22 Östberg and Sjögren: The LITA Model for Economic Valuation of Urban Trees ing on other factors; e.g., tree placement, vitality, damage, or aesthetics (Moore 1992; CTLA 2000; Cullen 2002; Randrup 2005; Helliwell 2008). Some models allow an increase in the base cost if the tree has aesthetic characteristics (Randrup 2005), while others only decrease the base cost (CTLA 2000). The possibility of increasing the value based on amenity is also something that has been discussed (Cullen 2002), the conclusion being that amenity values should only decrease the economic value. The method used to calculate the base value also differs between models. Some use fixed base values that are regulated by a central committee (Helliwell 2008), others are based on plant nursery prices (Moore 1992; Randrup 2005; CAVAT 2010). The base values are then scaled up depending on tree size, a method that also varies between models. For example, some base values are based on stem circumference (Ran- drup 2005), others on cross-sectional area (CTLA 2000; CAVAT 2010) or tree volume (Moore 1992). As for the base cost calculation and the adjust- ment factors, consideration of tree age also dif- fers between models. In some models, the value decreases if the tree has reached a certain age (Randrup 2005; Bulíř 2009), but there is dis- agreement regarding when the reduction due to tree age should take effect, how steep the reduc- tion slope should be, and how maximum tree age should be valued (Randrup 2005; Bulíř 2009). In the seven existing models reviewed here— i.e., CAVAT (2010), CTLA (2000), Helliwell (2000), the Koch method (Bulíř 2009), the revised Burnley method (Moore 1992), STEM (Flook 1996), and VAT03 (Randrup 2005)—some form of reduction is made due to damage and/or reduction of vitality. This is the only parameter that forms part of all these models and it only reduces the economic value of the tree. There are differences in how damage and/ or vitality are defined, but usually several separate parameters together give a total score concerning damage and/or vitality (Flook 1996; Randrup 2005). The variations in calculating the base cost, scal- ing, and adjusting the factors lead to wide variation in the final value (Watson 2002). The profusion of models has also resulted in a situation where several different models are used within the same country, consequently confusing the courts (Randrup 2005). A trend has also been noted for courts in Sweden to question aesthetic value [e.g., Lämna v Tellstig ©2016 International Society of Arboriculture (2008) and Lämna v Tellstig (2010), where the Dis- trict Court and Court of Appeals made different conclusions on the aesthetic values of the same trees], which in some models can account for the majority of the total value (Randrup 2005). There is thus a need for a simple model that is easy to explain and update, and that does not rely on ‘soſt’ values, such as aesthetics, architectonics, and growing site. The aim of this study was therefore to develop a model that is easy to assess and understand, and that can work well within the Swedish legal system. The purpose of the model is to calculate the replace- ment cost of a tree of the same species, location, and condition as the tree being valued, using the cross-sectional area to extrapolate, from a band of known prices, to a base price for any desired size that can then be adjusted using appropriate factors. MATERIALS AND METHODS In constructing a tree appraisal model, in the pres- ent case for Sweden, it was deemed important to have clear goals for the model. Three points were considered to be of key importance: 1) The model should reflect the change in the market price with respect to tree size for a specific tree spe- cies; 2) the calculated tree price should be based on the lower base value option, in order to limit the impact of accusations that the extrapolation resulting in the tree replacement cost is an over- estimation; and 3) each step in the model should be simple to explain to the courts and to users. The research was divided into three main tasks: i) finding a way to calculate a base cost based on tree nursery prices that would reflect the market price of urban amenity trees, ii) find- ing and describing appropriate adjustment fac- tors, and iii) finding a model for calculating the planting costs for common planting conditions. Plant Nursery Prices for Trees The base cost calculation was based on tree nursery prices in accordance with VAT03 (Randrup 2005), CAVAT (2010), and the revised Burnley method (Moore 1992). Data were obtained from six tree nurseries (three German and three Swedish). These plant nurseries were selected through a questionnaire that was sent out to 14 cities, housing companies, and cemeteries in Sweden that had previously shown an interest in the question of economic
January 2016
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