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Čavlović, J., Božić, M., 2008: Nacionalna inventura šuma u Hrvatskoj – Metode terenskog prikupljanja podataka, Šumarski fakultet Sveučilišta u Zagrebu, 146 str., Zagreb
Čavlović, J., 2010: Prva nacionalna inventura šuma Republike Hrvatske, Šumarski fakultet Sveučilišta u Zagrebu, 300 str., Zagreb
Elzinga, C., R.C. Shearer, G. Elzinga, 2005: Observer variation in tree diameter measurements, Western Journal of Applied Forestry, Vol. 20. (2): 134-137., Bethesda
Husch, B., T.W. Beers, J.A. Kershaw Jr., 2003: Forestmensuration (4th ed.), John Wiley&Sons, 443 str., New York
Johnson, J. E., Haag, C. L., 1985: Reliability of height and diameter remeasurements on Red pine (Pinus resinosa Ait.) seedlings, Tree Planter’s Notes, Vol. 36, (2): 27-29., Washington, D.C.
Keller, M., 2005: Schweizerisches Landesforstinventar, Forschungsanstalt für Wald, Schnee und Landschaft, 393 str., Birmensdorf
Kitahara, F., N. Mizoue, S.Yoshida, 2010: Effects of training for inexperienced surveyors on data quality of tree diameter and height measurements. Silva Fennica 44(4): 657–667, Helsinki
Laar, A. van, A. Akҫa, 2007: Forest  mensuration, Springer Science & Business Media, 383 str., Heidelberg
Loetsch, F., F. Zőhrer, K.E. Haller, 1973: Forest Inventory, BLV Verlagsgesellchaft, 436 str., Munich
Melson, S., D. Azuma., J.S. Fried, 2002: A first look at measurement error on FIA plots using blind plots in the Pacific Northwest, U: McRoberts, R.E., G.A. Reams, P.C. Van Deusen, J.W. Moser, (ur.), Proceedings of the Third Annual Forest Inventory and Analysis Symposium, Gen. Tech. Rep. NC-230. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Research Station, str. 11-20, Traverse City
Omule, S.A.Y., 1980: Personal bias in forest measurements, The Forestry Chronicle, Vol. 56. 222-224., Vancouver, B.C.
Pranjić, A., N. Lukić, 1997: Izmjera šuma, Šumarski fakultet Sveučilišta u Zagrebu, 405 str., Zagreb
Pravilnik o doznaci stabala. Narodne novine (17/2015), Službeni list Republike Hrvatske
Prodan, M., 1965: Holzmesslehre, J.D. Sauerlander’s Verlag, 659 str., Frankfurt
TIBCO Software Inc., 2018: Statistica (data analysis software system), version 13.
Ugrenović, A., 1950: Tehnologija drveta, Nakladni zavod Hrvatske, 502 str., Zagreb
A tree diameter at breast height (dbh) is a basic variable measured in forest inventory. Generally, it is measured with calipers whose arms have to be perpendicular to the beam. Therefore, caliper has to be rectified before measurement. Measurement should be performed in the way that caliper itself is perpendicular to the tree stem with arms and beam touching the tree without applying too much pressure to caliper arms. Measurer mistakes and failing to follow standard measurement procedures lead to errors that reflect in all inventory results (basal area, stand volume). Experience gathered while working with students and colleagues in practice, showed that measurement procedures sometimes significantly depart from required. Therefore, the aim of this research was to quantify and analyze known and observed dbh measurement errors.
For that purpose two sites in Zagreb Training and Forest research center were selected: one site in area of lowland oak and hornbeam forest stand and another in mountain area with mixed fir and beech forest. Total 282 trees (74 Pedunculate oak, 56 Common hornbeam, 76 Silver fir and 76 Common beech) in wide diameter range were measured. (Table 1). All selected trees were marked with a number before measurement.
On both research plots three measurers performed following diameter measurements using Haglof Mantax caliper: crosswise diameters at self-estimated breast height with (1a, 1b), crosswise diameters at marked breast height (2a, 2b), 10 cm above (3a) and 10 cm under the marked breast height (3b), at marked breast height point with caliper beam held apart from tree and normal pressure on the caliper arms (4a) and higher pressure on the caliper arms (4b) and caliper beam on marked point with caliper tips facing up (5a). Measurement group consisted of two measurers. One measurer preformed measurement and other was writing the data. Since measurers height can affect the placement of the calipers on the tree, so position of breast height of 1,3m was determined using measuring tape before beginning of measurement for each measurer. Marking of breast height point on the tree was made after measurement with self-estimated breast height. Collected data were analyzed using t-test and ANOVA with 0,05 significance level.
Results show that average differences between two crosswise diameter measurements at self estimated breast height are statistically significant for hornbeam (average difference 1 cm) and beech (average 1,7 cm). Fir and oak had less differences (up to 0,7cm) that were not proven statistically significant. (Table 2).
At marked breast height differences of crosswise measurements are as well statistically significant for hornbeam and beech. (Table 3). Comparison between average diameter difference at self-estimated