Estimating the accuracy of volume tables and volume equations for Silver fir

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

Using Lidar Data to Analyse Sinkhole Characteristics Relevant for Understory Vegetation under Forest Cover\u2014Case Study of a High Karst Area in the Dinaric Mountains

In this article, we investigate the potential for detection and characterization of sinkholes under dense forest cover by using airborne laser scanning data. Laser pulse returns from the ground provide important data for the estimation of digital elevation model (DEM), which can be used for further processing. The main objectives of this study were to map and determine the geomorphometric characteristics of a large number of sinkholes and to investigate the correlations between geomorphology and vegetation in areas with such characteristics. The selected study area has very low anthropogenic influences and is particularly suitable for studying undisturbed karst sinkholes. The information extracted from this study regarding the shapes and depths of sinkholes show significant directionality for both orientation of sinkholes and their distribution over the area. Furthermore, significant differences in vegetation diversity and composition occur inside and outside the sinkholes, which indicates their presence has important ecological impacts

Determining Bulk Factors for Three Subsoils Used in Forest Engineering in Slovenia

In Slovenia, torrent areas and forest roads are being regulated and built mostly in steep, erosion-prone areas. In addition to the geometry of extrapolated works, calculating bulk factors is key for estimating haulage masses. We have determined bulk factors for compact carbonate rock, mixed soil, and carbonate deposits. Each construction site was recorded with an unmanned aerial vehicle (UAV) before the excavation and after every 4±2 m3 of excavated material. The average point cloud density was 9535 points/m2. We processed the point clouds from each construction site and determined the difference in volume between the volume of excavated area and the volume of deposited material. The average bulk factor for compact carbonate rock is 1.42, 1.20 for mixed soil and 1.15 for carbonate deposits (calculated for fully loaded eight-wheeled truck). The calculated bulk factors for soils and carbonate deposits match with the already established values, while the factor for compact rock is 20% lower than the factor currently in use by the Slovenian forest engineers

Ocena sprememb organske snovi v tleh na ploskvi Brdo glede na različne scenarije podnebnih sprememb z uporabo modela Yasso07

The forest soil can act as an important sink for CO2 and in that respect also appears in the national Kyoto reports, where a distinction is made between carbon accumulated in litter and organic soil horizons and carbon accumulated in mineral soil layers. There is a multitude of dynamic models of organic carbon (Corg) change in the soil particularly due to different environmental and anthropogenic factors. The purpose of this paper is the Yasso07 model application on the “Brdo” plot, which is part of the ICP Forest Level II plots of Slovenia. The Yasso07 model describes the decomposition of organic matter in the forest soil by dividing litter inputs into different components with varying decomposition rates. Here, the temporal change of soil Corg in various scenarios of future climate change (increase in air temperature, change in precipitation) was predicted. The difference between the measured amount and the model-predicted amount of Corg in the soil for the current climate on the Brdo plot is 6.4 t C ha-1 (88.6 t C ha-1 measured vs. 95.0 t C ha-1 predicted). Taking into consideration the climate change scenarios for Slovenia, Corg stock is expected to decrease in the future according to Yasso07 projections in all scenarios of climate change. The estimate of 100-year decrease of Corg is the largest for scenario, when large increase of both temperature and precipitation is expected (18.2%) and smallest when small temperature increase and precipitation decrease are predicted (9.3%). Assuming stable litter input, larger influence on Corg decrease was predicted for the temperature change compared to precipitation change. However, many uncertainties are included in model estimates ranging from litter input estimates, climate change uncertainties, climate-litter production feedbacks, starting value estimates, etc. The determination of the uncertainty of model calculations is a requirement for conducting simulations and their interpretation

Pedotransfer funkcije za procjenu gustoće šumskih tala

The data of 45 soil profiles from a 16 × 16 km grid across Slo­venia was analysed to develop a local pedotransfer function (PTF) for bulk den­sity (.b) estimation. In total, 106 soil horizons were considered. Concentration of organic carbon (OC) was found to be well correlated (r = -0.861, p < 0.001) with .b. Two separate line segments were fitted to the data, which was partitio­ned into two intervals, based on OC content (below 36.0 g/kg and above 36.0 g/kg). Nearly 80 % of the variability in .b is explained with segmented re­gression. The local PTF was compared with published PTFs and four valida­tions indices (MPE, SDPE, RMSPE and R2) confirmed the highest prediction quality of the local PTF. The differences of carbon stock (Cpool) estimation, based on usage of different PTFs could be higher than 160 t OC per hectare. Predic­tion of carbon stocks could be substantially improved by calibration of the mo­dels coefficients with data stratified according to each unique soil type.S obzirom na vremensku zahtjevnost i veliku količinu rada po­trebnog za uzorkovanja i analize kemijskih i fizikalnih svojstava šumskih tala, razvoj alternativnih metoda je vrlo važan. Korištenjem pedotransfer funkcija (PTF), znanstvenici koji se bave proučavanjem tala mogu dobiti informaciju o najvažnijim svojstvima tala koja je inače teško (skupo ili vremenski zahtjevno) dobiti. PTF se mogu definirati kao statistički modeli za predviđanje fizikalnih (gustoća, hidraulička svojstva, itd.) i kemijskih (npr. kapacitet za izmjenu ka­tiona) svojstava tla iz drugih, dostupnijih ili rutinski analiziranih svojstava. Cilj ovog rada je bio razviti lokalnu PTF za procjenu gustoće mineralnog di­jela šumskih tala Slovenije. Na osnovi literature, hipoteza je bila da (1) gustoća snažno korelira s konce4ntracijom organskog ugljika (OC) i (2) lokalna PTF daje bolčje vrijednosti od objavljenih pedotransfer funkcija. Podaci 45 profila tla s bioindikacijske 16 x 16 km mreže u Sloveniji su anali­zirani s ciljem razvijanja lokalne pedotransfer funkcije za procjenu gustoće tla. Ukupno je obrađeno 106 profila tla. Uzorci za procjenu gustoće tla uzeti su u pet ponavljanja korištenjem metal­nih O-prstenova zapremine 5 cm3. U laboratoriju su uzorci tla osušeni na 105 °C i izvagani za daljnje kemijske i fizikalne analize. Korištene su sljedeće analitičke metode: pH je određen u KCl prema ISO 10390 na automatskom ph-metru Me­trohm Titrino, sadržaj C i N je određen prema ISO 10694 i/ili 13878 na elemen­tarnom analizatoru Leco CNS-2000, karbonati prema ISO 10693 Scheiblerovim kalcimetrom a mehanički nsastav tla prema ISO 11277 sedimentnom metodom i pipetom prema Köhnu. Jednostavna i multipla regresija korištene su za predviđanje .b korištenjem različitih zavisnih varijabla, a testirani su također i regresijski modeli sa seg­mentnim odnosima. Koncentracija organskog ugljika (OC) dobro korelira (r = -0.861, p < 0.001) s gustoćom tla. Dva odvojena segmenta linije izjednačenja uklopljeni su u poda­tke koji su razdijeljeni u dva intervala prema sadržaju OC (ispod i iznad 36,0 g/kg). Gotovo 80 % varijabiliteta gustoće tla objašnjeno je segmentnom re­gresijom (Slika 4.). Lokalna pedotransfer funkcija uspoređena je s objavljenim funkcijama a če­tiri indeksa validacije (MPE, SDPE, RMSPE and R2) potvrdila su najveću kvali­tetu predviđanja lokalne pedotransfer funkcije (Slika 5.). Razlike u procjeni zalihe ugljika u tlu (Cpool) različitih pedotransfer funkcija bile su veće od 160 t/ha (Tablica 4.). Predviđanje zaliha ugljika moglo bi biti značajno unaprijeđeno kalibracijom koeficijenata u modelima pomoću podataka razvrstanih prema vrsti tla