80 Ponce-Donoso et al.: Appraisal Using Twelve Valuation Formulas and Two Appraiser Groups findings that are similar to what were reported in other studies (Watson 2002; Ponce-Donoso et al. 2012; Ponce-Donoso et al. 2013). Researchers also note that STEM formulas exhibited high val- ues, although with only a moderate dispersion. In comparing the experience level of appraisers (i.e., SG and JG), significant statistical differences were found, though the difference was minimal if the average ranking is considered (Table 3; Figure 1). This indicates further training could reduce the probability of statistical differences. When comparing all appraisers, in one group, statisti- cally significant differences were found, thereby resulting in three different groups. Neverthe- less, rankings were not ordered in function of the group’s experience (Table 3; Figure 1), thus the individuals’ experience would not be a differ- entiating factor, statistically speaking. As shown in Table 3, Group L incorporated three apprais- ers with experience and one without, Group M included two experienced and two inexperienced appraisers, and Group N had two experienced and four inexperienced appraisers (Table 3). Thus, the lower average value was obtained by two senior appraisers (S1 and S2), and the highest valuation was also obtained by one of these, while all JG appraisers are located within the ranking (Table 3). On the other hand, the role of experts in appraisal procedures, provided a distinctive ele- ment in the valuations, where the most experi- enced appraisers consistently tended to get lower values in their valuation (Cullen 2005), which was contrary to the norm that experience is a require- ment for the appraisal of the tree (Price 2003; Tyrväinen et al. 2003). This shows the need for a minimum level of instruction to obtain the pro- fessional skills necessary for implementing a for- mula, considering that these appraisers had more of an ad hoc professional training. Therefore, when considering this particular case, the Danish Method, French Method, CTLA Method, Swiss Method, Peñalolén Method, Italian Method, and COPIMA (excluding Norma Granada, Helliwell, Burnley, Tedesco, and STEM) have no statisti- cally significant differences between the type of appraisers or among the eight appraisers. CONCLUSIONS Overall, researchers found statistically sig- nificant differences between the medians of the studied formulas, among types of appraisers, and among individual appraisers. This indicates that the valuation of urban trees depends preferably on the specific formula used (i.e., type and its con- stituent variables) as well as the appraiser’s experi- ence; aspects that coincide with studies by Watson’s (2002), Contato-Carol et al. (2008), Grande-Ortiz et al. (2012) and Ponce-Donoso et al. (2012; 2013). The formulas that presented the best comparative performance as defined by dispersion and loca- tion of the median, were the Helliwell, Norma Granada, Tedesco, Burnley, and CTLA Methods, while the lower performance were found in the French, Swiss, Danish, and STEM Methods. Researcher note findings that when show that the ers were organized into three homogeneous groups, experience apprais- did not seem to be a factor that differed statisti- cally. Group N was the largest group, com- posed of 75% of the appraisers, all JG, and only two SG (Table 3). Group L included four appraisers and only one having junior experi- ence, while Group M was composed of two each (Table 3). Again, the experience would be a determining factor when it comes to valua- tion of urban trees (Grande-Ortiz et al. 2012). The results show that the use of parametric formulas is recommended when appraising urban trees in international contexts. This was observed by the ability of formulas to dis- criminate the value of trees, resulting in the graphic dispersion of monetary values pre- sented in the rankings (i.e., high dollar amount for higher value tree, medium monetary value for mean tree, and lowest for those with a lower value monetary values). In this study, these features were identified in the CTLA, Helliwell, and Norma Granada Methods. Acknowledgments. The authors thanks to Fondo Nacional de Desarrollo Científico y Tecnológico of Chile (FONDECYT) Project 1130264 for funding this project. ©2017 International Society of Arboriculture
March 2017
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
