Primjenjivost različitih modela regresije za procjenu volumena krupnog drva stabala hrasta kitnjaka (Quercus petraea (Matt.) Liebl.) u Bosni i Hercegovini

SummaryIn Bosnia and Herzegovina, there are tariff tables used for estimating the volume of sessile oak trees in high forests, which were created on the basis of two-entry volume tables for oak trees from the area of Germany, authored by Schwappach in 1905. There are indications that the application of the aforementioned tariffs in forest management practice results in certain differences in the estimated amount of merchantable wood volume compared to the real situation. The material for creation of volume tables was the data concerning the measurement of 2,413 model trees in different habitat and stand conditions. A large number of widely used regression models was tested to equalize the volume of merchantable wood volume as a dependent variable in terms of the diameter at breast height and height of the tree as independent variables. Regression models such as Schumacher-Hall and Spurr II provide satisfactory accuracy, that is, they can be used to estimate the merchantable wood volume of sessile oak trees in high forests (pure and mixed) in the territory of Bosnia and Herzegovina, with a permissible deviation. By introducing the third variable into the model, diameter at seven meters height, the accuracy of the tree volume estimation increases significantly, but due to the significant increase in the volume of work on collecting the necessary data, this model is not suitable for use in forest inventories.SažetakU Bosni i Hercegovini za procjenu volumena stabala hrasta u visokim šumama koriste se uređajne tarife, koje su izrađenene na temelju dvoulaznih volumnih tablica za hrast s područja Njemačke autora Schwappach iz 1905. godine. Postoje indicije da se primjenom navedenih tarifa u uređajnoj praksi dobivaju određene razlike u količini procijenjenog volumena krupnog drva u odnosu na stvarno stanje. Materijal za izradu volumnih tablica odnosno modela regresije predstavljali su podaci izmjere i izračuna stvarnog volumena drva 2.413 modelnih stabala u različitim stanišnim i sastojinskim uvjetima. Na osnovi raspodjele stabala po debljinskim stupnjevima možemo zaključiti da je relativno mali broj stabala koja su deblja od 70 cm, u ostalim debljinskim stupnjevima broj stabla veći je od 100, odnosno u intervalu od 111 do 316. Testirani su modeli koji imaju široku primjenu za izjednačenje volumena krupnog drva stabla kao zavisne varijable u ovisnosti o prsnom promjeru i visini stabla kao nezavisnim varijablama. Za usporedbu i analizu upotrebljivosti modela regresije korišten je veći broj kriterija (Srednja apsolutna greška, Korijen prosječne kvadratne pogreške, Koeficijent determinacije i Akaike informacijski kriterij). Uz navede kriterije, testirane su značajnosti razlika pomoću t-testa parova uzoraka između stvarnih i procijenjenih volumena krupnog drveta stabala te utvrđeni postoci odstupanja procijenjenih od stvarnih volumena, po debljinskim stupnjevima i ukupno. Modeli kao što su Schumacher-Hall i Spurr II daju zadovoljavajuću točnost, s obziron na to da su u pitanju općeniti modeli namijenjeni za procjenu volumena stabala na području cijele Bosne i Hercegovine. Uvođenjem u model i treće varijable, promjer debla na sedam metara visine, povećava se značajno točnost procjene volumena stabala. Zbog izmjere promjera na sedam metara visine povećava se značajno i količina rada na terenu na prikupljanju potrebnih podataka, pa ovaj model nije pogodan za primjenu u operativnim inventurama šuma. Uvođenjem visine baze krošnje stabla kao treće varijable, nije se povećala točnost procjene volumena stabla u odnosu na analizirane dvoulazne modele

Modul loma i modul elastičnosti drva omorike (Picea omorika Pančić/Purkyně) iz prirodnih sastojina

The paper presents the results of testing the bending stress of Serbian spruce wood from natural stands. In testing the samples, in addition to the modulus of rupture, the bending stress at the proportionality limit, the ratio between the stress at the proportionality limit and the modulus of rupture as well as the modulus of elasticity of wood were determined. The study included nine trees from natural stands, and a total of 261 samples were tested. Regression analysis determined the dependences of these mechanical properties on the annual ring width, the proportion of late wood and wood density, as well as the dependence of the modulus of elasticity on the modulus of rupture.U radu su prikazani rezultati ispitivanja naprezanja pri savijanju drva Pančićeve omorike podrijetlom iz prirodnih sastojina. Osim modula loma, pri ispitivanju uzoraka utvrđeni su i savojno naprezanje u točki proporcionalnosti, odnos čvrstoće na savijanje u točki proporcionalnosti i modula loma, kao i modul elastičnosti drva. Istraživanje je obuhvatilo devet stabala iz prirodnih sastojina, a ispitan je ukupno 261 uzorak. Regresijskom su analizom utvrđeni odnosi navedenih mehaničkih svojstava i širine goda, udjela kasnog drva i gustoće drva, kao i odnos modula elastičnosti i modula loma

First Dendroclimatological Insight into Austrian Pine (Pinus nigra Arnold) Climate-Growth Relationship in Belgrade Area, Serbia

In order to assess the impact of climate variations on Austrian pine forest in the Belgrade area, the radial growth of artificially-established Austrian pine trees and its dependence on temperature and precipitation was studied using dendroclimatological methods. The site is classified as Quercetum-frainetto cerris Rudski. Standard and residual chronologies were established and several common statistics were calculated. A dendroclimatic study was carried out using the correlation and response function analysis. The Pearson correlation coefficients between the chronology indices and 13 seasonal (3-month period) precipitation and temperature data were calculated for the period from 1959 to 2014. The applied response function analysis included 24 precipitation and temperature variables from October of the prior year to September of the current year. The results of the correlation analysis pointed out that there was a strong tendency towards a positive response to the summer and late summer/early autumn precipitation and a weak significant negative response to the spring and summer temperatures. Climate-growth relationships were further first studied using the response functions for the significant seasons that were detected from the correlation analysis and then for individual months from previous October to current September. These results also highlighted the findings that higher precipitation in the current summer months has a beneficial effect on the tree-ring width. The conducted correlation between the residual chronology and the Standardised Precipitation Evapotranspiration Index indicated that a high summer value of this drought index had a positive impact on the pine growth and reinforced the previously detected relevance of September as an important month for the Austrian pine growth. These preliminary results point out that some additional climate-Austrian pine growth studies (application of various tree-ring features, growth data with a much longer time span, more sites/stands, etc.) should be performed to obtain new and valuable knowledge important for the sustainable management of Austrian pine forests

Relationships Between Climatic Variables and Tree-Ring Width of Silver Fir (Abies alba Mill.) in Kozara National Park (Bosnia and Herzegovina)

Silver fir (Abies alba Mill.) is the most common conifer species in Bosnia and Herzegovina. The paper describes the development of a silver fir master tree-ring chronology from Kozara National Park and analyzes the influence of the climate conditions on tree-ring widths. The knowledge concerning the effect of climate on cambium activity and, as a result, on tree growth is of great importance for silviculture, which is particularly complex in terms of deterioration of health condition. Four sites were selected for sampling at Kozara National Park. At each sampling site, 15 dominant trees were drilled with Pressler’s increment borer at breast height. The development of chronology included three steps: i) cross-dating of a series of tree-ring width and checking of their quality using the COFECHA program, ii) data standardization in the ARSTAN program, and iii) master chronology development. Correlation analysis was performed in order to determine the links between tree-ring width and climate (primarily temperature and precipitation). In the 88-year-long master chronology, pointer years analysis identified five positive and nine negative years. Correlation analysis revealed that precipitation had stronger and more significant impact on silver fir radial growth, particularly at the beginning of the growing season, in April and May (r=0.175 and r=0.318, respectively), and in the crucial July−September period (r in the range of 0.143−0.222). The highest negative correlation coefficient with temperature was determined for September of the previous year (r=-0.282) and then for summer months (July and August) of the current year (r=-0.184 and r=-0.272, respectively). In addition, statistically significant correlation between radial growth and the Forestry Aridity Index was determined (r=-0.390). The results of tree-ring width climate analysis obtained in this study are in accordance with other studies carried out in Bosnia and Herzegovina and in the surrounding area

Usporedna analiza utjecaja klimatskih čimbenika na radijalni rast autohtonih vrsta borova (Pinus spp.) u središnjoj Bosni i Hercegovini

In central Bosnia and Herzegovina, in the Zavidovići-Teslić area, the study of the radial growth of Austrian and Scots pine (autochthonous pine species) trees was conducted using the dendrochronological method in order to identify the differences between the species in terms of the influence of climatic variables on the tree ring formation. Trees were sampled in five experimental areas or five sites. The first site had a Scots pine stand, while the second had an Austrian pine stand, and the other three sites had mixed stands of Scots and Austrian pine. Cross-dating was conducted using visual on-screen techniques of CDendro software and statistical methods using Cofecha software. The tree ring series were standardized using the Arstan program and cubic smoothing spline. It produced Scots pine regional chronology, 145 years long (1870-2014), and Austrian pine regional chronology, 180 years long (1835-2014). Correlation analysis of the relationship between the index of tree-ring width and precipitation and temperature in the characteristic periods of the year showed a negative effect of temperature (except in winter months) and a positive effect of precipitation on the tree ring formation. The statistically significant dependence of the tree-ring width index on the SPEI indices indicates a significant impact of moisture deficiency on the tree ring formation in the period from June to August (r = 0.33 in June, r = 0.45 in July and r = 0.47 in August) for Scots pine and in the period from June to September (r = 0.36 in June, r = 0.43 in July, r = 0.47 in August and r = 0.30 in September) for Austrian pine. The analysis of the relationship between climatic parameters and the chronologies of Scots and Austrian pine shows similar relationships between radial growth and climate but the influence of climate is somewhat more pronounced in Austrian pine. In the study area, the radial growth of both tree species is significantly determined by climate conditions. In other words, the chronology of these species has a good climatic signal, especially the drought signal in the summer months.U Zavidovićko - Teslićkom području, u središnjoj Bosni i Hercegovini, dendrokronološkom metodom je proučavan radijalni rast stabala crnog i bijelog bora, autohtonih vrsta u pomatranom području. Cilj je bio identifikacija razlika između spomenutih vrsta glede utjecaja klimatskih čimbenika. Uzorci su uzeti iz stabala s pet lokaliteta. Na prvom lokalitetu je sastojina bijelog bora, na drugom crnog bora, a na ostala tri lokaliteta su mješovite sastojine. Standardizacija serija širina godova (radijalnih prirasta) obavljena je primjenom Arstan programa. Dobivena je regionalna kronologija bijeloga bora dužine 145 godina (od 1870. do 2014.) i regionalna kronologija crnoga bora dužine 180 godina (od 1835. do 2014.). Ispitivanje zavisnosti između indeksa širine goda i oborina odnosno temperature u pojedinim karakterističnim periodima godine, pokazalo je negativan utjecaj temperature (osim u zimskim mjesecima) na formiranje goda i pozitivan utjecaj oborina. Statistički značajna zavisnost indeksa širine goda od SPEI indeksa ukazuje na značajan utjecaj nedostatka vlage u periodu lipanj – kolovoz (r = 0,33 u lipnju, r = 0,45 u srpnju i r = 0,47 u kolovozu) za bijeli bor i periodu lipanj - rujan (r = 0,36 u lipnju, r = 0,43 u srpanju, r = 0,47 u kolovozu i r = 0,30 u rujnu) za crni bor na formiranje godova. Analiza odnosa klimatskih parametara i formiranih kronologija bijeloga i crnoga bora pokazuje slične odnose između širine goda i klime, ali je utjecaj klimatskih čimbenika nešto više izražen kod crnog bora, kojemu više odgovaraju uvjeti staništa na promatranom području. U promatranom području radijalni prirast stabala obje vrste drveća značajno je uvjetovan klimatskim čimbenicima, odnosno kronologije navedenih vrsta imaju dobar klimatski signal, a posebno signal suše u ljetnim mjesecima

ANALIZA PLANOVA U ŠUMSKOPRIVREDNIM OSNOVAMA REPUBLIKE SRPSKE

Analiza planova gazdovanja šumama predstavlja četvrti rad i posljednji je dio ukupne analize kvalitetašumskoprivrednih osnova za šume u svojini Republike Srpske. Analizom su obuhvaćeni: plan sječa, planiskorišćavanja šuma, plan šumskouzgojnih radova, plan zaštite šuma i ekonomsko-finansijska analiza.Težište razmatranja bilo je na ekonomski vrijednijim šumama. Pokazalo se da planovi imaju samo formalnikarakter i da nisu upotrebljivi u praksi. Rad je baziran na podacima iz devet šumskoprivrednih osnova

ANALIZA I OCJENA GAZDOVANJA ŠUMAMA: Kriti

Analiza i ocjena gazdovanja šumama u proteklom ur

VARIJABILITET TAKSACIONIH ELEMENATA STABLA I PLANIRANJE VELIČINE UZORKA ZA INVENTURU ČISTIH SASTOJINA HRASTA KITNJAKA

Šumske sastojine kao specifični skupovi, sa aspekta statistike i dendrometrije posmatraju se kaoskupovi stabala ili kao skupovi elementarnih površina različitog oblika i veličine. Problem planiranjaveličine uzorka za taksacionu procjenu šuma, svodi se prvenstveno na istraživanje varijabilitetavažnijih taksacionih elemenata u našim šumama. Kada su u pitanju zrele sastojine hrasta kitnjakaodnosno sastojine u kojima je potrebno započeti sa procesom obnove, za potrebe planiranja gazdovanjaneophodna je visoka tačnost procjene zapremine. Potrebna je znatno veća tačnost procjenezapremine u odnosu na srednjedobne i mlade sastojine. Polazeći od podataka za 20 čistih sastojinahrasta kitnjaka, metodom višestruke regresije dobijen je model za procijenu koeficijenta varijacijezapremine stabla na osnovu broja stabala i temeljnice sastojine. Dobijeni model omogućava dase za traženu preciznost procjene u zrelim sastojinama hrasta kitnjaka planira potrebna veličinauzorka za inventuru sastojine

Spatial Structure of Uneven-Aged Stands of Fir and Beech on the Borja Mountain (Bosnia and Herzegovina)

In the territory of Bosnia and Herzegovina, uneven-aged stands of fir and beech are very important from the economic and ecological points of view. A major lack of information on the simple structure of stands is that it cannot be used to draw valid conclusions about the spatial distribution of woody species and about the position and dimensions of trees, and this is one of the bases for the sustainable management of mixed and uneven-aged forests. In four mixed uneven-aged fir and beech stands and one pure fir stand on Mt Borja, the basic elements of tree growth were measured and the data needed to determine the indicators of the spatial stand structure were determined. According to the Clark–Evans aggregation index, there is a tendency towards a uniform spatial distribution of trees in the stand in the case when all trees are observed. When only fir trees are observed, it is evident that there is a tendency to group fir trees in the stand. The diameter differentiation index shows that there is average tree diameter differentiation on all sample plots. The determined values of the Weber height competition index by stands are approximately the same, that is, it can be stated that there is no significant difference between stands in terms of competition between trees as regards the vertical structure of stands