132 for obtaining the monetary value of an individual tree. Various papers discussing this issue show the divergence of views (De Groot et al. 2002; Contato 2004; Babier and Heal 2006; Mc- Comb et al. 2006; Heal 2007; Donovan and Bruty 2008). The contingent valuation method involves directly ask- ing people, in a survey, how much they would be willing to pay for specific environmental services and is the most widely used method for estimating non-use values (Schulze et al. 1983; Morey et al. 1991; Xu et al. 2003; Jim and Chen 2006a; Vesely 2007; Zhu et al. 2007; Bernath and Roschewitz 2008; Chen and Jim 2008; Lo and Jim 2010; Becker and Freeman 2010). Most urban trees are on public lands, thus making this method difficult to use for assessing urban trees, as local governments do not often have staff for surveying. The hedonic pricing method estimates the value of en- vironmental amenities that affect the prices of marketed goods. The method is based on the assumption that people value the characteristics of a good rather than the good it- self. Prices will therefore reflect the value of a set of char- acteristics (including environmental characteristics) that people consider important when purchasing the good (Mo- rales 1980; More et al. 1988; Tyrväinen 1997; Tyrväinen and Miettinen 2000; Laverne and Winson-Geideman 2003; Price 2003; Morancho 2003; Jim and Chen 2006b; Wolfe 2007; Sander et al. 2010). This method requires the inter- mediary of house prices to estimate tree value. If the trees are widely scattered in the city, a large amount of data may be required, possibly making this approach impractical. Integrated methods employing remote sensing, computer modeling, and computation techniques make it possible to assess the aggregate benefits of the tree cover of a city, but are not suitable for individual tree assessment (Jim 2006). These methods are not used in the official valuation of ur- ban trees in administrative regulations. In these cases, the val- uations are based on tree appraisal methods, as they allow the monetary value of an urban tree to be determined. The objec- tive of the present review is to study these appraisal methods. APPRAISAL METHODS The different methodologies have been classified into three groups (Espluga 1989): multiplicative or parametric meth- ods, economic or capitalization methods, and mixed methods. Using multiplicative or parametric methods, the value is deter- mined by the equation: [1] peal, location, historical significance, etc. In these methods, t (age of the tree) is another variable of the valuation equation. Economic or capitalization methods are based on the appli- cation of different procedures for evaluating investments. They distinguish between objective and subjective criteria, which are combined in the previous group. They make it possible to set a monetary value for a living element via the following equation: where x1, x2 Value = ƒ(x1 ,....,xn [2] Value = ƒ(t) where t is the age of the tree. ©2012 International Society of Arboriculture ,x2 ,x3 ,x4 , .......,xn ) , are the variables of type, aesthetic ap- [6] The Value = E × B × L × D × T Italian method Value = P × I × S × C (Fabbri 1989) uses the fol- lowing formula to calculate the value of a tree: [7] This method takes into account the base price of the same spe- cies in a nursery (P); an index (I) reflecting the tree’s state of health and appearance on a scale of 1 to 10; a location index (S) with values of between 6 and 10, according to whether the Grande-Ortiz et al.: Methods of Tree Appraisals Mixed methods are based on a system that combines capitalization and parametric indices. The value formula is: [3] ables Value = ƒ(t; x1 type, , ... ,xn aesthetic ) where t is the age of the tree and x1, ..., xn of appeal, location, etc. , are the vari- If the ini- tial value is obtained by means of a capitalization meth- od, t is included in the equation. If the initial value is obtained by a parametric method, t must be parameterized. Multiplicative or Parametric Methods The Value = Vb × BA × S × E × I × T × R Tedesco method (Bernatzky 1978) uses the fol- lowing formula to calculate the value of a tree: [4] where Vb is a value of market price for tree per cm2 of basal area, BA is the section of the basal area, S is a variable defin- ing the location (open country 1.3, country 1.5, forest 1.8, city 2, downtown 3), and E represents the condition of the tree on a descending scale from 1 for completely healthy, to 0 for a very ill and weakened specimen. I, an index, reflects the tree’s envi- ronmental compatibility on a descending scale, from 1 for com- pletely compatible to 0.1 for not compatible, T is an index that reflects the ratio between life expectancy and age of tree, and R is the percentage reduction in value due to damage to the tree. The Swiss method (Ferraris 1984) takes into consideration four basic indices: species (E), state of health and aesthetic value (B), location (U), and size (D). These variables are separated qual- itatively to avoid errors of judgment. This method also evaluates damage to trees, including damage that does not involve the total loss of the tree. The method makes use of the following formula: [5] Value = E × B × U × D The French method (Ferraris 1984) establishes an index re- lated to the cultivation care (T) required for the maintenance of the specimen. Ferraris (1984) reviewed the Swiss methodol- ogy and adapted it to include T in the valuation expression in order to fix a monetary value for trees in private parks and gar- dens in France. This method attempts to define the most likely cost of replacement. The value is obtained via the use of four indices: a species index (E), an index of health and aesthetic value (B), a location index (L), and a size index (D) (with val- ues determined according to the ranges of the normal circum- ference). The following expression is used for tree valuation:
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