlag

25 Habitat quality The habitat quality of patches depends on: Soil Structure Size Age Disturbance Connectivity 25

26 Habitat age Three aspects of age: pristine remnants of native vegetation; 26

27 Remnants Rio de Janeiro (Brazil) - the remnant forests of the Mata Atlantica; Singapore - the evergreen forests of the Botanical Garden; Caracas (Venezuela) - the National Park El Avila with its rock faces; Perth, Sydney and Brisbane (Australia) - various remnants of bushland; York (Canada) and Portland (USA) - remnants of natural forests in York (Canada); Edinburgh (Scotland) - rock faces and outcrops. 27

28 Habitat age Three aspects of age: pristine remnants of native vegetation; constant use and maintenance over decades or even centuries; 28

29 Constant use and maintenance Royal Parks of London; Semi-natural forests in the precincts of temples and shrines in Japanese cities Archeaological sites in Rome. Greenwich Park London Meiji-Shrine Tokyo Rome 29

30 Outside of the city Cites are highly dynamic systems, change and high disturbance are aspects which characterize a city. It is typical for that both urban habitat types, that they are outside of change; outside of high disturbance. 150 years later Berlin-Oranienburg Berlin-Oranienburg 30

31 Habitat age Three aspects of age: pristine remnants of native vegetation; constant use and maintenance over decades or even centuries; succession and emergence of differentiated vegetation structures. Dirk Ingo Franke 31

32 Urban patches and biodiversity structural diversity of the vegetation is one of the most important factors for mobile species; near-natural vegetation increases robustness and resistance to the invasion of alien species; size correlates with an increase in habitat structures and the variety of microhabitats size is a simplification; habitat age has a variety of aspects: pristine remnants, unchanged use, succession and emergence of differentiation; quality of green networks has a structural and functional dimension; many measurements for biodiversity support generalists and alien species and not necessarily threatened native species. Jeff Clow 32

33 The more Principle guidelines structurally complex, larger, older, less disturbed, less isolated a habitat area is, the better are the implications for biological diversity 33

34 Conclusion comparing cities by appropriate indicators, we need models that help us to understand and mirror the causal relationships between urban areas and biodiversity; the problem is that the complexity of determinants and the spatial and temporal dynamic of cities preclude simple lines of argument to explain causal links between biological diversity and cities; the three approaches: embedded cities, urban matrix und urban patches can be a basis to create appropriate models and indicators. 34

35 Thank you for your attention Meyers Medien References in: Werner, P. & Zahner, R. (2009): Biological diversity and Cities. BfN-Skript 245 Werner, P. & Zahner, R. (2010): Urban patterns and biological diversity: A review. In: Müller, N. et al., Urban Biodiversity and Design. Wiley-Blackwell, p