Transcript Lecture 1
Urbanization and Wildlife Why do we care about urbanization? Urbanization • Rapid urban growth over the past ~50 years • By 2030, approximately 2/3 of humanity will be urban An Increasing Urban Population Interesting website: http://www.worldometers.info/ Why Are Urban Populations Increasing? • The world’s population is increasing • People are migrating to cities • Developed nations have higher percentage of urban residents than less developed Why are people migrating to cities? Urbanization: A Rising Tide (WRI 1996) Becoming More Urban Sprawling From Urban Centers Typical location of cities exaggerates impacts, why?: Typical location of cities exaggerates impacts: coasts, river mouths, lakes, fertile inland areas The World’s Urban Centers Tokyo > 34 million (greater metro); several others > 20 million (incl. NYC) Puget Trough Ecoregion (2) 8% of the land area of the state - contains over 70% of Washington's human population. Source: Seattle Audubon Society’s BirdWeb Urbanization isn’t just high rises and city centers… Houses/markets outside Nairobi, Kenya Urban Sprawl A form of urbanization distinguished by – Large areas of single-use development (residential) Heavy reliance on automobiles – Minimal public open space – Commercial strips – Low density Urban Sprawl: An Example 4% population increase drove 49% increase in developed land Urban Areas Have Large Ecological Footprints • Ecological Footprint: Amount of land and water area a human population requires to produce the resources it consumes and to absorb its wastes • A larger, more intensively used area is needed to support urban areas Urban Areas Have Large Ecological Footprints Urban footprints can be highly dispersed: Chicago’s famous pizza • Cheese from Wisconsin • Flour from Kansas • Oven from Japan or China Urban Areas Have Large Ecological Footprints What is this graph telling us? Urban Areas Have Large Ecological Footprints What is this graph telling us? Generating waste quicker than It can be turned back into Something useful. Using more resources than are renewable 23% too high Urban Areas Have Large Ecological Footprints How big is your footprint? http://www.footprintnetwork.org http://www.myfootprint.org/ 23% too high The Urban Gradient urban suburban exurban Shift in: • • • • Imperviousness (paved) Forest cover Exotic species Biodiversity wildland Species Biodiversity Why is the number of species detected lower in fully forested areas? Marzluff 2005 The Urban Gradient and Temperature Urban heat island Why is it hotter in cities? Urban Areas: Varying Effects on Wildlife Some benefits: • Reduced predation • Reduced climatic extremes • Available water • Supplemental food • New nest sites, living areas • Increased edge Some costs: • Increased predation • Reduction in nest sites (& other living areas) • Reduced food • New disturbances • Increased edge Vegetation amount and arrangement Vegetation structure and composition Food supply Photo: Joan Gellatly Nesting opportunities Suburban v Rural Eastern Screech Owls in Texas: Nested earlier (urban heat island) Larger clutches (more food) More and larger fledglings (food and low predation) More recruits into population Higher fitness Predators, competitors and disease! Feral Cats • ~77 million pet cats in US • Also millions of feral cats • Each year – Cats estimated to kill hundreds of millions of birds and small mammals* • Cats are a threat to urban biodiversity *American Bird Conservancy Controlling Urban Sprawl • Sprawl is a strong driver of the urban footprint – habitat loss/degradation, fragmentation – increases energy use – increases pollution (e.g. from commuting) • Growth Management is needed to control it – Limits most future growth inside Urban Growth Boundary – May just displace the problem if regional planning is not incorporated (leapfrogging) Growth Management Act - 1990 King County Comprehensive Plan Subdivision Planning Which plan is better for maintaining habitat? standard clustered Gillham (2002) Subdivision Planning Clustered subdivision: • Smaller lots • Higher density of homes • More open space standard clustered Gillham (2002) Wildlife Conservation in Urban Areas Preserve large areas of habitat The area, numbers, and connectivity of reserves should be maximized Buffers should be maintained around reserves The amount of edge and degree of fragmentation within reserves should be minimized Large scale (consider bioregions) Marzluff and Ewing (2001) Wildlife Conservation in Urban Areas Enhance habitat locally (backyard habitat) • Retain as much natural habitat as possible (especially new housing) • Plant native plants • Retain understory and snags • Minimize lawn cover Wildlife Conservation in Urban Areas Backyard Habitat Provide essential resources: • • • • Food (feeders, vegetation) Water Cover/shelter (vegetation) Place to raise young (nest boxes, etc.) Provide protection from domestic predators • Control dog and cat behavior Wildlife Conservation in Urban Areas Reduce accidental mortality: • Roadkill 1 million animals killed/day by cars; many in cities • Birds crashing into windows/hitting buildings, etc. 5+ million birds/yr • Disease from bird feeders (Salmonella) Wildlife Conservation in Urban Areas Support urban planning initiatives and education • Clustered development • Growth management • Open space preservation Community gardens • Local food • Shelter for wildlife • Organic (no chemicals) • Preserve open spaces • More permeable surfaces • Ecological and Environmental Ethic (stewardship) Community gardens PLUS: Many socio-economic benefits! Community Garden: Bronx Green-Up Transforms vacant, abandoned lots to community gardens http://www.nybg.org/green_up/comm_gard.php Community Garden: UW Farm Green Roofs Rockefeller Center • Provide wildlife habitat • Catch rainfall • Help lower urban temperatures • Decrease stress for humans http://www.greenroofs.org/ Chicago City Hall