Tools to Preserve Biodiversity in Urban Fringe Areas

Transcription

1 Tools to Preserve Biodiversity in Urban Fringe Areas Ascelin Gordon RMIT University Re-imagining the Australian Suburb Seminar 18 th October Re-Imagining the Australian Suburb Multi-disciplinary umbrella project at RMIT University, Melbourne Focus on improving sustainability of Australian suburban development 6 projects: Biodiversity management Local government and community governance Eco-homes / EcoFootprint Sustainable urban water systems Ecological sustainability of housing developments Building lifecycle assessment 2 1

2 Biodiversity Planning in Urban Fringe Landscapes: Context Research ( RMIT University (Sarah Bekessy + 2 Postdocs, 1 PhD and 1masters) University of Melbourne (Brendan Wintle, + 1 PhD student) ARCUE (Mick McCarthy) DSE, ARI (Josh Dorrough) Industry Partners DSE - Biodiversity Research Stockland property developers Port Phillip and Westernport Catchment Management Authority Whittlesea City Council Hume City Council Industry Partners 3 Why Bother with Biodiversity in Urban Environments? Number and size of urban areas is increasing (~ 75% of the Australian population lives in urban settlements, will increase to 90% by 2011). Over 50% of threatened species occur in urban fringe areas. More than 80% of Aust species occur nowhere else in the world. (we ve had 17 mammal extinctions!) In Greater Melbourne, 32% of original vegetation remains. 96% of our grasslands have been destroyed! Have over 50 threatened fauna species. There are many good practical reasons for retaining biodiversity. 4 2

3 Our Goal What would an urban fringe landscape look like if we were serious about retaining our biodiversity? Develop a framework that can use ecological knowledge in conservation planning for urban development. Help determine where and how much area needs to be managed for biodiversity. 5 Conservation Planning Two core goals are conserving areas that are: Representative (where)- being able to represent the full range of biodiversity for a given region at all levels of organisation. Adequate (how much) conditions are met such that individual species, communities and ecosystems have a good chance of long-term survival. 6 3

4 Top-Down Approach Look at the landscape at larger scales Types of things to consider: Fraction of vegetation cover Spatial location and connectivity between habitat patches. Takes into account the spatial context of the landscape Assumes that species can disperse between patches 7 Bottom-Up Approach Use demographic models to calculate the minimum area required for a given species to persist. Simple models small data requirements apply to a larger number of species. Assume that all species are contained in a singe patch. (No spatial context) 8 4

5 Bottom-Up Approaches Min area will be very range widely for different species. It depends on: population density lifespan reproductive rates / variability sensitivity to environmental variability Large bird of prey ~ 100,000 ha Small ground dwelling mammal ~ 1,000 ha 9 Available Data Matt White, (Arthur Rylah Inst. for Environmental Research DSE) made first comprehensive series of maps for threatened species in greater Melbourne. Data based on models derived from expert opinion. Still don t have for non threatened species. 10 5

6 Black Falcon (Falco subniger) 11 Powerful Owl (Ninox strenua)

7 Where to now? Given this limited data what can we do? Flexible framework that can: Address the where and how much question. Capable of using different types of species habitat data (eg expert opinion, modelled, presence records). Combine top-down (spatial context) with bottom-up (persistence requirements). 13 Case Study Wyndham Growth Area Part of the sustainability assessment of development in growth corridors for Melbourne 2030 Work occurred in the middle

8 City of Wyndham (from: 15 Habitat map: Legless Lizard itserver.footscray.vic.edu.au/arcgras slands/lizards.htm Habitat map Good / Medium / Bad 16 8

9 Habitat map: Earless Dragon RAREAN/Var2921.htm Habitat map Good / Bad 17 Habitat Map: Growling Grass Frog frogs.org.au Habitat map Good / Medium / Bad 18 9

10 Case study Wyndham Growth Area Produced habitat maps (ARI) for 53 species Top-down approach using Zonation software to develop optimised landscape scenarios eats from the outside Maximise species, weighted by rarity Maximise habitat connectivity Minimise land cost Orange Bellied Parrot (Neophema chrysogaster) (from watts/3-3.htm) 19 Ranking of the whole landscape 20 10

11 Top 40% of landscape 21 Top 20% of landscape 22 11

12 Top 10% of landscape 23 Issues While it s important to identify priority areas for conservation, ranking the landscape can be dangerous. What fraction of areas should be saved for viable populations? Use bottom-up approach to determine minimum area requirements for a given species

13 Minimum Area Calculations Min Area (ha) Common Name Min Mean Max Black Falcon 23,094 31,623 42,426 Growling Grass Frog Striped Legless Lizard Grassland Earless Dragon 4,525 6,532 9, G Grass Frog habitat the overlaps with the top 40% of landscape

14 G Grass Frog largest remaining patch in top 40% of landscape. 27 Results Legless Lizard Earless Dragon Expansion Factor Fraction of landscape removed 28 14

15 Results G Grass Frog Black Falcon 8.00 Expansion Factor Fraction of landscape removed 29 Issues Need to consider larger spatial context habitat outside Wyndham. Only have maps for threatened species, not for common species. Consider temporal order of management actions. Resulting map only as good as input habitat maps. Method doesn t take into account extra threats (eg predation by cats) 30 15

16 Conclusions Started developing a framework that incorporates spatial context and quantitative persistence requirements. Can easily update method when new data becomes available. Some species in Wyndham aren t viable without revegetation. Plan to do a similar analysis in Hume and Whittlesea municipalities. 31 Thanks to Matt White Sarah Bekessy Michael Black Jo Morcombe Brendan Wintle Alex Lechner Industry Partners 32 16

17 Particular Issues for Urban Areas Complex range of competing land uses. Long term / large scale strategies are required. Urban landscapes are highly modified. Tools for cons planning and decision making designed for natural systems 33 Methods for determining Adequacy Population Viability Analysis. Intensive data requirements. Can only be done small number of species. Surrogate approaches Focal or umbrella species. Habitat availability Ecological thresholds 34 17

18 Allometric Relationships 35 Melbourne 2030 Strategic plan to manage growth and change across Melbourne Defines an urban growth boundary, green wedges and growth corridors Over the next 30 years: Pop will grow by 925,000 Av household size will fall from 2.6 to 2.25 persons 620,000 new households; 31% to be in greenfield locations Melbourne s green wedges and growth corridors (from

19 Dispersal Dispersal of species between patches won t be considered as first approximation For conservation areas surrounded by urban development this is a reasonable assumption for many species Birds are a special case? If other dispersal limited species (eg ground dwelling mammals) are made viable, then birds should be OK. 37 Zonation cell value calculations The value of each cell is given by the terms: qw Qc This is calculated for each species. q = quality factor, determined from species data, or other factors w = weight Q = rarity of species c = cost 38 19