Développement d'un modèle de type arbre appliqué à la croissance des peuplements feuillus irréguliers du sud de la Belgique

1996 ◽  
Vol 26 (10) ◽  
pp. 1838-1848 ◽  
Author(s):  
P. Lejeune
Keyword(s):  
Stand Structure ◽  
Basal Area ◽  
Tree Stand ◽  
Individual Tree ◽  
Growing Period ◽  
Site Characteristics ◽  
Individual Tree Growth ◽  
Forest Mensuration ◽  
Individual Trees ◽  
Changes Over Time

A model predicting circumference growth of individual trees has been developed for mixed irregular stands dominated by Fagussilvatica L. in southeastern Belgium. This model integrates simultaneously tree, stand, and growing site characteristics without considering distances between individual trees. It has a determination coefficient of 40.1% and a residual standard deviation of 0.45 cm/year. Forest mensuration variables considered in the model are circumference, tree social position represented by the total basal area of trees greater than the subject tree, stand basal area, and some index of stand structure corresponding to the ratio of the variance over the mean circumference. The site component is essentially expressed by the length of the growing period. The low accuracy obtained for individual tree growth is relative because the results are used mainly after individual trees have been distributed into size classes. We have been able to show that the introduction of crown description in the model can increase its accuracy. But this modification requires a submodel describing crown changes over time.

Wood density in Norway spruce: changes with thinning intensity and tree age

2005 ◽  
Vol 35 (7) ◽  
pp. 1767-1778 ◽  
Author(s):  
Tuula Jaakkola ◽  
Harri Mäkinen ◽  
Pekka Saranpää
Keyword(s):  
Norway Spruce ◽  
Wood Density ◽  
Basal Area ◽  
Tree Age ◽  
Individual Tree ◽  
Thinning Intensity ◽  
Individual Tree Growth ◽  
Spruce Stands ◽  
Individual Trees

The effect of thinning intensity on growth and wood density in Norway spruce (Picea abies (L.) Karst.) was investigated in two long-term thinning experiments in southeastern Finland. The stands were approaching maturity, and their development had already been studied for 30 years. The intensities of thinning were low, normal, and high (i.e., the stand basal area after the thinning was, on average, 40, 27, and 24 m2·ha–1, respectively, in Heinola, and 30, 28, and 17 m2·ha–1 in Punkaharju, respectively). Compared with the low thinning intensity, the normal and high thinning intensities increased the basal-area increment of individual trees by 52% and 68%, respectively. Normal and high thinning intensities resulted in a relatively small reduction (1%–4%) of mean ring density compared with low thinning intensity. The random variation in wood density between and within trees was large. About 27% of the total variation in wood density was related to variation between rings. Our results indicate that the prevailing thinning intensities in Norway spruce stands in Fennoscandia cause no marked changes in wood density. At least, the possible reduction in wood density is low compared with the increase in individual tree growth.

Stand structure and growing space efficiency following thinning in an even-aged Douglas-fir stand

1988 ◽  
Vol 18 (7) ◽  
pp. 859-866 ◽  
Author(s):  
K. L. O'Hara
Keyword(s):  
Stand Structure ◽  
Volume Growth ◽  
Basal Area ◽  
Stand Density ◽  
Douglas Fir ◽  
Stem Volume ◽  
Projection Area ◽  
Individual Tree ◽  
Space Efficiency ◽  
Individual Trees

The growth of individual trees from four thinning treatments in a 64-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand was analyzed to determine desirable residual stand structures after thinning. Dominant and codominant trees had the highest individual tree stem volume growth rates over the previous 5 years, and accounted for most stand volume growth in thinned and unthinned stands. Two measures of growing space, crown projection area and sapwood basal area (a surrogate for leaf area), were used to measure how efficiently individual trees used their growing space. Crown classes were useful in characterizing growing space efficiency (volume growth per unit of growing space) only in the unthinned treatment. In thinned treatments, tall trees with medium-sized crowns were most efficient, while in the unthinned treatment, tall trees with relatively large crowns were most efficient. A large crown in an unthinned stand was comparable in size to a medium-sized crown in a thinned stand. Results suggest growing space is not limiting individual tree growth in thinned stands and that thinning to a particular stand structure is more appropriate than thinning to a particular level of stand density.

scholarly journals Spruce Budworm Defoliation and Growth Loss in Young Balsam Fir: Estimation of Volume Growth Based on Stem Analysis and Increment Cores at Breast Height

1996 ◽  
Vol 13 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Harald Piene ◽  
Janine D'Amours ◽  
Alan A. Bray
Keyword(s):  
Volume Growth ◽  
Basal Area ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Stem Analysis ◽  
Individual Tree ◽  
Breast Height ◽  
Individual Tree Growth ◽  
Growth Loss ◽  
Changes Over Time

Abstract Comparisons of estimates of volume and volume increment, based on increment cores sampled at breast height and on stem analysis, were made in a young balsam fir stand that had been defoliated by spruce budworm. Use of increment cores is not recommended to estimate individual tree growth, because large errors, ranging from 20.9 to 57.2%, and error variability can be expected. The inability, when using increment cores, to estimate basal area is the major source of this variation. Although large uncertainties are associated with future growth predictions, on a per ha basis, changes over time based on increment cores may in some instances give comparable results to those based on stem analysis due to the canceling effect of trees being approximately equally overestimated and underestimated. However, a prerequisite is that the defoliation history and the year of individual tree death are known in detail to aid in the correct dating of ring widths. North. J. Appl. For. 13(2):73-78.

scholarly journals Adjudicating Perspectives on Forest Structure: How Do Airborne, Terrestrial, and Mobile Lidar-Derived Estimates Compare?

2021 ◽  
Vol 13 (12) ◽  
pp. 2297
Author(s):  
Jonathon J. Donager ◽  
Andrew J. Sánchez Meador ◽  
Ryan C. Blackburn
Keyword(s):  
Ponderosa Pine ◽  
Laser Scanning ◽  
Canopy Cover ◽  
Basal Area ◽  
Tree Height ◽  
Absolute Error ◽  
Forest Monitoring ◽  
Individual Tree ◽  
Structural Configurations ◽  
Individual Trees

Applications of lidar in ecosystem conservation and management continue to expand as technology has rapidly evolved. An accounting of relative accuracy and errors among lidar platforms within a range of forest types and structural configurations was needed. Within a ponderosa pine forest in northern Arizona, we compare vegetation attributes at the tree-, plot-, and stand-scales derived from three lidar platforms: fixed-wing airborne (ALS), fixed-location terrestrial (TLS), and hand-held mobile laser scanning (MLS). We present a methodology to segment individual trees from TLS and MLS datasets, incorporating eigen-value and density metrics to locate trees, then assigning point returns to trees using a graph-theory shortest-path approach. Overall, we found MLS consistently provided more accurate structural metrics at the tree- (e.g., mean absolute error for DBH in cm was 4.8, 5.0, and 9.1 for MLS, TLS and ALS, respectively) and plot-scale (e.g., R2 for field observed and lidar-derived basal area, m2 ha−1, was 0.986, 0.974, and 0.851 for MLS, TLS, and ALS, respectively) as compared to ALS and TLS. While TLS data produced estimates similar to MLS, attributes derived from TLS often underpredicted structural values due to occlusion. Additionally, ALS data provided accurate estimates of tree height for larger trees, yet consistently missed and underpredicted small trees (≤35 cm). MLS produced accurate estimates of canopy cover and landscape metrics up to 50 m from plot center. TLS tended to underpredict both canopy cover and patch metrics with constant bias due to occlusion. Taking full advantage of minimal occlusion effects, MLS data consistently provided the best individual tree and plot-based metrics, with ALS providing the best estimates for volume, biomass, and canopy cover. Overall, we found MLS data logistically simple, quickly acquirable, and accurate for small area inventories, assessments, and monitoring activities. We suggest further work exploring the active use of MLS for forest monitoring and inventory.

Fertilized Midrotation-Aged Slash Pine Plantations—Stand Structure and Yield Prediction Models

1989 ◽  
Vol 13 (2) ◽  
pp. 76-80 ◽  
Author(s):  
Robert L. Bailey ◽  
Thomas M. Burgan ◽  
Eric J. Jokela
Keyword(s):  
Prediction Models ◽  
Stand Structure ◽  
Basal Area ◽  
Slash Pine ◽  
Pine Plantations ◽  
Individual Tree ◽  
Investment Opportunities ◽  
User Friendly ◽  
Volume Equations ◽  
Soil Groups

Abstract Data from 263 plots in a regional fertilization study of midrotation-aged slash pine plantations were used to fit prediction equations for basal area, trees per acre, stand average dominant height, diameter distributions, and individual tree heights. The equations include N and P fertilizationrates and CRIFF soil groups as predictor variables. The survival model also accounts for the accelerating effect of fusiform rust on mortality rate. Using published tree volume equations, the prediction of volumes by dbh class for fertilized slash pine plantations is now possible. This integratedsystem of equations is available as a user-friendly computer program that can calculate expected yields by diameter class and aid the forester in evaluating investment opportunities that include forest fertilization. South. J. Appl. For. 13(2):76-80.

Growth response to thinning and its relation to site resources in Eucalyptusregnans

1995 ◽  
Vol 25 (1) ◽  
pp. 69-80 ◽  
Author(s):  
P.W. West ◽  
G.H.R. Osier
Keyword(s):  
Biomass Production ◽  
Tree Growth ◽  
Aboveground Biomass ◽  
Growth Response ◽  
Radiation Absorption ◽  
Light Use Efficiency ◽  
Individual Tree ◽  
Individual Tree Growth ◽  
Use Efficiency ◽  
Individual Trees

The factors determining individual tree growth response are examined during the 4 years following thinning in experiments in even-aged, 8- or 12-year-old regrowth Eucalyptusregnans F. Muell. forest at two sites in southern Australia. At one site, a vigorous understorey dominated by a sedge developed after the thinning. At that site, light-use efficiency by the trees was unaffected by thinning and the aboveground biomass production by the trees in the thinned stand was substantially less than that in the unthinned stand. At the other site, little understorey developed, light-use efficiency by trees in the thinned stand was greater than that in the unthinned stand, and aboveground biomass production was unaffected by thinning even though the leaf weight of the thinned stand was far below that of the unthinned stand. Where the understorey developed, it was concluded that it competed successfully with the trees for water, thereby reducing production in the thinned stand when compared with the unthinned stand. The individual tree growth response that occurred in the thinned stand at that site appeared to be due soley to the extra light available to individual trees following the canopy opening. Where the understorey did not develop, it was concluded that individual tree growth response was due not only to the extra light available to individual trees but also to the increased availability of belowground resources, most probably soil water. Application of a pre-existing stand growth model suggested that at that site the tendency for increased growth resulting from extra water availability in the thinned stand was just balanced by decreased growth due to lower radiation absorption by the reduced canopy, so that net production was unaffected by thinning.

scholarly journals Virtual forest stand as a component of sophisticated forestry educational systems

2012 ◽  
Vol 49 (No. 9) ◽  
pp. 419-428 ◽  
Author(s):  
M. Fabrika
Keyword(s):  
Stand Structure ◽  
Forest Stand ◽  
Geographical Information ◽  
Educational Systems ◽  
Individual Tree ◽  
E Learning ◽  
Forest Mensuration ◽  
Internet Environment ◽  
Growth Simulator ◽  
Virtual Reality Model

The paper presents the methodology of virtual stand generation. Virtual stand serves for forestry e-learning as a tool for training of forest tending and demonstration of stand structure and some forest mensuration practices. The model can be connected with growth simulator and geographical information system, or integrated into the Internet environment. In the first part of the paper, the methodology of individual tree visualisation, total stand visualisation, terrain and stand environment visualisation and the principle of user’s interaction with virtual forest are proposed. The Virtual Reality Model Language (VRML 97) was used for these goals. In the second part of the paper, an example of model usage for the training of forest tending is presented.

Modelling growing space requirement for Alnus nepalensis D. Don in Nepal

1970 ◽  
Vol 16 (2) ◽  
pp. 30-36 ◽  
Author(s):  
Ram Prasad Sharma
Keyword(s):  
Prediction Models ◽  
Growth Models ◽  
Basal Area ◽  
Individual Tree ◽  
Area Density ◽  
Space Requirement ◽  
Space Model ◽  
Alnus Nepalensis ◽  
Crown Diameter ◽  
Individual Trees

Relationship between crown diameter and stem diameter of individual trees can be translated into mathematical model, and used to generate information of growing space requirement for individual trees and crown competition index for growth models. Nine different crown diameter prediction models were developed using inventory data of Alnus nepalensis trees from a part of Parbat and Syanja districts in Nepal. Among those developed, a non-linear three parameter-based model (W = β0 {1 – exp( - β1D)}β2) explained the greatest proportion of variations of crown diameter (R2adj = 0.78), and showed desirable behaviour of flexibility and robustness. An individual tree growing space model was then derived from crown model to generate important information of shocking limits and stand basal area density for monoculture plantation or natural stands of Alnus nepalensis. Because of its flexibility, crown model is seemed potentially useful for extrapolation purpose also. However, the model cannot be applied for buttressed, wolfed and malformed trees. Key words: Alnus nepalensis; crown model; growing space model; stocking limit; basal area density Banko Janakari Vol.16(2) 2006 pp.30-36

Modeling of aboveground tree stand-level biomass in Erukot Forest of Oban Division, Cross River National Park, Nigeria

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
S.E. Bassey ◽  
S. Ajayi
Keyword(s):  
Carbon Dioxide ◽  
Aboveground Biomass ◽  
National Park ◽  
Basal Area ◽  
Tree Stand ◽  
Diameter At Breast Height ◽  
Total Height ◽  
Breast Height ◽  
Dry Biomass ◽  
Individual Trees

This research estimated aboveground tree stand level Biomass in Erukot Forest of Oban Division, Cross River National Park. A total of 872 individual trees were identified and measured for diameter at breast height and total height (dbh ≥ 5cm). The 872 individual trees spread across 51 species belonging to 25 different tree families. Simple random sampling was used with sampling intensity of 0.3% to lay 15 nested plots (7m x 7m, 25m x 25m and 35m x 35m). Diameter at breast height, total height and specific density of each wood species were used to determine aboveground biomass for each tree. Conversion factors were applied to estimate stand level green and dry biomass, sequestered carbon and carbon dioxide (CO2) emission in the study area. Simple linear regression models were fitted into the stand level growth data for the forest (basal area and volume). The mean diameter at breast height and mean total height were 38.5cm and 18.5m respectively. Mean basal area of 39.8 m2 ha-1 was obtained with a mean volume of 177.3 m3 ha-1 . Average green biomass, dry biomass, carbon stock and carbon-dioxide emission of 521.8113 ton ha-1 , 341.5880 ton ha-1 , 183.196 ton ha-1 and 694.2067 ton ha-1 respectively were obtained in the study area. Stand level biomass model developed for the forest showed that common logarithm of volume per hectare is significantly related to common logarithm of stand biomass (R2 = 58%). The actual and predicted biomasses were not significantly different (Paired T-test at p ˂ 0.05). Estimated bias of 0.10% for the stand biomass model means that the developed model can be used to predict the aboveground biomass of the study area without any adjustment. The research has provided easy to use regression model for determining aboveground biomass at stand level. This is very useful for carbon trade and assessment of carbon-dioxide emissions through deforestation in the study area. The model is also a tool for assessing the wood productivity of the study area and for better management of the park. Keyword: Sequestered carbon, aboveground biomass, dry biomass, conversion factor

A new method for evaluating forest thinning: growth dominance in managed Pinus resinosa stands

2010 ◽  
Vol 40 (5) ◽  
pp. 843-849 ◽  
Author(s):  
John B. Bradford ◽  
Anthony W. D’Amato ◽  
Brian J. Palik ◽  
Shawn Fraver
Keyword(s):  
Tree Growth ◽  
Basal Area ◽  
Pinus Resinosa ◽  
Growth Patterns ◽  
Red Pine ◽  
New Method ◽  
Stand Age ◽  
Individual Tree ◽  
Individual Tree Growth

Growth dominance is a relatively new, simple, quantitative metric of within-stand individual tree growth patterns, and is defined as positive when larger trees in the stand display proportionally greater growth than smaller trees, and negative when smaller trees display proportionally greater growth than larger trees. We examined long-term silvicultural experiments in red pine ( Pinus resinosa Ait.) to characterize how stand age, thinning treatments (thinned from above, below, or both), and stocking levels (residual basal area) influence stand-level growth dominance through time. In stands thinned from below or from both above and below, growth dominance was not significantly different from zero at any age or stocking level. Growth dominance in stands thinned from above trended from negative at low stocking levels to positive at high stocking levels and was positive in young stands. Growth dominance in unthinned stands was positive and increased with age. These results suggest that growth dominance provides a useful tool for assessing the efficacy of thinning treatments designed to reduce competition between trees and promote high levels of productivity across a population, particularly among crop trees.

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