|
Urban forestry is the careful care and management of tree populations in urban settings for the purpose of improving the urban environment. Urban forestry advocates the role of trees as a critical part of the urban infrastructure. Urban foresters plant and maintain trees, support appropriate tree and forest preservation, conduct research and promote the many benefits trees provide. Urban forestry is practiced by municipal and commercial arborists, municipal and utility foresters, environmental policymakers, city planners, consultants, educators, researchers and community activists. ==Functions and values== Function, the dynamic operation of the forest, includes biochemical cycles, gas exchange, primary productivity, competition, succession, and regeneration. In urban environments, forest functions are frequently related to the human environment. Trees are usually selected, planted, trimmed, and nurtured by people, often with specific intentions, as when a tree is planted in a front yard to shade the driveway and frame the residence. The functional benefits provided by this tree depend on structural attributes, such as species and location, as well as management activities that influence its growth, crown dimensions, and health. Urban forest functions are thus often oriented toward human outcomes, such as shade, beauty, and privacy. As prominent "things," arranged in distinctive formations, trees command a symbolic and material presence that informs how places and landscapes are imagined. This link that humans have to trees has been theorized by Kellert and Wilson (1993) to be a genetically based emotional need to be close to trees and other greenery. According to their "Biophilia Hypothesis," millions of years of human survival and evolution depended on our ability to cope with the natural world; learning what was safe and dangerous involved the imprinting of strong positive and negative emotional reactions to various natural stimuli. Although 21st century American society is no longer as dependent on nature for day-to-day survival, Kellert and Wilson suggest that closeness to the natural world is still critical for psychological well-being. The complex symbolic and emotional ties that humans have with trees have important implications for the importance of sound urban forest management practices that impact not only quality of life on an ecological level, but on the human and cultural level. People develop emotional attachments to trees that give them special status and value. Removing hazardous trees can be difficult when it means severing the connection between residents and the trees they love. For many, feelings of attachment to trees in cities influences feelings for preservation of trees in forests (McPherson 1998). The value that people place on trees is especially evident with respect to big trees. There has always been a public fascination with large trees, especially the largest specimens of trees that reach a mature height of greater than 40 or 50 feet (i.e., Champion Trees) (Barro et al. 1997, Dwyer et al. 1991). Moreover, the ability of big street trees to create a ceiling of branches and leaves over all or part of a street impacts the scale of changing shadows cast by the trees, sunlight filtration, and other human-scale considerations that provide a changing visual environment (Zube 1973, Jones and Cloke 2002). In their qualitative study of Denmark residents’ perceptions of the importance of the urban forest, Hansen-Moller and Oustrup (2004) found that the scale of urban trees was one of the main conditions of an "ideal" urban forest, through its volume, height, and ability to envelop a person, thus creating a barrier from the outside world. Urban forests bring many environmental and economic benefits to cities. Among these are energy benefits in the form of reduced air conditioning, reduced heating by shading buildings, homes and roads, absorbing sunlight, reducing ultraviolet light, cooling the air, and reducing wind speed - in short improvement of the microclimate and air quality (McPherson 1994; McPherson & Rowntree 1993; Simpson & McPherson 1996; Coder 1996; Wolfe 1999; Hastie 2003; Lohr ''et al.'' 2004). There are also economic benefits associated with urban trees such as increased land, property, and rental value (Morales et al. 1983; Anderson & Cordell 1988; Wolf 1998; Dwyer et al. 1992; Mansfield et al. 2005; Orland et al. 1992; Hastie 2003; USDA Forest Service 2003, 2004). Well-maintained trees and landscaped business districts have been shown to encourage consumer purchases and attract increased residential, commercial and public investments (Wolf 2004, 2007). Trees located in business areas may also increase worker productivity, recruitment, retention and satisfaction (Kaplan & Kaplan 1989; Kaplan 1992; Wolf 1998). Urban forests also improve air quality, absorb rainwater, improve biodiversity and potentially allow recycling to 20% of waste which is wood-based〔McPherson E.G. (2006). (Urban Forestry in North America ). in ''Renewable Resources Journal'', Autumn 2006, pp8-12〕 Many cities today are dealing with stormwater management system issues where their existing systems can no longer hold the volume of water that falls in storms. One sustainable solution to this is planting street trees with grates underneath them to hold water. Trees and their soils work to filter runoff pollution and soil contaminants by absorbing them and processing them into less harmful substances.〔 They also collect water in their limbs and release it back into the atmosphere over time.〔 This makes trees a solution to stormwater runoff issues and urban heating issues. The social and even medical benefits of nature are also dramatic. Urban poverty is common to areas lacking green spaces.〔 Visiting green areas in cities can counteract the stress of city life, renew vital energy and restore attention, and improve medical outcomes.〔Cimprich B. (2007). (Attention Restoration Theory: Empirical Work and Practical Applications )〕 Simply being able to see a natural view out of the window improves self-discipline in inner city girls.〔Taylor A.F, Kuo F.E, Sullivan W.C (2001). (Views of Nature and Self Discipline: Evidence from Inner City Children ) in ''Journal of Environmental Psychology'' (2001), vol. 21.〕 Having regular access to woodland is desirable for schools,〔Robertson J., Martin P., Borradaile L. and Alker S. (2009) (Forest Kindergarten Feasibility Study ), published by the Forestry Commission〕 and indeed Forest kindergartens take children to visit substantial forests every day, whatever the weather. When such children go to primary school, teachers observe a significant improvement in reading, writing, mathematics, social skills and many other areas.〔Gorges R. (Waldkindergartenkinder Im Ersten Schuljahr )〕 Various methods are available to capture the value of urban trees, each designed to analyse a specific type of green space (individual trees, parks, trees on golf courses etc.). The following are examples of studies that have used these different approaches, along with their respective constraints. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Urban forestry」の詳細全文を読む スポンサード リンク
|