This item is only available as the following downloads:
Improving Urban Ecology: Bringing Nature Back Home BY Leo Berman Ferretti A Thesis Submitted to the Division of Natural Sciences New College of Florida In partial fulfillment of the requirements for the degree Bachelor of Arts Under the sponsorship of Dr. Elzie McCord, Jr. Sarasota, Florida May 2011
iv Table of Contents LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 CHAPTER 1. FOSTERING URBAN ECOLOGY . . . . . . . . . . . . . . . . . . . . . . 3 B URGEONING B ENEFITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 P UBLIC P ROGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 O RGANIZED O UTREACH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 G REEN C ITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 W ANING W ATER : B EYOND W ELLS . . . . . . . . . . . . . . . . . . . . . . . . . . 12 R UNOFF R AMIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 H EAT I SLAND E FFECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 H ISTORY OF U RBAN N ATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 T RIUMPH FOR T REES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 F RUITLESS F AILURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 CHAPTER 2. METHODS FOR IMPROVING URBAN ECOSYSTEMS . . . . . . . . . . . . 24 R ESTORATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 R EFORESTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 U RBAN R ECONCILIATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 G REEN R OOFS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 CHAPTER 3. INHERENT IMPLICATIONS . . . . . . . . . . . . . . . . . . . . . . . 34 R EAL R OOF R ESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 C ASE 1: J EAN V OLLUM N ATURAL C APITAL C ENTER . . . . . . . . . . . . . . . . . . . 34 D ISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V ERDANT V ERDICT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
v List of Figures Figure 1. This map depicts global water stress without water management. Reprinted from (Black 2010). . . . . . . . . . . . . . . . . . . . . . . 13 Figure 2. This map depicts water stress predictions after water management practices have been utilized. Reprinted from (Black 2010) . . . . . . . . . . . 13 Figure 3. Percent Runoff as a function of percent impervious area. Reprinted from (Korhnak 2001) . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 4. Runoff attenuation efficiency for a .04-inch rainfall event on a green roof with saturated media. Reprinted from ([USEPA] 2010) . . . . . . . . 16 Figure 5. Rainwater runoff retention of green roof test plot in Ottawa, Ontario, Canada in 2002 compared to an adjacent conventional roof of the same size. Values are sums of total runoff. The green roof was fitted with 15cm of growing medium and planted with lawn grasses. Reprinted from (Oberndorfer 2007). 17 Figure 6. The basic green roof design. Taken from (Remer 2011), (Image Copyright American Wick Drain Corporation). . . . . . . . . . . . . . . . 27 Figure 7. An extensive green roof on a tall building in a city, taken from (Brooklyn Feed 2011) . . . . . . . . . . . . . . . . . . . . . . . . . 28 Figure 8. Vegetable and herb garden atop the Fairmount York Hotel, Toronto. Taken from (King 2008). . . . . . . . . . . . . . . . . . . . . . . . 29 Figure 9. Types of extensive green roofing techniques: (a) Complete system: Every part of the setup is installed as an "integral part of the roof. (b) Modular system: pre-cultivated vegetation trays are installed above existing roof. (c) Precultivated vegetation blankets: growth medium, drainage mats, root barrier, waterproofing membrane and plants are rolled onto existing roof. Taken from (Oberndorfer 2007). Graphics by Jeremy Lundholm . . . . . . . . . . 32 Figure 10. An intensive green roof with trees and bushes atop the Solaire building in Battery Park City in New York. Taken from (Remer 2011) (Photo Copyright birdw0rks/Simon Bird and the Albanese Organization.) . . . . . . . . 33 Figure 11. Species used on the Natural Capital Center, Portland, Oregon. Taken from (Paladino, 2004). . . . . . . . . . . . . . . . . . . . . . . . 35
vi Acknowledgements I thank my parents for their encouragement and support throughout my life. I have no doubt that growing up close to nature has helped me find my calling in environmental science. I am grateful for all your love and time and providing me with the opportunity to attend New College. I also thank my brother, Max, for always being there, helping, encouraging me to go further and helping me edit my thesis. I thank Leandra for being an encouraging partneryou got me to write this thing early! Thanks to my Professors: Dr. Elzie McCord, Dr. Alfred Beulig, and Dr. Diana Weber for your help in editing and bringing out my ideas, you were instrumental to the completion of my thesis. Thank you Thomas Slabe you're your time talking with me about green roofs and reviewing my thesis was tremendously beneficial. Thanks Meg Lowman for leading an ISP into the Amazon and getting me started on my Environmental track. Finally, thanks to all of my friends who have stuck by me as we have all grown and wrote theses.
vii Improving Urban Ecology: Bringing Nature Back Home Leo Berman Ferretti Abstract The urban environment is the new frontier for ecological improvement. Urban planting creates a richer ecosystem, enhances biodiversity, improves mental health, and alleviates some of the environmental externalities generated by urban areas (including pollution, runoff and heat island effects). This thesis examines the importance of improving city ecology and explores strategies by which to enact these improvements. Today, new measures-such as restoration, reforestation, reconciliation and building green roofs-must be taken to foster urban biodiversity. Developers often overlook the advantages of well-rounded planting programs due to their cost, but education can reverse this trend. Urban environmental research suggests that the benefits of urban greening far outweigh the costs. Elzie McCord, Jr., Ph.D Division of Natural Sciences
viii Introduction When considering where to find vibrant ecosystems teeming with plants and animals, cities might be the last place you think of. Cities are full of concrete, cars and people; they are completely unsympathetic to wildlifeor so we have been led to believe. How much of our perceptions is myth and how much is reality? Can our increasingly urban civilization learn the benefits of incorporating flora and fauna? My thesis explores these possibilities by compiling research on the advantages of plant life provides to human and ecosystem well-being. With proper incentives, cities in America could be transformed from a collection of concrete monoliths into verdant greenscapes that improve the environment while being healthier places to live. The first chapter makes the case for urban planting programs and examines strategies by which these programs might be enacted. Like any major public policy initiative, an overhaul of our urban areas will require the kind of political will that can only be generated through a vigorous campaign of public education and advocacy. In the next chapter, methods for improving urban ecosystems are explored. A combination of techniques, from traditional restoration to the broad field of urban reconciliation, is needed to tackle this challenge. The planting of green roofs, in particular, appears to be an ideal strategy.
2 The final chapter compiles the research into a coherent argument for the need to improve urban vegetation. Cities are the most important areas to change, though every backyard or empty field can be used. Native plants must replace the traditional water-intensive monocultures of manicured lawns in American suburbia. Small changes can snowball into a new mindset for urbanites.
3 Chapter 1. Fostering Urban Ecology Humans are not so different from their wild neighbors: every animal, from insects to cougars, needs a little land to claim as home. Given the scarcity of habitats amenable to urban development (ones in which water, food and temperate weather are available), it is not surprising that the expansion of human settlements has resulted in unprecedented competition with critical species for their prime habitats. Unlike other competitors throughout evolutionary history, when humans populate an area habitats become fragmented and degraded by pollution, buildings, and concrete infrastructure. An example of human development fragmenting habitat can be seen in Florida. Florida hosts a large variety of species, which are endemic to certain parts of the state (e.g., Florida scrub is limited mostly to Pinellas County). The urban environment, in conjunction with urban sprawl, fragments these unique habitats by dividing the land into smaller parcels. Habitat fragmentation of unique ecosystems 1 (such as Florida scrub or the Everglades) may limit the ability of a native species to maintain sufficient genetic variability (Stiling 2002). Without intervention, loss of genetic variability can harm individual populations, leading ecosystems to collapse (Stiling 2002). This is especially true of keystone species. Keystone species is a term originally coined by Paine (1966) and defined as a species of high trophic significance whose activities have a disproportionate influence on the pattern of species diversity in a community. Though this definition has been argued to be too stringent and some ecologists argue that a 1 Ecosystems found in very few places around the world
4 keystone species is any species that has a large effect on any aspect of an ecosystem (Payton and Fenner 2002). The effects of such a collapse could ripple through other ecosystems harming human and wildlife health. Humans are already seeing a drastic example of this kind of chain reaction in honeybee colony collapse disorder, which has impacted food production and threatens plant species (Ellis 2011). Naturalist and author Richard Mabey suggests that modern large-scale eradication of weeds and native flora could be partly to blame for bee decline (McFarlane 2010). Weeds play an overlooked role in nature, providing an important source of nectar and pollen, especially when crops are not present (McFarlane 2010). Thus, an act as simple as removing weeds can have dramatic effects on ecosystem users. Reducing wild plant populations harms biodiversity, which is the array of various plant and animal species that make up a community or ecosystem. It is difficult to convince people to encourage native plant growth when many do not understand what biodiversity is (BBC 2010b). Once residents understand the importance of maintaining ecosystems and the benefits to them, they may be willing to share their land to promote a healthier urban ecosystem. Burgeoning Benefits Incorporating natural elements into urban landscape improves human wellbeing in many ways. Costanza et al (1997) estimated the value of the world's ecosystems at 16-54 trillion USD (10 12 ) per year with an average of 33 trillion USD per year by measuring and estimating the value of processes performed by
5 ecosystems around the world. The ecosystem value calculations are low estimates and not inclusive (Costanza et al. 1997). The estimated values include environmental functions such as plant regulation of atmospheric gases, wetland filtration of water and waste decomposition, recreation areas provided by parks, and myriad other services (Costanza et al. 1997). The world's ecosystems are also self-maintaining. Preserving and improving environmental conditions is, therefore, a valuable economic endeavor. The value of the ecological functions performed by vegetated areas more than compensates for the cost of planting and maintaing them. Increased planting, the planting of native plants in particular, should be a priority. Once a native restoration area is established, it can sustain itself with little to no maintenance because the plants are already adapted to the climate and ecosystem. Vegetation in conjunction with landscape design increases property value and may pay back the initial restoration cost. Employing knowledge of "green" benefits can improve the areas where humans live and work. For example, increasing the foliage outside a laboratory or hospital may increase the efficiency of technicians and doctors (Miller 2005). Exposure to natural elements also appears to encourage more effective functioning from tired individuals. A study analyzing the relationship between window view and recovery time at six hospitals showed a faster recovery time for patients whose window overlooks a natural setting (Kaplan and Kaplan 1989). Additionally, use of health services by prisoners in relation to window view suggests that those with the most natural views require the least health care (Kaplan and Kaplan 1989). This is
6 significant because in 2009, North Carolina spent over $230 Million on prisoner healthcare, perhaps with greener views, costs would be reduced (Smith 2010). Vegetation is known to absorb pollutants, nutrients and sometimes heavy metals. The urban environment is the perfect place for such a filter. Incorporating green roofs into cities has been shown to significantly reduce airborne pollutantsa major cause of respiratory disease (Yang, Yu, Gong 2008). Viewing natural scenes, such as green roofs, speeds up recovery from stress and provides a more thorough recuperation than viewing an urban or man-made environment (Ulrich and others 1991). Integrating wildlife habitat may relieve over-stressed university students, produce more effective office workers (Miller 2005) and save money at hospitals by reducing recovery time (Kaplan and Kaplan 1989). Overall a greener city correlates to a healthier population and less expenditure on health care. Natural areas have positive effects on the human psyche (Kaplan and Kaplan 1989) and health. A new study shows that as few as five minutes of exercise in a green setting (especially one containing water) per day improves mental health, (BBC 2010). Architects can utilize this to create "happy areas" for people suffering from depression or other mental disorders. Green areas may even prevent some ailments. Additional research has shown that there is a "biophilic" response in humans when exposed to natural areas; an innate pleasure response is activated when a person is surrounded by nature (Miller 2005). Biophilia is the love of connecting with nature or seeing a natural area (Kellert and Wilson 1993). Being in the presence of natural elements also appears to encourage high-order cognitive functioning, enhanced observational skills and improved reasoning (Miller 2005).
7 Urban greening has positive effects on the environment as well. Vertical green space 2 leads to richer biodiversity and better nutrient and water cycle (Lowman and Rinker 2004). When monoculture grass lawns, paved roads or buildings replace a complex ecosystem, much of the hydrological cycle and habitable area degrades. The introduction of impervious surfaces (such as asphalt or concrete) increases rainwater runoff by making the ground less effective at absorbing water from heavy precipitation. Trees normally absorb the kinetic power of rain and retain soil with their roots. Without plants and healthy soil, small storms can mean significant runoff, flooding, and erosion (Korhnak 2001). Both live and dead matter along a forest floor hold soil and lock in precious water. In forests, runoff is generally minute since plants decrease through-fall 3 (Lowman and Rinker 2004) as it passes through various levels of the canopy, filling epiphytic phytotelmata, wetting mosses, etc. and then seeps deep into the organic debris and ground (Korhnak 2001). Runoff becomes a major concern as areas of complex vegetation are replaced with impervious surfaces, which channel precipitation into drains as runoff. Public Programs The multi-faceted benefits of urban greening are hard to ignore unless they are unknown. The public must be closely involved in order to change the social atmosphere with regard to vegetation in cities. Planting native flora on private 2 Vertical green space is more complex than grass and provides more habitat for wildlife 3 A ratio of the amount of water reaching the ground compared to the amount that falls
8 property, around religious centers and government buildings are a few simple first steps towards a more sustainable civilization. Hosting adopt-a-plant events is a great way to encourage people to support the initiative. Local governments can purchase native seedlings and give them to homeowners to plant in their yards. Individual landowners and renters who transform their properties into more sustainable areas, rich in biodiversity could be rewarded. Rewards could be in the form of tax cuts, free solar panels or another incentive. Eventually the government could transition from incentive based cooperation to enacting laws that would require landowners to plant native flora or build a green roof when replacing an old one. Instituting more rigorous efficiency codes would also foster a more sustainable urban environment. The German government has done just this with their green roof initiative, which is explained later (Oberndorfer 2007). Policy is not a stand-alone solution; a project to change the urban world requires public support. The many benefits of urban ecological remediation can help convince the public to make changes. It is essential to reach the general populace and convince them that ecological consideration benefits individuals along with the local and global ecology (Khler 2002; Oberndorfer 2007). Creating viable habitat for wildlife requires community support. Local community leaders, from homeowners associations to spiritual leaders, can take steps to support local ecosystems. Organized Outreach Outreach programs, especially for children, are imperative to raise awareness of the importance of preserving nature. Increasing exposure to nature at a young age
9 can improve the likelihood of a person taking action to preserve native habitat (Bixler, Floyd, Hammitt 2002). Providing safe natural areas for children to play may help support the future of environmental initiatives (Miller 2005). A study by Bixler (2002) found that children, who played in a wildland setting, were more concerned about the health of the environment and preferred to protect it. A severe decline in environmental expectations as well as an increase in apathy towards the environment is observed in young children who do not interact with a natural area (Pauly 1995). The world is not static, it is constantly changing and evolving, which makes environmental degradation difficult to recognize in a single lifetime. The Shifting Baseline Syndrome (SBS) is a challenge only education can meet. SBS is where each generation sees a slight degradation of the environment throughout their life, which constitutes only a fraction of the total long-term degradation (Miller 2005). With each generation, the baseline of a healthy environment is lower than that of the previous. Educating people now can elucidate the true severity of environmental decline before it is too late to change. Plants that are endangered could hold vital medicinal and food value. Recently, the common weed, Petty spurge, Euphorbia peplus L. in the UK was found to effectively treat skin cancers, including basal cell carcinoma and squamous cell carcinoma (Roberts 2011). Shukman (2010) also suggests that humans have become too dependent on a narrow range of plants. Eighty percent of calories consumed globally are harvested from only 12 different plant species. An outbreak of a virus or insect able to decimate one of these crucial species could be catastrophic globally. It is therefore necessary to transform every available patch of land in an urban
10 environment into viable habitatto encourage biodiversity in backyards, medians, public parks, university campuses and especially rooftops. Food diversity should be increased to thwart the potential for a global famine. A hardy, virus-resistant plant evolving on a green roof could hold the key to stopping viruses that effect other plants in the future. Green Cities Cities are the most important frontier when we consider how to provide the new habitable area required by natural systems. By convincing the public that humans and society are still a part of nature, it will become more feasible for urban areas to include both extensive development and biodiversity. Ignoring the need for environmental improvement in cities is both unwise and dangerous to local flora, fauna and humans. As vegetation decreases in the urban environment, peak storm runoff increases and requires more drainage infrastructure. Larger cities increase the risk of flash floods as miles of rainwater is concentrated into smaller storm drains, which erode streambeds and riparian ecosystems (Walsh, Fletcher, Ladson 2005). About 50 percent of the world's population now lives in cities and the percentage is growing (Evans 2002). As more people aggregate towards cities, they will become more important as an ecological niche. Expanding urbanization across the earth begs the questionwhere are the animals going? As Rosenzweig points out, humans must share land with wildlife to preserve biodiversity. The species-area relationships (SPARs), expresses the positive correlation between habitat area and number of species (Rosenzweig and Ziv 1999; Rosenzweig 2003). This relationship
11 has been observed globally in plants and animals as well as islands and continents. It was formalized into a power equation by ecologists from the 1920's-1960's: S = CAz (1) where S is the number of species, A is the area, and C and z are constants. For convenience, ecologists generally employ the logarithmic form of this equation: log S=c+z log A (2) where c=log C. (Arrhenius 1921; Preston 1960; Rosenzweig and Ziv 1999; Rosenzweig 2003). The implication of this relationship is an environment in much more dire straits than the general public believes and most ecological models suggest. As viable habitat is reduced, species diversity reduces exponentially. Small preserves and refuges, which consist of a small percentage of total landmass, are not enough (Rosenzweig 2003). Large areas populated by humans must also accommodate native flora and fauna; otherwise diversity will be reduced as less land is set aside for them (Rosenzweig 2003). Shukman (2010) conducted a worldwide study, which showed that 22% of plants sampled were threatenedabout the same percentage as mammals. Thirty-three (33%) of the plants sampled were so unfamiliar that researchers from the Royal Botanic Gardens at Kew, the Natural History Museum, London and International Union for the Conservation of Nature (IUCN) were unsure of how to assess them ecologically (Shukman 2010). While the importance of flora in ecosystems is undeniable, protecting plant diversity is also vital to human health. Luckily, making changes to the urban environment can be beneficial to humans and animals. If a city has the resources to perform a restoration or reforestation project they should restore and protect based on the benefits previously outlined. If
12 resources are limited, scattering as many vegetated corridors as possible throughout the city will provide mobile wildlife with ways to flourish. Waning Water: Beyond Wells Runoff has to be conserved as a source of water as the world's climate becomes more unpredictable. Shrinking aquifers, sporadic precipitation and lowering water tables threaten many land-bound organisms. It is important to keep freshwater in the ground otherwise there is risk of saltwater intrusion into the groundwater. When too much freshwater is lost from underground sources, the pressure of saltwater can push inward, permanently contaminating the source (Todd 1960). Researchers have analyzed water management decisions and their consequences in developed nations such as the United States and Europe. Currently, management has been modeled for human use without much consideration for wildlife (Black 2010). Approximately 80% of the world's population, along with local wildlife, is threatened by diminishing fresh water supplies (Black 2010). Developed countries treat the symptoms instead of remediating natural hydrological functions, while developing countries lack the means to remediate (Vorosmarty and others 2010). Vorosmarty et al. (2010) suggests the most cost effective and reliable longterm way to manage water is to account for all users: plants, wildlife and humans. Preventing pollution, runoff, fertilizers, etc. from entering the water makes expensive treatment plants unnecessary. The IUCN suggests using more natural techniques to clean water such as preserving wetlands, floodplains and existing streams instead of
13 "concrete and steel" methods (Black 2010). Figures 1 and 2 show freshwater scarcity maps, before and after management. Many developing countries, i.e., much of Africa, do not have favorable outcomes. Africa will be worse off likely because Asia will divert and dam rivers to manage water, leaving little to reach Africa. Figure 1. This map depicts global water stress without water management. Reprinted from (Black 2010). Figure 2. This map depicts water stress predictions after water management practices have been utilized. Reprinted from (Black 2010) Water shortage is a major hindrance to humans as well as native flora and fauna. Inclusive plans for water management that treat problems at the source are
14 beneficial to all life forms. Case in point: the New York City water supply crisis of the 1990's. Agricultural pollution threatened the quality of the city's water. New York had to choose between building water filtration plants or protecting their water at the source (Warren 2003). A cost-benefit analysis led the city to invest in land protection and conservation, which maintained water quality. This strategy was cheaper than treatment plants and improved local biodiversity (Black 2010). Runoff Ramifications Maintaining the hydrological cycle of ecosystems in areas prone to consistent storm frequency and/or periodic flash storms should be a top priority to prevent flooding, erosion and water loss. Water should be retained quickly in coastal regions because once runoff enters saltwater its evaporation rate is decreased through its bond to salt (Hornback 2006). The salt creates ionic charges and the added bond strength decreases the vapor pressure and the rate of evaporation. When the option is available, collecting rainwater is much more efficient than later desalinating ocean water. Freshwater is becoming more valuable and needs to be protected from waste. Figure 3 represents how strongly correlated runoff is to the amount of impervious ground cover. Using this information, developers can reduce the amount of runoff by leaving green spaces and forested ecosystems intact near human communities (Mentens 2006). Additionally, retention ponds and rooftop gardens can help offset necessary impervious surfaces (Bass, Liu, Baskaran 2003; Oberndorfer 2007).
15 Figure 3. Percent Runoff as a function of percent impervious area. Reprinted from (Korhnak 2001) Runoff carries away valuable water along with artifacts of the urban environment: fertilizers, pesticides, and other chemicals found around humans. An example of the human impact on waterways is the correlation between eutrophication 4 in the Great Lakes and human population density (Stiling 2002). A bloom of dinoflagellates or other microorganisms such as cyanobacteria or algae, can cause massive extinctions of aquatic species such as the infamous red-tide 5 (NOAA 2011). Runoff from agriculture is one of the biggest contributors to eutrophication of waterways. Higher nutrient levels promote the growth of algae and subsequently microorganisms, which results in loss of clean water, degradation of waterways and overall reduction of the ecological richness of an area (Korhnak 2001). 4 Eutrophication is an increase in nutrients causing an algae bloom and plant growth, which sequesters carbon and causes oxygen deficit (NOAA 2011). 5 Red-tide is a water discoloration and massive fish kill caused by microorganisms such as algae, cyanobacteria or dinoflagellates which created an oxygen deficit. (NOAA 2011)
16 Reducing peak runoff reduces the load on sewer systems, mitigates flooding, and alleviates the health hazards of standing water. A quarter inch of rain across miles of efficient cement "aqueducts" funneling into municipal sewage treatment creates too much water to capture. When green roofs are introduced, see figure 4, water continues to flow off the green roof after rain has stopped falling, but it holds onto water long enough to disperse it. As shown in figure 4, the highest rainfall peaks are no longer directly correlated with the highest runoff peaks. Figure 4. Runoff attenuation efficiency for a .04-inch rainfall event on a green roof with saturated media. Reprinted from ([USEPA] 2010) Figure 5 shows the reduction of runoff that can be realized through green roofs compared to conventional roofs. Green roofs are most effective when they are unsaturated and absorbing a slow rainfall. Figure 5 shows that June had the highest
17 seasonal precipitation and green roofs effectively reduced runoff, even during peak rain season. Figure 5. Rainwater runoff retention of green roof test plot in Ottawa, Ontario, Canada in 2002 compared to an adjacent conventional roof of the same size. Values are sums of total runoff. The green roof was fitted with 15cm of growing medium and planted with lawn grasses. Reprinted from (Oberndorfer 2007). Heat Island Effect Cities cause more than water issues, they can also alter their local climates (McPherson et al. 1994). In concrete jungles, the urban heat island effect is readily apparent. Coder (2001) finds that urban areas average 0.8 ¡ C hotter annually than natural areas. A way to counteract this effect is to increase greenery and shade by planting large-growing trees (such as oaks) when possible and covering surfaces with greenery, i.e., rooftop gardens. According to research, extensive tree cover can reduce local air temperature by 0.6¡ to 5¡ C (McPherson et al. 1994).
18 Vegetation also decreases the albedo effect 6 In the UVB region ( < 315 nm) 7 the measured albedo is between 0.0160.017 over vegetation compared to 0.07-0.10 over concrete (Feister and Grewe 1995). The higher reflective potential of concrete in cities (five to six times that of vegetation) causes solar radiation to bounce from surface to surface leading to the heat-island effect (Khler 2002). Vegetation absorbs solar energy and then disperses it through transpiration 8 History of Urban Nature Flora, and in turn fauna, have been incorporated into civilization throughout human history. The move to push plants out of cities is a modern postindustrialization zeitgeist 9 One of the first well-documented elevated gardens was the famous hanging garden of Semiramis from the early 600's BCE (Oberndorfer 2007). Research in some Chinese cities that have been documented for the past 2800 years, such as Guangzhou, show some the importance of setting aside contiguous areas for trees in urban design. Tree occurrence, density and species diversity are dependent on developmental history, density of human population and land use (Jim and Liu 2001). Guangzhou was the oldest city studied and it now has relatively compact buildings and roads pushing natural areas out of the urban centers. Guangzhou had a history of urban forestry until the late 1900's when an economic boom caused development in many areas formerly set aside for trees. 6 Albedo is the ratio between solar radiation (UV and visible) and the radiation reflected back from surfaces. 7 Measure of wavelength 8 Transpirationheat removed by water released from plant leaves 9 Zeitgeist"spirit of the times" means the cultural, ethical, political, etc. climate within a nation or the world.
19 Newer cities should learn to plan effectively to preserve trees. Planning includes creating specialized corridors to cater to native species and observing migration patterns in relation to city layout to determine the best location for stepping-stones of vegetation (Tischendorf 2000). If areas are not designated for greenery in a growing metropolis, interpenetration of trees will be severely reduced along with the ecological function of remaining vegetation (Jim and Liu 2001; Tischendorf 2000). Cities in the United States are often viewed as disconnected from nature, however they are still susceptible to nature's overpopulation remedies: diseases, pests and fires. In natural settings, whenever one species grows too large in population, there is a balancing mechanism. Populations can be controlled by anything from a microscopic virus to a top predator made of millions of cells. Historian Diane Galusha describes a time in the late 1700's when all of the water for New York City came from a pond called the Collect,' which was also the dump for trash and dead animals (Abumrad and Krulwich 2010). The lack of hygiene, water filtration and proper trash disposal transformed the streets and waterways into breeding grounds for disease. People began getting sick with a yellow fever outbreak in 1798 and typhoid fever throughout early 1900's (Warren 2003). In 1832, cholera began spreading viciously across the country; cities were the hardest hit, but the outbreaks spread to rural America as well. Cholera reappeared from 1849-1854 and again in 1866, truly terrorizing the nation (Warren 2003). Overpopulation, lack of clean water and waste disposal perpetuated disease and disorder until people built the infrastructure to move clean water and treat sewage.
20 Cities are alive, says Geoffrey West, theoretical physicist (Abumrad and Krulwich 2010). Cities have a metabolism. Energy, ideas, water, food and people go in while heat, chemicals, sewage, products and waste goes out (Abumrad and Krulwich 2010). Cities even have the natural balancing mechanisms you find in any population in the wild. Cities adapt to overcome bacteria, disease and fire just as the mechanisms adapt to continue to subdue civilization. Fires are a natural and beneficial part of many ecosystems, but they are always destructive (and sometimes catastrophic) especially for predominantly dry wooden cities. In December of 1835 a New York building caught fire but the only water supply, the river, was frozenthe Fire Department could do nothing and 700 buildings burned (Abumrad and Krulwich 2010). The city adapted to the threat of sickness and fire by drilling an underground tunnel to secure fresh water from Catskill reservoirs and aquifers. In October 1842 the first water tunnel temporarily quenched the growing thirst of the city but an expanding, living city continues to demand a greater water supply says Galusha (Abumrad and Krulwich 2010). As cities continue to grow, they will require more land and resources, leaving less available for native flora and fauna. Triumph for Trees In the US, several great successes for the environment have come from the government. The first was the National Parks Act of 1916, which created a separate government agency (National Park Service) to control national parks (Warren 2003). Then in 1964, the Wilderness Act was passed which allowed the designation of
21 wilderness areas on federal land (Warren 2003). The next big success was the passage of the National Environmental Policy Act (NEPA) of 1969. It required all new government programs to include an Environmental Impact Statement (EIS), which still has far reaching effects today (Warren 2003). The creation of Earth Day in 1970 is another marker of the change in values for America. Increasing numbers of people wanted to ensure the protection of the American wildlands, and this led to a doubling in membership of The Wilderness Society, the Sierra Club and the National Audubon Society by the end of the 1960's (Warren 2003). More recent successes for the urban environment have been achieved by forward thinking businesses such as Ford. The roof of the Ford Dearborn, Michigan assembly plant holds one of the largest green roofs in the world, measuring 42,900 m 2 Vegetation consists of 13 Sedum species on a 7.6 cm medium. It hosts 29 insect, seven spider and two bird species after only two years (Getter and Rowe 2006). This is a marked change from a blazing hot roof that hosted almost no life previously. Many developed countries, especially in Europe, have begun to make positive changes for a more sustainable urban environment. Germany is a great example of successful environmental work. Green roofing projects in Germany are rapidly expanding due to support from the people and businesses that benefit from them. German law now requires the construction of green roofs in many urban centers (Oberndorfer 2007). Legal framework supporting green roof construction has been beneficial in widespread implementation of the technology. Switzerland has also seen the merit of green roofs and has mandated them on all new flat roofs (Brenneisen 2006). Green roofs provide protected habitat for
22 endangered species because many are inaccessible to large mammals. Studies on green roofs in Switzerland have shown this on both new and old green roofs. In Basel, Switzerland a biodiversity survey on 17 three-year old green roofs found 78 spider and 254 beetle species. Eighteen percent of the spiders and 11% of the beetles were either rare or endangered (Brenneisen 2006; Getter and Rowe 2006). Some of the Swiss green roofs use local soil as the growing medium and specific roofs cater to specific endangered species. In another paper by Brenneisen, he finds nine orchid species and a variety of rare or endangered plant species on a 90-year-old green roof in northeast Switzerland (Brenneisen 2003). Additionally, many birds have been observed using green roofs in Germany, Switzerland and England (Getter and Rowe 2006). Fruitless Failures With the positives of the environmental movement came the backlashthe anti-environmentalists. President Reagan, a staunch anti-environmentalist, appointed prominent anti-environmentalist and lawyer, James Watt as Secretary of Interior, steward of national parks in 1980 (Warren 2003). Reagan also removed the solar panels from the Whitehouse that President Carter installed (James 2010). Reagan claimed that trees cause more pollution than automobiles and thus justified increased logging of forests (Warren 2003). While it is true that trees release various gases and chemicals they cannot be classified as pollution since they shape the gas balance of the biosphere. His leadership led to a reduction in quality and funding for the national parks and a pause for government-led environmental initiatives. The anti-
23 environmentalist ideas have faded and in 201l President Obama is installing solar panels atop the Whitehouse once more to lead the country through example. There are still difficulties in moving towards a more sustainable urban environment regardless of intentions. Green roofs, though seeming to perfectly fill an unoccupied niche in the urban environment may be unsuccessful due to climactic conditions or poor plant and growth media choices. One such example is one of the first green roofs constructed in Portland, Oregon. The companyGerding Edlen Development, was in the process of building six LEED Certified buildings (Schneider 2009) (LEED is a classification of environmentally sustainable buildings). After installing vegetated Sedum coverage on a flat roof with organic soil, many plants died. Poor drainage led to perennial ponding in sections of the roof, soil rich in organic matter and standing water are both detrimental to the Sedum genus, which prefers rocky-gravel with good drainage ([USEPA] 2010 ). The Sedum cover mostly died due to an unsuitable environment since the species used were successful in England. Wind-blown seeds did grow on the roof, which shows that native plants should be used whenever possible and the green roof should cater to them (Schneider 2009).
24 Chapter 2. Methods for Improving Urban Ecosystems There are a variety of methods for urban wildlife habitat improvement, though the first step is the same. Site assessment of an area will determine how much remediation is needed and in which areas i.e., soil aeration, hydrological function improvement or removal of invasive species. In assessing a site, factors to look at are: human-caused changes, site history, presence of toxins or fertilizers, soil quality, climate, topography, energy balance, water balance, genetic diversity and the actual land area available to work with (Coder 2001). Each factor has a vital role in building a healthy community. The extent of damage from humans, invasive species or erosion determines the correct program for a particular parcel of land. Restoration Ecological restoration focuses on protecting animals, preserving plant diversity and reintroducing simulated habitat. In 1992, the National Research Council defined ecological restoration as "The return of an ecosystem to a close approximation of its condition prior to disturbance" (Duryea 2001). Complete ecological restoration is usually not possible because of the extreme changes humans have made to the environment, specifically in urban areas 1 0 For a restoration to be effective, a large area of land needs to be protected from disturbance. People are generally reluctant to part with large parcels of land if they see it as "wasted" on natural functions. Since humans can not utilize the restored land besides some 1 0 Replacing soil with impermeable asphalt or concrete reduces plant recruitment efficacy
25 limited eco-tourism, the expense to create and maintain them may outweigh the benefits in suburban America. Despite these challenges, restoration can be beneficial, especially when trying to protect an endangered species. An area can be restored to a species' natural habitat to promote a larger population. It is usually not practical to undergo such an endeavor in or near an urban setting. The amount of land required for a viable population of most species would be too cost-prohibitive. There must be enough land to maintain every trophic level of the ecosystem from plant to top predator (Stiling 2002). Reforestation Reforestation creates new, forested habitat that does not necessarily reflect original conditions. Changes in the environment make remaining vegetation crucial to wildlife still clinging to survival. Remaining vegetation patches in urban areas can maintain metapopulations of flora and fauna and serve as stepping-stones or corridors for mobile wildlife (Ruiz-Jan and Aide 2006). Corridors can help maximize biodiversity by broadening the gene pool of mobile species. Planting native trees and plants is more important than previously thoughtone fifth (20%) of the plant species globally are at risk of extinction due to habitat loss and climate changes (Shukman 2010). Plants, unlike animals, cannot move away from development, they are overrun and plowed. Increasing planting and vertical stratification is a space efficient way to accommodate more species in a smaller area. Vertical stratification is having different plants at each height: ground cover, shrubs, small trees and large trees. According to
26 Lowman (2004) between 50-80 % of biota can be found above the ground in the Amazon Rainforest. More vertical green space leads to richer biodiversity and better nutrient and water cycle flow, which benefit a broad range of species. Additionally, creating a more complex vegetation structure promotes colonization of more plant species and alters the microhabitat of the area (Ruiz-Jan and Aide 2006). Reforestation is feasible when open land is available. Abandoned property can be utilized for environmental reforestation with the cost of such projects depending on how quickly trees are desired. The lowest cost, longest time solution is to do nothing and wait for native plants to grow (add temporal scale at end), though this in itself has inherent risks, such as invasive species taking a foothold. The slightly faster, but still low cost, solution is direct seeding of the plants desired. The fastest, most work and cost-intensive method is transplanting trees of varying sizes. However, this solution requires labor to move the trees and plant them and some irrigation to prevent shock. Urban Reconciliation "Urban Reconciliation," coined by Michael L. Rosenzweig, is a broad field that aims to build a shared landscape to reconcile land demands of natural systems and human populations (Rosenzweig 2003). In contrast with the aforementioned techniques, reconciliation takes a compromising approach. Recognizing that human culture in urban environments has permanently altered the previous ecosystems; it attempts to mitigate the effects on endemic flora and fauna while benefiting local human populations. Reconciliation ecology is defined as: "redesigning anthropogenic habitats so that their use is compatible with use by a broad array of other species"
27 (Rosenzweig 2003). Native flora and fauna must be considered in urban planning as urbanization spreads across the world. A single 7.6-meter tree growing near a home can reduce annual temperature control costs by 8-12 % (equating to an average of $10-25) (McPherson and Rowntree 1993). Assuming $10 per house, a national treeplanting program could save $1 billion in electricity per year with just one tree per house. Green Roofs Figure 6. The basic green roof design. Taken from (Remer 2011), (Image Copyright American Wick Drain Corporation). Green roofs are a great example of a method of reconciliation ecology: they are aesthetically pleasing, economical, reduce the heat island effect (Worden and
28 others 2004), and make a significant improvement in area water retention and filtration (Bass, Liu, Baskaran 2003). Green roofing is the equivalent of pushing the ground level flora and fauna up 10, 20, or 100 feet. Since roofs consist of around 32% of horizontal surfaces in developed areas, they present the perfect starting place for re-introducing local flora and attracting wildlife (Oberndorfer 2007). Figure 7. An extensive green roof on a tall building in a city, taken from (Brooklyn Feed 2011) Strong buildings can host small parks and personal homes can host small gardens or grasses for environmental benefits. Though it may be a more expensive initial investment than a standard roof, homeowners may receive funding from the Environmental Protection Agency's Clean Water Act Section 319 (non-point source pollution) grant program (Worden and others 2004), through local environmental
29 funds or from cities 1 1 (Stutz 2010). Vegetated rooftops can also subsidize themselves by growing some vegetables (Oberndorfer 2007). Figure 8. Vegetable and herb garden atop the Fairmount York Hotel, Toronto. Taken from (King 2008). A costbenefit analysis further supports a vegetated roof. One obtains an aesthetically pleasing roof, an extra 20 or more years of roof-life, fireproofing 1 2 thermal and sound insulation (Oberndorfer 2007), habitat for insects and small animals vital to a healthy ecosystem, and even some government subsidies to reduce the cost (Worden 2004; [USEPA] 2010). In Germany, green-roofing companies are so sure of the quality that they warrant green roofs for 30 years (Khler 2002). 1 1 Portland, Oregon provides $5/ft 2 for green roofs 1 2 Fireproof roofs protect from wind-blown embers, especially valuable for someone on the wildland-urban interface.
30 There are two main types of green roofs; the easier and cheaper type is called extensive (Figure 9). It includes a high porosity substrate depth of 2-20cm, lightweight system (typically an additional 70-170 kg/m 2 ), and will cost $100$300/m 2 ([USEPA] 2010). A large green roof may end up costing twice the price of a conventional roof but it will pay for itself in the long run by lasting over 50 years compared to the estimated 15 of a conventional roof (Stutz 2010). In a pilot project using a 6.96 cm system the weight was an additional 7.45 kg/m 2 dry and 25.30 kg/m 2 saturated. Therefore, extensive green roofs can effectively be retrofitted to existing rooftops with little additional strain to the roof ([USEPA] 2010). The USEPA and other green roof experts recommend the perennial Sedum as the optimal genus for extensive rooftop vegetation (Oberndorfer 2007; [USEPA] 2010). The Sedum genus contains low growing, drought hardy, flowering plants that can tolerate prolonged stresses of bright sun and high wind. Other plants that would do well are succulents and desert adapted plants. The California Academy of Sciences in San Francisco has managed to install a living roof despite the dips and slopes of the unique roofdesign (California Academy of Sciences 2010). There is a tile-work of biodegradable trays (an example of a Modular system) which plant roots lock together to prevent soil erosion. An open-air terrace allows visitors to experience the roof (California Academy of Sciences 2010). Such public green roofs not only keep the building cooler (10 degrees in this case) but also provide inspiration to urban planners, architects and homeowners (California Academy of Sciences 2010). Germany is an astonishing example of green roof usageabout 13.5 million square meters per year of new green roof is being installed (Oberndorfer 2007).
31 Oberndorfer (2007) cites Haemmerle (2002) as estimating that 14% of all new flat roofs in all of Germany will be green roofs. The groundwork exists for a widespread American green-roof initiative; it just needs to be taken to the next step. Chicago already leads the nation with more green roofs than any other city, it will soon host 2.1 million square meters (Stutz 2010). Looking again at New York, green roofs are beginning to emerge around the city helping mitigate the water crisis. One such example is the 2.5-acre "oasis" on the roof of U.S. Postal Service's landmark Morgan Processing and Distribution facility in midtown Manhattan. The green roof has been active since December 2008, retrofitted to the 1933 building (Stutz 2010). The roof is covered substantially with the genus Sedum and has survived through the extremes of New York seasons without any additional maintenance while providing significant benefits. The green roof has reduced summer runoff by 75% and winter runoff by 40% as well as cooled the building in the summer and insulated in the winter to save an estimated $30,000 per year in energy costs (Stutz 2010). There is a wide range of green roof techniques to fit the needs of the building. Figure 9 shows some types of extensive green roof set-ups.
32 Figure 9. Types of extensive green roofing techniques: (a) Complete system: Every part of the setup is installed as an "integral part of the roof. (b) Modular system: precultivated vegetation trays are installed above existing roof. (c) Pre-cultivated vegetation blankets: growth medium, drainage mats, root barrier, waterproofing membrane and plants are rolled onto existing roof. Taken from (Oberndorfer 2007). Graphics by Jeremy Lundholm There are variations to extensive green roof techniques such as waterproofing below the insulation and other new ideas are likely to become prevalent as the implementation becomes more widespread. After researching varying extensive green roof designs, Brenneisen found that green roofs which are specifically designed to harbor biodiversity show increases in species diversity over years while simpler designs stagnate (Brenneisen 2006). Using local substrate and as many native grasses and wildflowers as possible will help encourage native biodiversity. Endangered or
33 threatened species tend to colonize in undisturbed habitat that closely mimics native habitat (Brenneisen 2006). An intensive green roof, like it sounds, can be a lot of work. It can be covered with as much growth medium as a building can hold. With good architecture, it is possible to support an entire park with trees. Larger buildings fitted with an intensive green roof including small trees, shrubs and a variety of plants and paths for workers or the public to enjoy will increase morale and efficiency (Miller 2005). Greater plant variety provides habitat to a wider variety of insects and animals (Brenneisen 2003). Large flat roofs could be turned into nature preserves that connect to others across the top of an entire city. Green roof architecture could expand to a large field with the help of government incentives or requirements. Figure 10. An intensive green roof with trees and bushes atop the Solaire building in Battery Park City in New York. Taken from (Remer 2011) (Photo Copyright birdw0rks/Simon Bird and the Albanese Organization.)
34 Chapter 3. Inherent Implications Real Roof Results Green roofs sound great in theory but the practical aspect of cost, maintenance, feasibility and weight concerns are yet to be addressed. This section will review projects to give cost estimates, benefits and technical information. The practical reader will inevitably wonder whether the investment in a green roof will pay for itself as well as what type of green roof to install. Case 1: Jean Vollum Natural Capital Center The Jean Vollum Natural Capital Center, Portland, Oregon, has an extensive green roof of 557 m 2 (Paladino, 2004). Total construction cost was $12.4 million dollars ($75,000 dollars more than a conventional roof of that size). Renovation included a roof deck and rooftop fireplace, which increased the actual cost to $1,508/ m 2 Initial costs are approximately twice that of a conventional roof but it has an expected lifespan of 40-50 years, more than twice the span of a conventional roof (10-20 years). The design is known as the German Famos system. It is lightweight and consists of a waterproof membrane, copper root barrier, drainage layer, 5-10 cm of growing medium. Vegetation consists of herbs, succulents and grasses that are native to the region (figure 11) (Paladino, 2004). The drainage layer (unwoven polyester) holds hydrogel crystals that are arranged in rows and absorb and store water when it rains while also creating drainage valleys for excess water.
35 Figure 11. Species used on the Natural Capital Center, Portland, Oregon. Taken from (Paladino, 2004). Case 2: Fairmont Waterfront Hotel A 195 m 2 intensive green roof on top of the Fairmont Waterfront Hotel in Vancouver, British Columbia, also serves as an herb garden (Paladino, 2004) It cost $25,000 USD to re-roof and renovate the building. The Waterfront Hotel green roof was built from a concrete slab topped with 2-ply monolithic membrane supplied by Hydrotech along with 30.5 cm of foam insulation, drainage layer, rocks and growing medium. This construction style makes retrofitting their existing cement roof economical while still providing a structurally sound roof.
36 By utilizing the roof as an herb garden, the restaurant earns $20,000-$25,000 USD in savings, quickly repaying the cost of the roof (Paladino, 2004). The hotel also uses the area as a courtyard and thus requires landscaping investment of $16,000 USD per year. The allure of the rooftop garden attracts customers and provides rooms that open up to the courtyard also increase revenue by allowing the hotel to charge more for rooms with spectacular views, further offsetting the initial cost. Discussion Large crop monocultures, i.e., grass lawns, are highly susceptible to attack from a single pest or virus. Open short grass areas are effectively a dead zones for small mammals, birds and reptiles which may not cross wide-open spaces without cover. As a result, grassy lawns fragment habitats, which decreases the effectiveness of wilderness areas since they are disconnected. Genetic diversity is thought to be essential for the survival of any population (Stiling 2002). When habitats are connected, animals have greater breeding populations. They are healthier and maintain functional ecosystems. A community is a group of interacting organisms that live in the same vicinity (Stiling 2002). A healthy community functions best when all parts are present. Many ecologists hold the belief that communities act as "super organisms" where all the species act together to perpetuate themselves (Stiling 2002). The Florida Everglades is a quintessential example of a community where species are highly interdependent. Alligators are defined as a keystone species, and are vital to supporting a myriad of species in the community. The waterholes they
37 build retain some water through droughts thereby providing habitat and nourishment for a variety of species (Mazzotti, Rice, Percival 2003). In the same way, every species has an effect on the ecology of its environment and other species. Viewing a community as a "super organism," it is apparent that a community missing half its natural members will function at a level well below half of its full potential (Stiling 2002). A human analogy would be living in a small, isolated human community where suddenly all the doctors, blacksmiths and construction workers are removed. Life for those who remain becomes significantly more difficult. In the same way, biological communities depend on each other and suffer when incomplete. As with many movements, improving the ecosystem of an area has to start from the ground up. Soil quality is the first focus of an ecological improvement project. Urban soil usually has high compaction, poor drainage, low organic matter (especially in Florida sandy soils), and low population and diversity of beneficial microorganisms, which are essential to healthy soil (Coder 2001). Landscaping an urban area often means removing fallen leaves, branches and any other "unsightly" organic matter, inhibiting the nutrient cycle. All of the soil nutrients used by plant life are not returned to the ground. This starves recycling organisms that would break down and use organics 1 3 Organic matter and gases released from organic decay normally prevent soil from compacting, allowing roots to absorb nutrients (Coder 2001). A simple way to mitigate this is not to remove organic matter from the cycle. Organics can either be left where they fall or moved to 1 3 Fertilizers become an urban plant's only nutrient source
38 designated areas for decomposition (compost piles). Returning compost to soil improves soil quality. Verdant Verdict The seeds of change have to be sown both in the minds of the public and those who serve them. Politicians and lawmakers should use abundant research showing a positive correlation between increased urban greening and societal benefits to push for public programs to vegetate cities. Performing these improvements creates an expanding job market, improves mental health, efficiency of citizens, and recovery time for humans. Exposure to natural areas has been shown to improve those areas of human health (Kaplan and Kaplan 1989). The ecological benefits of increased habitat, water and air filtration as well as reduced runoff should be incentives to improve biodiversity around cities. Furthermore, the economic benefits of improving the urban environment cannot be ignored: reduction of peak storm-water runoff, the heat island effect, energy usage and construction waste due to more durable, longer lasting, roofs are just some of the benefits that come from a green city. It is vital that in all population centers, especially urban areas, that building efficiency codes be increased and green roofs encouraged. Compliance with new regulations can be encouraged via incentives, but the existence of the regulations often generates a degree of cooperation. Some developers have reported that they do not focus on efficiency because they feel that if it were important, there would be higher standards (Personal communication, Liptan, 2011).
39 Additionally, public support for green' companies should be encouraged so that companies that go beyond set codes are rewarded. Environmentally-conscious city planning must be part of our future because vegetated cities improve human mental and physical well being, wildlife and ecological health. The problems in urban America will not improve unless changes are made. The question is no longer whether humans can afford to implement vegetationit is whether they can afford not to, and they cannot.
40 References Abumrad J and Krulwich R. 2010. Cities. Radiolab. http://www.radiolab.org/2010/oct/08/ Arrhenius O. 1921. Species and area. Journal of Ecology 9(10/17/2010):95--99. Bass B, Liu K, Baskaran. 2003. Evaluating rooftop and vertical gardens as an adaptation strategy for urban areas. BBC. 'Green' exercise quickly 'boosts mental health' [Internet]: BBC News -; c2010a [cited 2010 9/15/2010]. Available from: http://news.bbc.co.uk/2/hi/health/8654350.stm BBC. Water map shows billions at risk of 'water insecurity' [Internet]: BBC News -; c2010 [cited 2011 1/22/2011]. Available from: http://www.bbc.co.uk/news/science-environment-11435522 BBC News Should we learn to love weeds? [Internet]; c2010 [cited 2011 1/22/2011]. Available from: http://www.bbc.co.uk/news/magazine-11523002 Biodiversity a kind of washing powder? [Internet]: BBC News; c2010b [cited 2011 2/1/2011]. Available from: http://www.bbc.co.uk/news/science-environment11546289 Bixler RD, Floyd MF, Hammitt WE. 2002. Environmental socialization: Quantitative tests of the childhood play hypothesis Environ Behav 34(6):795 < last_page> 818. GREEN ROOFS HOW NATURE RETURNS TO THE CITY [Internet]: International Conference on Urban Horticulture; c2003 [cited 2011 2/15/2011]. Available from: http://www.actahort.org/books/643/643_37.htm Brenneisen S. 2006. Space for urban wildlife: Designing green roofs as habitats in switzerland Brooklyn Feed. Green Roof [Internet]; c2011 [cited 2011 3/28/2011]. Available from: http://www.brooklynfeed.com/2010/05/green-roof/ CAS. The Living Roof: California Academy of Sciences [Internet]; c2010 [cited 2010 11/3/2010]. Available from: http://www.calacademy.org/academy/building/the_living_roof/ Coder KD. 2001. Chapter 7: Site assessment and soil improvement School of Forestry Resources and Conservation, Florida Cooperative Extension Service,
41 Institute of Food and Agricultural Sciences, University of Florida. Costanza R et al. 1997. The value of the world's ecosystem services and natural capital. Center for Environmental and Estuarine Studies. Duryea ML. 2001. Chapter 1: Restoring the urban forest ecosystem: An introduction. University of Florida ExtencionInstitute of Food and Agricultural Sciences Ellis, J. Colony Collapse Disorder UF/IFAS Extension: Solutions for Your Life [Internet] [cited 2011 1/20/2011]. Available from: http://solutionsforyourlife.ufl.edu/hot_topics/agriculture/colony_collapse_disorde r.html Evans PB. 2002. Livable cities?: Urban struggles for livelihood and sustainability Berkeley: University of California Press. Feister U and Grewe R. 1995. SPECTRAL ALBEDO MEASUREMENTS IN THE UV and VISIBLE REGION OVER DIFFERENT TYPES OF SURFACES. Photochem Photobiol 62(4) :736-44. Getter KL and Rowe DB. 2006. The role of extensive green roofs in sustainable development. HORTSCIENCE 41(5):1276--1285. Hornback JM. 2006. Organic chemistry Belmont, CA: Thomson Brooks/Cole. James, F. Obama Returns Solar Panels To Place In Sun On White House : It's All Politics : NPR [Internet]; c2010 [cited 2011 3/13/2011]. Available from: http://www.npr.org/blogs/itsallpolitics/2010/10/05/130354356/obama-returnssolar-panels-to-place-in-sun---on-white-house Jim CY and Liu HT. 2001. Patterns and dynamics of urban forests in relation to land use and development history in guangzhou city, china. Geogr J 167(4):358-75. Kaplan R and Kaplan S. 1989. The experience of nature: A psychological perspective. Cambridge ; Cambridge University Press, 1989. Kellert SR and Wilson ER. 1993. The biophilia hypothesis. Island Press. King, J. Landscape+Urbanism: A Panopoly of Green Roofs [Internet]; c2008 [cited 2011 3/28/2011]. Available from: http://landscapeandurbanism.blogspot.com/2008/06/panopoly-of-greenroofs.html Khler M. 2002. Green roofs in temperate climates and in the hot-humid tropicsfar beyond the aesthetics. Environ Manage Health 13(4):382.
42 Korhnak LV. 2001. Chapter 6: Restoring the hydrological cycle in the urban forest ecosystem. School of Forest Resources and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Lowman MD and Rinker HB, editors. 2004. Forest canopies. Second ed. Mazzotti, F. SOFIA SFRSF Wildlife & Wetland Ecology How's Restoration Improved by Research? Monarchs [Internet]: USGS; c2003 [cited 2011 3/13/2011]. Available from: http://sofia.usgs.gov/sfrsf/rooms/wild_wet_eco/gator_croc/ McPherson E and Rowntree R. 1993. Energy conservation potential of urban tree planting. Journal of Arboriculture McPherson E, Nowak D, Rowntree R. 1994. Chicago's urban forest ecosystem: Results of the chicago urban forest climate project. General Technical Report NE-186 ed. Radnor, PA: USDA Forest Service, Northeast Forest Experiment Station. Mentens J. 2006. Green roofs as a tool for solving the rainwater runoff problem in the urbanized 21st century? Landscape Urban Plann 77(3):217. Miller JR. 2005. Biodiversity conservation and the extinction of experience. Trends in Ecology & Evolution 20(8):430-4. NOAA's Coral Reef Data [Internet]: US Dpeartment of Commerce/ NOAA; c2011 [cited 2011 3/9/2011]. Available from: http://www8.nos.noaa.gov/coris_glossary/index.aspx?letter=r Oberndorfer E. 2007. Green roofs as urban ecosystems: Ecological structures, functions, and services. Bioscience 57(10):823. Paladino & Co. Inc. 2004. Kings County Office. [cited 2011 5/9/2011]. Available from: your.kingcounty.gov/.../greenbuilding/.../KCGreenRoofStudy_Final.pdf Pauly D. 1995. Anecdotes and the shifting baseline syndrome of fisheries Payton I and Fenner M. Keystone species: The concept and its relevance for conservation management in new zealand 2002. Preston FW. 1960. Time and space and the variation of species Ecology 41(4):611. Remer, L. Beating the Heat in the World's Big Cities : Feature Articles [Internet]; c2011 [cited 2011 3/28/2011]. Available from: http://earthobservatory.nasa.gov/Features/GreenRoof/greenroof3.php
43 Roberts, M. Common weed petty spurge 'could treat' skin cancer [Internet]: BBC News [cited 2011 1/27/2011]. Available from: http://www.bbc.co.uk/news/health-12275507 Rosenzweig M. Ziv, Y. Ecography, Vol. 22, No. 6 (Dec., 1999), pp. 614-628 [Internet]: Blackwell Publishing; c1999 [cited 2010 10/17/2010]. Available from: http://www.jstor.org/pss/3683315 Rosenzweig ML. 2003. Reconciliation ecology and the future of species diversity. Oryx 37(02):194. Ruiz-Jan MC and Aide TM. 2006. An integrated approach for measuring urban forest restoration success. Urban Forestry & Urban Greening 4(2):55-68. Schneider J. 2009. Vegetated-roof failure teaches valuable lessons -. Eco-Structure Magazine: Shukman, D. One-fifth of world's plants at risk of extinction [Internet]: BBC News; c2010 [cited 2010 10/18/2010]. Available from: http://www.bbc.co.uk/news/science-environment-11434109 Smith, B. Prison health care costs topped $230 million | health, million, bodycopyrag Local Sun Journal [Internet]. North Carolina: Sun Journal; c2010 [cited 2011 4/4/2011]. Available from: http://www.newbernsj.com/articles/health-70242million-bodycopyrag.html Stiling P, editor. 2002. Ecology theories and applications. Fourth ed. Prentice Hall. 402 p. Stutz B. 2010. Green roofs are starting to sprout in american cities. Yale Environment. Tischendorf L. 2000. On the usage and measurement of landscape connectivity. Oikos 90(1):7. Todd DK. 1960. Salt water intrusion of coastal aquifers in the united states. Subterranean Water :452,452461. ULRICH R, SIMONS R, LOSITO B, FIORITO E, MILES M, ZELSON M. 1991. Stress recovery during exposure to natural and urban environments J Environ Psychol 11(3):201
44 Vegetated Roof Cover [Internet]. Philadelphia, PA: US EPA [cited 2010 10/17/2010]. Available from: http://www.epa.gov/owow/nps/roofcover.pdf Vorosmarty CJ, McIntyre PB, Gessner MO, Dudgeon D, Prusevich A, Green P, Glidden S, Bunn SE, Sullivan CA, Liermann CR, et al. 2010. Global threats to human water security and river biodiversity. Nature 467(7315):555-61. Walsh CJ, Fletcher TD, Ladson AR. 2005. Stream restoration in urban catchments through redesigning stormwater systems: Looking to the catchment to save the stream. J N Am Benthol Soc 24(3):pp. 690-705. Warren LS. 2003. American environmental history. Malden, MA: Blackwell Pub. Worden E, Guidry D, Alonso Ng A, Schore A. 2004. Green roofs in urban Landscapes 1 Environmental Horticulture Department 2010. Yang J, Yu Q, Gong P. 2008. Quantifying air pollution removal by green roofs in chicago. Atmos Environ 42(31):7266-73.