Performance Analysis of Log Extraction by a Small Shovel Operation in Steep Forests of South Korea

In South Korea, logs for low-value products, such as pulpwood and fuelwood, are primarily extracted from harvest sites and transported to roadside or landing areas using small shovels. Previous studies on log extraction, however, have focused on cable yarding operations with the goal of improving productivity on steep slopes and inaccessible sites, leaving small-shovel operations relatively unexamined. Therefore, the main objectives were to determine small-shovel extraction productivity and costs and to evaluate the impact of related variables on productivity. In addition, we developed a model to estimate productivity under various site conditions. The study took place in 30 case study areas; each area has trees with stems at a diameter at breast height ranging from 18 to 32 cm and a steep slope (greater than 15%). The areas ranged from 241 to 1129 trees per hectare, with conifer, deciduous, and mixed stands. Small-shovel drives ranged from 36 to 72 m per extraction cycle from stump to landing. The results indicated that the mean extraction productivity of small-shovel operations ranged between 2.44 to 9.85 m3 per scheduled machine hour (including all delays). At the forest level, the estimated average stump-to-forest road log production costs were US $4.37 to 17.66/m3. Small-shovel productivity was significantly correlated with stem size (diameter at breast height and tree volume) and total travelled distance (TTD). However, a Pearson’s correlation analysis indicated that stand density and slope did not have a significant effect on productivity. Our findings provide insights into how stem size and TTD influence small shovel performance and the predictive ability of productivity. Further, this information may be a valuable asset to forest planners and managers.

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Influence of Progeny and Initial Stand Density on the Relationship between Diameter at Breast Height and Knot Diameter of Picea abies

Scandinavian Journal of Forest Research ◽

10.1080/02827589950154177 ◽

1999 ◽

Vol 14 (5) ◽

pp. 470-480 ◽

Cited By ~ 20

Author(s):

Geir Isak Vestøl ◽

Francis Colin ◽

Michel Loubère

Keyword(s):

Picea Abies ◽

Stand Density ◽

Diameter At Breast Height ◽

Breast Height ◽

The Relationship

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PENAKSIRAN VOLUME POHON KOMERSIL MELALUI METODE PENARIKAN ACAK BERLAPIS (STRATIFIED RANDOM SAMPLING) BERDASARKAN KELAS LERENG DAN KERAPATAN TEGAKAN DI PT. LIMBANG GANECA

ULIN Jurnal Hutan Tropis ◽

10.32522/u-jht.v2i2.1467 ◽

2018 ◽

Vol 2 (2) ◽

Author(s):

Gunawan Wibisono

Keyword(s):

Random Sampling ◽

Stand Density ◽

Stratified Random Sampling ◽

Class Iii ◽

Diameter At Breast Height ◽

Breast Height ◽

Two Factors ◽

Interaction Factors ◽

Vegetation Maps ◽

Slope Class

This study aims to estimate the volume of commercial trees at PT. Limbang Ganeca based on Stratified Random Sampling carried out on the RKL VII area of the HPH with an area of 16,101 hectares with a forested area of 15,215 hectares. The area of the study area is 76.08 hectares which is divided into strata based on the slope class and stand density. Based on the results of stratification of topographic maps and vegetation maps, there is a combination of slope I class, slope II class, slope class III and three forest stratum with a combination of 9 forest strata. From this combination the diameter at breast height is measured to assess the volume of the tree.Based on the results of data analysis, slope class factors can be used in estimating volume, while stand density and interaction factors for these two factors cannot be used in estimating tree volume. From the results of measuring the diameter at breast height and calculating tree volume, the average volume of the area was 109,9898 m3 / hectare or around 108,309 to 111,487 m3 / hectare. While the overall volume of the RKL VII area ranges from 1,647,950,462 to 1,696,304,584 m3.

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Planting density and tree-size relations in coast Douglas-fir

Canadian Journal of Forest Research ◽

10.1139/x97-190 ◽

1998 ◽

Vol 28 (1) ◽

pp. 74-78 ◽

Cited By ~ 18

Author(s):

William Scott ◽

Rodney Meade ◽

Richard Leon ◽

David Hyink ◽

Richard Miller

Keyword(s):

Tree Growth ◽

Stand Density ◽

Average Diameter ◽

Douglas Fir ◽

Planting Density ◽

Practical Significance ◽

Average Height ◽

Diameter At Breast Height ◽

Breast Height ◽

Initial Spacing

Test plantations were established in western Washington and Oregon to compare tree growth at six initial planting densities ranging from 300 to 2960 trees/ha (120 to 1200/acre). A size-density relation was visually apparent 3 to 4 years after planting. Inventory data from the oldest 11 trials (5 or 6 years after planting) showed that initial spacing strongly influenced early growth of coast Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii). Average height and diameter at breast height were progressively larger as planting density increased; at the widest spacing (lowest stand density), average height was 75% and average diameter at breast height was 67% of that at the closest spacing. We have no firm explanation for the early faster tree growth at close spacings. Trees planted at 2960 trees/ha (1200 trees/acre) attained breast height (1.3 m) 2 years earlier than trees planted at a density of 300/ha (120/acre). This finding has practical significance to current efforts to achieve early establishment of plantations.

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The Influence of Cross-Section Thickness on Diameter at Breast Height Estimation from Point Cloud

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi9090495 ◽

2020 ◽

Vol 9 (9) ◽

pp. 495

Author(s):

Milan Koreň ◽

Milan Hunčaga ◽

Juliana Chudá ◽

Martin Mokroš ◽

Peter Surový

Keyword(s):

Cross Section ◽

Cross Sections ◽

Point Cloud ◽

Point Clouds ◽

Estimation Accuracy ◽

Circle Fitting ◽

Section Thickness ◽

Diameter At Breast Height ◽

Breast Height ◽

The Impact

Circle-fitting methods are commonly used to estimate diameter at breast height (DBH) of trees from horizontal cross-section of point clouds. In this paper, we addressed the problem of cross-section thickness optimization regarding DBH estimation bias and accuracy. DBH of 121 European beeches (Fagus sylvatica L.) and 43 Sessile oaks (Quercus petraea (Matt.) Liebl.) was estimated from cross-sections with thicknesses ranging from 1 to 100 cm. The impact of cross-section thickness on the bias, standard error, and accuracy of DBH estimation was statistically significant. However, the biases, standard errors, and accuracies of DBH estimation were not significantly different among 1–10-cm cross-sections, except for oak DBH estimation accuracy from an 8-cm cross-section. DBH estimations from 10–100-cm cross-sections were considerably different. These results provide insight to the influence of cross-section thickness on DBH estimation by circle-fitting methods, which is beneficial for point cloud data acquisition planning and processing. The optimal setting of cross-section thickness facilitates point cloud processing and DBH estimation by circle-fitting algorithms.

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DIAMETER AT BREAST HEIGHT ESTIMATED FROM STUMPS IN Quercus frainetto IN THE REGION OF EVROS IN NORTHEASTERN GREECE

CERNE ◽

10.1590/01047760201622032193 ◽

2016 ◽

Vol 22 (3) ◽

pp. 337-344 ◽

Cited By ~ 3

Author(s):

Elias Milios ◽

Kyriaki G Kitikidou ◽

Vasileios Dalakouras ◽

Elias Pipinis

Keyword(s):

Quadratic Model ◽

Illegal Logging ◽

Mixed Stands ◽

Diameter At Breast Height ◽

Breast Height ◽

Quercus Frainetto

ABSTRACT For foresters, it is sometimes required to estimate the diameter at breast height of tree that has been cut, though it is often only the stump that is available as an indicator of size, after illegal logging and quick removal of the cut trees from the forest. In this study, equations for predicting the diameter at breast height, were fit specifically for Quercus frainetto in the region of Evros in northeastern Greece. The selected equations (quadratic model) were, where is the estimated diameter at breast height d (cm), and dst is the measured diameter at stump height (cm); for pure stands (R2 = 0.94); for mixed stands (R2 = 0.92); for the whole forest (R2 = 0.94).

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The Impact of Weather and Slope Conditions on the Productivity, Cost, and GHG Emissions of a Ground-Based Harvesting Operation in Mountain Hardwoods

Forests ◽

10.3390/f12121612 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1612

Author(s):

Sättar Ezzati ◽

Farzam Tavankar ◽

Mohammad Reza Ghaffariyan ◽

Rachele Venanzi ◽

Francesco Latterini ◽

...

Keyword(s):

Ghg Emissions ◽

Timber Harvesting ◽

Operating Conditions ◽

Production Costs ◽

Cost Models ◽

Mixed Stands ◽

Average Delay ◽

Productivity Cost ◽

Steep Slopes ◽

The Impact

Mountainous hardwood mixed stands offer challenges to timber harvesting operations in practice, including a harsh climate, variable topography, steep terrain, and large-sized timbers. This paper aims to develop productivity and cost models for a mountain-ground-based harvesting operation across the terrain (e.g., slope conditions), stand (e.g., tree volume) environmental (e.g., weather), and yard (e.g., winching distance) variables and to assess GHG emissions related to the equipment in use. This development was implemented in a timber harvesting practice under single-tree selection in mountainous forests of Iran where a motor-manual chainsaw is used for felling and a rubber-tired cable skidder is used for log extraction. The average delay-free productivity was 4.55 m3 for felling and 14.73 m3 h−1for skidding. Lower production costs and higher productivity rates were observed over the gentle slopes and in sunny conditions. The average production costs ranged between USD 4.27m−3 for felling and USD 5.35m−3 for skidding. The average emissions ranged between 0.96 kg m−3 for felling and 7.06 kg m−3 for skidding in snowy conditions over steep slopes. The study’s results confirm avoiding harvesting operations on steep slopes (greater than 35%) and in extreme weather conditions to obtain higher work efficiency and to minimize adverse effects of machinery on forest ecosystems. The results should be of use to harvest managers and forest planners considering the application of ground-based harvesting operations using a semi-mechanized system on a range of operating conditions in mountain hardwood stands.

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Norway Spruce Stem Parameters in Sites with Different Stand Densities in Lithuanian Hemiboreal Forest

Forests ◽

10.3390/f12020201 ◽

2021 ◽

Vol 12 (2) ◽

pp. 201

Author(s):

Lina Beniušienė ◽

Edmundas Petrauskas ◽

Marius Aleinikovas ◽

Iveta Varnagirytė-Kabašinskienė ◽

Ričardas Beniušis ◽

...

Keyword(s):

Norway Spruce ◽

Stand Density ◽

Tree Height ◽

Linear Regression Models ◽

Forest Zone ◽

Branch Diameter ◽

Stem Wood ◽

Diameter At Breast Height ◽

Breast Height ◽

Stem Quality

Background and Objectives: The study aimed to determine the changes of the main stem and branch parameters of Norway spruce (Picea abies (L.) H. Karst) trees under different stand densities. More specifically, the objective was to develop the models for the determination of branch diameter in 0–6 m log from root collar, taken as one of the parameters directly influencing the stem quality. The study continues a piece of research on stem and branch parameters’ responses to different stand density (SD) in the plantations of coniferous tree species in Lithuania. Materials and Methods: The following key parameters were measured in this study: total tree height, diameter at breast height, height to the lowest live branch, height to the lowest dead branch, and diameter of all branches in 0–6 m log. The linear regression models to predict branch diameter in 0–6 m log were developed based on stand density (SD), tree characteristics (tree diameter at breast height, DBH; and tree height, H) and other related stem and branch parameters. Results and Conclusions: Directly measured tree DBH, branch diameters and number of branches in 0–6 m log decreased significantly with the increasing SD. In the 0–6 m log, the branch diameter and the diameter of the thickest branch were identified as the main parameters related to stem quality. The best fitted models, developed including SD, tree DBH, branch diameter, and diameter of the thickest branch in 0–3 m log, can be proposed as a predictor for stem-wood quality for Norway spruce in hemiboreal forest zone.

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Biomass retention and carbon stocks in integrated vegetation bands: a case study of mixed-age brigalow-eucalypt woodland in southern Queensland, Australia

The Rangeland Journal ◽

10.1071/rj14023 ◽

2015 ◽

Vol 37 (3) ◽

pp. 261 ◽

Cited By ~ 4

Author(s):

Justin G. Ryan ◽

Christine T. Fyfe ◽

Clive A. McAlpine

Keyword(s):

Aboveground Biomass ◽

Production Systems ◽

Soil Protection ◽

Grazing Land ◽

Diameter At Breast Height ◽

Breast Height ◽

Large Trees ◽

Eucalypt Woodland ◽

Pasture Area ◽

The Impact

Regrowth of native woody vegetation has the potential to provide an economically valuable source of carbon storage and other ecosystem services. There is a lack of readily applicable examples of how regrowth of forests and woodlands can be integrated with existing grazing production systems and provide soil-protection and water-retention benefits. A system of integrated vegetation bands (IVB) was applied to patchy regrowth of acacia and eucalypt vegetation in a grazed landscape of southern Queensland, Australia. Across a 39.8-ha catchment with 3–5% slope, regrowth of scattered native vegetation (18.4 ha) was surveyed and diameter at breast height and height for all woody plants were recorded. The IVB (6.3 ha) were then marked out as 25-m-wide bands set 100 m apart and offset at ~2–3% gradient to the contour line, retaining the densest/largest regrowth where possible. The data on diameter at breast height and height were analysed using allometric equations to compare aboveground biomass in the original regrowth condition (‘Original’) to that retained in the installed IVB (‘IVB-Riparian’). Estimates of aboveground biomass were calculated for the Original and IVB-Riparian and compared with three other potential regrowth-vegetation management ‘treatments’ in a desktop-modelling study. The models were designated as: (1) ‘Original’; (2) ‘Broad’ (broad-scale cleared with only a few large trees along a creek retained)’; (3) ‘Big Trees’ (only large trees >40 cm diameter at breast height retained); (4) ‘Riparian-IVB (bands of vegetation); and (5) ‘Riparian-IVB-Big Trees’ (large trees together with ‘IVB-Riparian’). In the non-forested area of the catchment, ‘Riparian-IVB-Big Trees’ (301 t), ‘Big Trees’ (249 t) and ‘Riparian-IVB’ (200 t) had the highest aboveground biomass retained, whereas ‘Broad’ resulted in the most pasture area (~33 ha) followed by ‘Riparian-IVB’ (~26 ha). The ‘Riparian-IVB’ treatment had the highest tree density within the vegetation bands and more than half (53%) of the original woody biomass in regrowth was retained on just under a quarter (23%) of the land area minimising the impact on the area of pasture/grazing land. This subsequently resulted in the ‘Riparian-IVB’ treatment having the highest carbon offset value (A$605 ha–1). The results demonstrate that the retention of native regrowth vegetation in either IVB or as large paddock trees can retain a large amount of aboveground biomass, with IVB having greater returns per hectare.

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Species-Specific Allometric Equations for Predicting Belowground Root Biomass in Plantations: Case Study of Spotted Gums (Corymbia citriodora subspecies variegata) in Queensland

Forests ◽

10.3390/f12091210 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1210

Author(s):

Trinh Huynh ◽

Grahame Applegate ◽

Tom Lewis ◽

Anibal Nahuel A. Pachas ◽

Mark A. Hunt ◽

...

Keyword(s):

Root Biomass ◽

Carbon Sink ◽

Terrestrial Ecosystems ◽

Carbon Accumulation ◽

Percentage Error ◽

Data Set ◽

Diameter At Breast Height ◽

Breast Height ◽

Corymbia Citriodora ◽

The Impact

Spotted gum (Corymbia citriodora spp. variegata; CCV) has been widely planted, has a wide natural distribution, and is the most important commercially harvested hardwood species in Queensland, Australia. It has a great capacity to sequester carbon, thus reducing the impact of CO2 emissions on climate. Belowground root biomass (BGB) plays an important role as a carbon sink in terrestrial ecosystems. To explore the potential of biomass and carbon accumulation belowground, we developed and validated models for CCV plantations in Queensland. The roots of twenty-three individual trees (size range 11.8–42.0 cm diameter at breast height) from three sites were excavated to a 1-m depth and were weighed to obtain BGB. Weighted nonlinear regression models were most reliable for estimating BGB. To evaluate the candidate models, the data set was cross-validated with 70% of the data used for training and 30% of the data used for testing. The cross-validation process was repeated 23 times and the validation of the models were averaged over 23 iterations. The best model for predicting spotted gum BGB was based on a single parameter, with the diameter at breast height (D) as an independent variable. The best equation BGB = 0.02933 × D2.5805 had an adjusted R2 of 0.854 and a mean absolute percentage error of 0.090%. This equation was tested against published BGB equations; the findings from this are discussed. Our equation is recommended to allow improved estimates of BGB for this species.

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