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Na dveh raziskovalnih hektarskih ploskvah na Pokljuki so v letih 2008 in 2009 izvedli polno izmero. Na podlagi premera dreves v prsni višini, premera drevesna 7 metrih ter višin so s pomočjo volumenskih funkcij - tarif, dvovhodnih deblovnic in trovhodnih volumenskih funkcij, izračunali lesno zalogo na ploskvah. Najnatančnejše so bile trovhodne volumnenske funkcije, katere upoštevajo vse tri parametre, najmanj pa tarife, pri katerih je bil volumen izračunan le na podlagi premerov dreves. Na raziskovalnih ploskvah so izračunali za 7 % oziroma 10 % višje vrednosti lesnih zalog, če so namesto trovhodnih volumenskih funkcij, uporabili eno-parametrske tarife. In the years 2008 and 2009 a full measurement of two research plots, a hectareeach, was performed on the Pokljuka Plain. On the basis of the breast height diameters of trees, the diameters at 7 m tree height, and the full heights of trees, the growing stock of the two plots was calculated, using tariff functions - two parametric volume functions and three parametric volume functions. The most accurate were the three parametric volume functions that take into account all three measures, whereas the least accurate were thetariffs which use only the diameters of the trees to calculate the tree volume. On research plots, up to 7 % and 10 % higher values of growing stock were calculated when one parametric tariff functions were used instead of three parametric volume functions.

Primerjali smo postopke za ocenjevanje volumna debeljadi jelke na podlagi Huberjevega, Smalianovega in Newtonovega obrazca. Podatke za primerjavo smo dobili z interpolacijo kubičnih zlepkov na podlagi merjenja posekanih dreves. Newtonov in Huberjev postopek sta bila najnatančnejša pri ocenjevanju volumnovstarih jelk (starost do 200 let, povprečni premer 59 cm). Na podlagi izračunanih volumnov smo ocenjevali volumne stoječih dreves v sklopu gozdne inventure. Slovenske Čoklove tarife (1959) so se kljub svoji preprosti zasnovi izkazale s sprejemljivo natančnostjo (povprečno odstopanje v odstotkih od povprečnega volumna < 1 %, R2=0.87). Delež pojasnjene variabilnosti volumnov dreves se je povečal za 5 % pri dvovhodnih deblovnicah in za 11 % pri triparametrskih volumenskih funkcijah. Comparisons of stem volume estimation techniques were performed based on equations of Huber, Smalian and Newton, and a cubic spline interpolation of points along the silver fir tree stems. Results indicate that Newton`s and Huber`s equations were the most accurate in determining volumes of old silver fir trees (age up to 200 years and average dbh 59 cm). The obtained tree volumes were the basis for the standing timber estimation in the forest inventory. Despite their rather simple structure, the Slovene Čokl (1959) tariff functions proved to be sufficiently accurate (average residual in percentage of the mean volume < 1%, R2=0.87). The proportion of the individualtree volume variance explained increased by 5 % for standard two-entry volume tables and by 11% for three-parameter volume functions.

Primerjali smo različne volumenske funkcije za ocenjevanje volumnov dreves. S pomočjo sekcijskih meritev (Newtonova metoda) smo izračunali prave ocene volumnov dreves 88 posekanih smrek na Pokljuki. Te smo uporabili za izdelavo regionalnih trovhodnih volumenskih funkcij, (dvovhodnih) deblovnic in tarif. Standardna napaka ocene povprečne vrednosti volumna drevesa je najmanjša pri trovhodnih volumenskih funkcijah (5,0 %), nato pri deblovnicah (11,7 %) in največja pri tarifah (15,1 %). Zanesljivost in uporabnost izdelanih regionalnih ter drugih volumenskih funkcij smo preverili na dveh hektarskih raziskovalnih ploskvah. Ugotovili smo, da s prirejenimi nemškimi deblovnicami smrekam določimo previsoke volumne. Ker volumne iz teh deblovnic uporabljamo tudi pri določanju prirejenih tarif na Slovenskem, je s takim postopkom določen tarifni razred z vsaj za 5 % previsokimi volumni dreves. Various volume functions used for tree volume estimations were compared by the authors. Using section measurements (Newtonʼs method), they calculated the real tree volumes of 88 felled spruce trees on the Pokljuka plateau. The real tree volumes were used to form regional three-entry volume functions, (two-entry) volume tables, and tariff functions. The standard error of the average tree volume estimation is the lowest for three-entry volume functions (5.0%), then for volume tables (11.7%), and the highest for tariffs (15.1%). The reliability and applicability of the developed regional and other volume functions was verified on two one-hectare research plots. It was established that by applying the adapted German volume tables, the measured spruce volumes were too high. As the volumes measured in this manner are used when determining the adapted tariffs in Slovenia, this procedure results in a tariff class of at least 5% too high tree volumes.

Primerjali smo postopke za ocenjevanje volumna debeljadi jelke na podlagi Huberjevega, Smalianovega in Newtonovega obrazca. Podatke za primerjavo smo dobili z interpolacijo kubičnih zlepkov na podlagi merjenja posekanih dreves. Newtonov in Huberjev postopek sta bila najnatančnejša pri ocenjevanju volumnovstarih jelk (starost do 200 let, povprečni premer 59 cm). Na podlagi izračunanih volumnov smo ocenjevali volumne stoječih dreves v sklopu gozdne inventure. Slovenske Čoklove tarife (1959) so se kljub svoji preprosti zasnovi izkazale s sprejemljivo natančnostjo (povprečno odstopanje v odstotkih od povprečnega volumna < 1 %, R2=0.87). Delež pojasnjene variabilnosti volumnov dreves se je povečal za 5 % pri dvovhodnih deblovnicah in za 11 % pri triparametrskih volumenskih funkcijah. Comparisons of stem volume estimation techniques were performed based on equations of Huber, Smalian and Newton, and a cubic spline interpolation of points along the silver fir tree stems. Results indicate that Newton`s and Huber`s equations were the most accurate in determining volumes of old silver fir trees (age up to 200 years and average dbh 59 cm). The obtained tree volumes were the basis for the standing timber estimation in the forest inventory. Despite their rather simple structure, the Slovene Čokl (1959) tariff functions proved to be sufficiently accurate (average residual in percentage of the mean volume < 1%, R2=0.87). The proportion of the individualtree volume variance explained increased by 5 % for standard two-entry volume tables and by 11% for three-parameter volume functions.

Za ugotavljanje lesne zaloge sestojev v Sloveniji uporabljamo enovhodne volumenske funkcije - prilagojene enotne francoske (PEF) tarife. Namen disertacije je ugotoviti, kako zanesljive so enovhodne volumenske funkcije za ugotavljanje lesne zaloge sestojev, in raziskati možnosti njihove izboljšave sstratifikacijo. Na podlagi ocene pravega volumna dreves (vn), izraunanega s pomojo sekcijskih meritev (Newtonov obrazec), smo za drevesne vrste smreko, jelko in bukev izdelali regionalne trovhodne (prsni premer (d), višina drevesa(h) in premer na 7 metrih višine (d7)), dvovhodne (d in h) in lokalne enovhodne (d) volumenske funkcije (tarife) ter preverili njihovo zanesljivost.Na primeru vzornih ploskev v dveh GGE smo drevesom izmerili vhodne parametre d, h in d7 in s pomojo regionalnih trovhodnih volumenskih funkcij izraunali referenne volumne dreves (vr). Analizirali smo vpliv bonitete rastiša, razvojne faze, drevesne vrste in vpliv socialnega položaja na zanesljivost ocene volumna dreves. Iz referennih volumnov dreves smo izraunali regionalne dvovhodne volumenske funkcije (d in h). Z njimi smo izraunali volumne dreves (vrr) in za posamezne stratume (drevesna vrsta, razvojna faza, rastiše) izraunali lokalne tarife (d). Preverili smo zanesljivost treh metod uporabe tarif. Po sedaj izbranih PEF tarifah ocena povprenega volumna drevesa odstopa od referenne povpreno za -5,7 % (-16,7 do e vrsto in razred PEF tarif izberemo optimalno, na podlagi lokalne tar19,5 %). In Slovenia one parametrical volume functions, adapted uniform French (AUF) tariffs, are used in order to determine stands growing stock. The purpose of the dissertation is to establish the reliability of tariffs for estimating stands growing stock and to investigate the possibilities of their improvementwith stratification. On the basis of true tree volume estimates (vn), calculated by means of section measurements (Newton method) regional three parametrical (diameter (d), tree height (h), diameter at 7 m tree height(d7)), regional two parametrical (d and h), and local one parametrical (d) volume functions (tariffs) were created for the tree species of spruce, fir and beech. The reliability of the functions was also tested. Trees at sampling plots in two forest units were measured in terms of dendrometric parameters d, h, d7 and later reference tree volumes (vr) were calculated by means of regional three parametric volume functions. The influence of site condition, developmental stage, tree species and height class on the reliability of tree volume estimate was analyzed. From reference tree volumes regional two parametrical volume functions (d and h) were calculated for both locations and all three tree species. They were further used to calculate regional reference tree volumes (vrr) and local tariffs (d) for individual strata (tree species, developmental stage, site). The reliability of three tariff application methods (existing, optimally selected and local tariffs) was examined. According to the existing AUF tariffs the mean tree volume estimate deviates from the reference by -5.7 % on average (from -16.7 to 19.5 %). According to the optimally selected AUF tariffs the mean tree volume estimate deviates from the reference by 0.1 % on average (from -0.8 to 2.2 %).On the other hand the mean tree volume estimate according to the local tariffs deviates from the reference by -0.1 % on average (from -0.3 to 0.2 %).Tariffs are therefore reliable enough for calculating growing stock estimates if they are suitably selected for a homogenous site stratum. The existing estimate of biomass quantity is unreliable due to its grounds in unreliable growing stock estimates and unconfirmed conversion/expansion factors.