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ŠUMARSKI LIST 11-12/2019 str. 58     <-- 58 -->        PDF

During our movement along the path, we inventoried only damaged trees with a DBH exceeding 10 cm that were inside a 2-m wide area on either side of the path and required management measures (salvage cutting, pruning, sanitation cutting, thinning, etc.). Visibly healthy trees were not considered. When a damaged tree was found, we recorded the GPS location of the tree and the number of the point in a consecutive manner, which represented an identification number to which all other data regarding the damaged tree were referenced. For the damaged tree, we measured its DBH and recorded the tree species and damaging factor / causal agent. We recorded all damaging factors for each single tree. Additionally, a management measure was suggested and recorded.
All attribute data were recorded on paper, digitized (copied into a Microsoft Excel table) and linked together with GPS data (tree location). In this way, the data became geo-referenced.
The UFMO method was designed to focus on areas with management priority in the urban forest. Therefore, urban forest health surveys with the UFMO method usually include paths with a relatively high number of visitors and forest areas that are close to real estate, buildings, roads, etc. This was generally true also for our study in MOL. Additionally, we chose paths that were closer to the inventoried ISM plots, which made the ISM and UFMO methods spatially comparable. Furthermore, we wanted to make both methods comparable in terms of time; therefore, we took care to carry out both methods in approximately the same time.
Monitoring vs. Surveying – Monitoring : pregledi
In this paper monitoring refers to assessing a portion of a population to determine the condition of the resource, especially the change in the condition over time, and surveying refers to a procedure conducted over a defined period to determine the characteristics of a population in a defined area at the time of the survey. Monitoring is performed repeatedly on the same sampling plots, whereas surveying is usually performed on the same sampling plot only once. The ISM method is a monitoring method, and the UFMO method is a surveying method. The UFMO method uses non-linear transects as sampling plots. Non-linear transects can be used in a monitoring method when they are chosen randomly, and the assessment procedure is repeated in a defined time. Unlike the ISM method, the UFMO method does not use a representative sample and should not be used to make inferences regarding the entire population. In our study, the ISM method was used as the survey method even though it is basically the monitoring method.
Data analysis – Analiza podataka
The data analysis was focused on comparing the ISM and UFMO methods, i.e. a comparison of the performance between ISM and the UFMO method. As the methods are not directly comparable, special care was dedicated to finding appropriate and comparable measures. The performance was measured by the time used to assess a certain area (time/area), the amount of data recorded, the number of damaging agents determined, the number of trees assessed, the number of standing dead trees recorded, and the number of management measures suggested. Simple linear regression along with the coefficient of determination (R2) were used for explaining the possible correlation between the track length and the duration of the survey, between the track length and the number of management measures, and between the duration of the survey and the number of management measures. The significance of the correlation (p-value) was calculated at the 95% confidence level.
The data gathered during this study are freely available at PANGAEA® (Ogris et al., 2015).
We assessed the crown condition and the damaging agents on 15 ISM plots. The performance time for the ISM and UFMO methods was 17.8 min/a and 3.28 min/a, respectively. According to the time/area performance measure, the UFMO method performed 5.4 times better than the ISM method (Table 1). The ISM method recorded 30% more data than the UFMO method in approximately the same time. The density of gathered data was 7.1 times higher for the ISM method. The UFMO method recorded