Methods of Tree Appraisal: A Review of Their Features and Application Possibilities

Abstract

Urban trees perform a number of basic functions related to the environment and the welfare of city dwellers (ecological, recreational, psychological), although their benefits are not readily quantifiable. However, in certain situations, it is essential to assign an economic value to the trees. There are currently various methods for valuing the benefits of trees and greenspaces in human settlements, including statistical methods, the travel cost method, contingent valuation, the hedonic pricing method, and integrated methods. However, these methods are not used in official valuations of urban trees; in these cases, appraisal methods are used. The aim of this paper is to study the appraisal methods used for their detailed features and the possibilities of their application. The main conclusion of this review is that there are a number of methods with different types of application. The best method is selected according to tree location, type of land ownership, and the availability of data. Methods with a higher degree of applicability are CTLA, a parametric method of low difficulty, and Contato, a mixed method of medium difficulty. In any case, it is advisable to increase efforts to objectify the correction index in the case of parametric and mixed methods.

Selection of Tree-Size Variables for Appraisal Methods for Urban Trees According to Their Collinearity

“…The formulaic expert method (FEM) alone uses a combination of some of these tree-size variables for the trunk and crown, rather than age, as reliable data were unavailable for heritage trees in Hong Kong, as is the case in most cities (Jim 2006). In contrast, capitalization methods use age as the only variable (Grande-Ortiz et al 2012). This work therefore aims to establish which variables can explain the most variability with no problems of collinearity, in order to reduce costs in urban tree inventories.…”

“…Age can be considered a basis for comparison independently of species (Hegedüs et al 2011). The basal area (g) can be calculated with the average circumference (c), which is the variable employed in the American method of valuation (CTLA 1992;CTLA 2000), and is one of the most commonly used (Grande-Ortiz et al 2012). Height (h) is one of the most widely-applied tree-size variables in urban tree inventories (Wood 1999;Martin et al 2011;Moskal and Zheng 2012;Shrestha and Wynne 2012), and is also used indirectly in FEM and through corrective measures of basic value (Grande-Ortiz et al 2012).…”

“…The basal area (g) can be calculated with the average circumference (c), which is the variable employed in the American method of valuation (CTLA 1992;CTLA 2000), and is one of the most commonly used (Grande-Ortiz et al 2012). Height (h) is one of the most widely-applied tree-size variables in urban tree inventories (Wood 1999;Martin et al 2011;Moskal and Zheng 2012;Shrestha and Wynne 2012), and is also used indirectly in FEM and through corrective measures of basic value (Grande-Ortiz et al 2012). Canopy area (ca) is another variable for calculating tree size that is easy to measure with current methods of photogrammetry (McRoberts and Tomppo 2007;Walton 2008;Abd-Elrahman et al 2010;Millward and Sabir 2011); it is also a feature of the CON-TATO and FEM valuation approaches (Grande-Ortiz et al 2012) and can be used to determine the Location Index (Ayuga-Téllez et al 2011).…”

“…The variables most frequently used are basal area, normal circumference, height, dbh (diameter at breast high), normal area of the trunk, volume, canopy area, and age (Grande-Ortiz et al 2012). Age is the most important variable used in non-parametric assessment methods; that is, capitalization and mixed methods (Ponce-Donoso et al 2009;Grande-Ortiz et al 2012). No measuring is required if the municipality records woodland planting data.…”

Comparación entre métodos de tasación y valoración del público para el arbolado urbano de Madrid

“…El uso de diferentes métodos en la valoración monetaria de activos naturales y recursos medioambientales, es una aproximación que contribuye en gran medida a la planificación del uso del suelo y al establecimiento de prioridades para preservar el paisaje natural (Mieko et al 2012). Existen numerosas fórmulas o métodos de valoración específica para el arbolado urbano y cada una tiene una aplicabilidad diferente (Grande-Ortiz et al 2012). Un mismo árbol tiene un valor económico distinto dependiendo del método utilizado.…”