Arboriculture & Urban Forestry 35(2): March 2009 Arboriculture & Urban Forestry 2009. 35(2): 87–93 87 Residents’ Perception of Tree Diseases in the Urban Environment Cristina Nali and Giacomo Lorenzini Abstract. Urban greenspaces are essential for the health and well-being of citizens and the presence of trees is a key element for the improvement of urban environments. But trees may become a factor of risk for the citizen when they are diseased, declin- ing or dead. Common people are usually unaware of the intimate causes of plant diseases. Based on a balanced sample of 944 detailed interviews carried out in a structured format by university students, a survey was performed to monitor the perception of citizens of evergreen ornamental plants (Quercus ilex) killed by a root disease. Most of the interviewed were customary or moderate frequenters of the venue. Most of the respondents were able to recognize the differences between the dead tree and other conspecific normal individuals, and 86.2% were aware of the risks connected with the collapse of unhealthy trees. Differ- ences amongst genders, age groups, educational levels, and occupation were observed concerning the supposed cause of the death (due to a fungal rot disease). Environmental pollution was indicated as the culprit mainly by young people. Surprisingly, 42.9% of respondents were unable (or unavailable) to give suggestions to administrators concerning the management of public greenery. Key Words. Environmental Psychology; Declining Trees; Group Interviews; Greenspaces. The globe continues to urbanize such that more than half of human beings live in areas with “urban” characters; with two-thirds of all Europeans now residing in towns or cities (European Environment Agency, 1998). Urbanization is the dominant social phenomenon in all developing countries. It is generally believed that looking at natural scenery increases one’s feeling of well-being, and contact with nature elicits psychological as well as physiological benefits (Parson 1991). Urban green areas are indicators of the perception of increased, residential environmental quality (Bonaiuto et al. 1999) and actually provide many environmental and social ben- efits (Smardon 1988). For instance, they positively alter micro- climate through the production of shade, wind reduction, erosion control, pollutant removal, and noise abatement (Givoni 1991; Avissar 1996). Urban greenery has invaluable emotional, psycho- logical, healing, and even spiritual values for many people. Even if most of the values attached to green areas are nonpriced envi- ronmental benefits, the presence of greenery significantly contrib- utes to increase the market values and attractiveness of buildings and properties (Luttik 2000). Furthermore, high quality green and treed spaces increase the attractiveness of a city and promote it as a tourist destination, generating employment and revenue. Trees are the largest and longest lived forms of life on ter- restrial earth and are highly important to the characterization of urban landscapes. They are regarded as the most enjoyable as- pect of urban gardens (Bennett and Swasey 1996), and are es- sential elements in most landscape design. In a given species, the ultimate features of a tree canopy are shaped by leaves and branches, and reflect health, growing conditions, and age of the individual tree. Plants, as well as all living beings, are victims of diseases and some of these can be lethal (Agrios 2005); the disease and the specific site conditions in urban areas (character- ized by soil compaction, water stress, limited root space, wound- ing, and pollution) may reduce growth and vitality [most trees have smaller diameters than rural conspecifics of the same age (Quigley 2004)] or increase mortality of amenity trees (Marion et al. 2007). Urban trees may appear to be suffering, unhealthy or even dead to a citizen who is unaware of the intimate causes of the phenomena. Because plant pathology is the discipline which studies biotic (i.e., infectious) and abiotic factors responsible for stressing plants and reducing their quantitative and qualitative performances, one can promote knowledge of the relationship be- tween natural environment and human psychological processes. This study was carried out in the warm season of 2004 in Tuscany (central Italy) in order to assess the level of percep- tion of diseases of trees by citizens, a subject that has never been covered before by environmental psychology literature. METHODS Location and Subjects The survey was performed in the cities of Pisa and Livorno and in some minor urban centers of their districts. Firstly, a pilot investi- gation was conducted to select examples of typical study cases of diseased urban trees. The paradigmatic case was represented by single, isolated, mature (but not senescent) individuals of holm oak (Quercus ilex L.), an evergreen tree with fine foliar texture, indigenous of the Mediterranean basin, where it is widespread in urban forestry. These trees were in public gardens/boulevards and had foliage completely necrotic (brown) but still leaning (i.e., they were not defoliated); they were standing amongst similar individ- uals in good conditions. Holm oak is a long-living species, and its lifespan may develop over several centuries; rough estimates of the age of the individuals selected in this study are 50–80 years. People were randomly approached around these dead/declin- ing trees, while standing/walking in the surroundings and were briefly informed about survey’s objective and answering proce- dure. In all, 944 participants were positively involved. Sample breakdown according to gender, age, education, and occupational ©2009 International Society of Arboriculture
March 2009
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