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ŠUMARSKI LIST 11-12/2019 str. 61     <-- 61 -->        PDF

method (Table 4). The most frequently suggested management measure by ISM method was sanitation cutting (68.3%), whereas for the UFMO method, the most frequent was salvage cutting (42.1%). Pruning was the second most frequently suggested measure (25.6%) for the UFMO method, whereas for the ISM method it wasn’t suggested at all. Tending was suggested by both the ISM and UFMO methods (17.8% and 10.8%, respectively). Altogether, the UFMO method performed better at providing management measures expressed in relative area and relative time, as shown in Table 1.
DISCUSSION AND CONCLUSIONS
RASPRAVA I ZAKLJUČCI
This study focused on the comparing of two methods for surveying urban forest health, with each having different designs and purposes. Consequently, the main difficulty was to find appropriate performance measures common to both methods. The UFMO method exceeded ISM for the all chosen performance measures regarding time, except the amount of data gathered. We concluded that the UFMO method was economically more appropriate for surveying urban forest health because the same area was inventoried in 5.4 times less time than required by ISM. Therefore, we can recommend the UFMO method over ISM for surveying urban forest health. When the purpose of surveying urban forest health is the detailed analysis of smaller areas, the ISM method is appropriate because it takes into a consideration more trees and more damaging agents per unit area in comparison to the UFMO method. In cases when the purpose of the surveying is oriented toward the short-term management of an urban forest, we would again recommend the UFMO method, which is capable of providing more management measures and finding more standing dead trees per hour and per unit area.
Discrepancies between the two methods were expected because of their different purposes and designs. The survey in the UFMO method focused on areas with a higher number of urban forest visitors, i.e. forest paths and parks, and this is very likely the reason that some damage factors were more frequent, e.g. mechanical damage and leaning (Table 2). The ISM method focuses on crown condition, resulting in a higher frequency of damaging agents on leaves and needles, e.g. Dryocosmus kuriphilus, Erysiphe alphitoides and Lophodermium spp. Furthermore, the ISM method recorded more attribute data than the UFMO method, e.g. symptoms, the affected part of the tree, and the percent of defoliation, which resulted in a slower inventory. Because more time was spent on the single plot, more details were noted for smaller areas, and the ISM method recorded more trees and more damaging agents per unit area.
ISM uses a representative sample that can be used to make inferences with respect to the entire population, i.e. all trees within an urban setting. It was designed to provide several estimates of different population parameters, not just the number or proportion of trees with various health issues. Measurements of trees, dead wood, and small trees were made on the ISM plots. Equivalent measurements were not included as part of the UFMO method. The UFMO method was designed to specifically assess urban tree health; therefore, it is no surprise that it can do this task more efficiently than the ISM method. However, it does not use a representative sample and should not be used to make inferences regarding the entire population. If the UFMO method was applied repeatedly through time in the same areas, it would give an idea of the change in the health status of urban trees through time and perhaps could be used to assess the effectiveness of management activities aimed at improving urban forest health. However, even with this application, the UFMO method would require the assumption that the changes in tree health in the areas being monitored (i.e. the areas immediately along trails) are representative of changes elsewhere within the urban forest if the results are to be generalized over the entire urban area. For the same sampling cost, the ISM approach would produce an unbiased but imprecise estimate of overall forest health, while the UFMO method would produce a biased but more precise estimate. In conclusion, the UFMO method is more appropriate for performing tree health surveys than for monitoring urban forest health.
Primarily, we surveyed paths with a relatively high number of visitors and forest areas that are close to, or even adjacent to, real estate, buildings, roads, etc. Secondarily, we inventoried paths with a relatively low number of visitors.