scholarly journals A Comparison of Existing Models for DBH Estimation from Large-scale Photos

1989 ◽  
Vol 65 (2) ◽  
pp. 114-120 ◽  
Author(s):  
R. J. Hall ◽  
R. T. Morton ◽  
R. N. Nesby
Keyword(s):  
Large Scale ◽  
Prediction Models ◽  
Lodgepole Pine ◽  
Tree Height ◽  
White Spruce ◽  
Trembling Aspen ◽  
Crown Area ◽  
Balsam Poplar ◽  
Operational Test ◽  
Highly Correlated

The performance of 12 diameter prediction models suggested in the literature was studied in a controlled operational test. These models were linear and logarithmic transformations of tree height and/or crown area and were analyzed for white spruce, lodgepole pine, and trembling aspen and balsam poplar combined. Overall, all models were statistically significant, with differences due to variations in species and model form. Although simpler models may be adequate depending on operational objectives, two models emerged as deserving further investigation. It was unclear whether both tree height and crown area were needed as predictors of tree dbh for all species. Tree height was more highly correlated with dbh than crown area for all species except lodgepole pine. Measuring both tree height and crown area in comparison with tree height alone, however, increases measurement cost substantially from $10.29 to $17.50 per plot (1987 dollars).

Within-tree patterns of wood stiffness for white spruce (Picea glauca) and trembling aspen (Populus tremuloides)

2014 ◽  
Vol 44 (2) ◽  
pp. 162-171 ◽  
Author(s):  
Derek F. Sattler ◽  
Philip G. Comeau ◽  
Alexis Achim
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Radial Growth ◽  
Tree Height ◽  
White Spruce ◽  
Vertical Position ◽  
Trembling Aspen ◽  
Mixed Effect ◽  
Cambial Age ◽  
Rate Of Increase

Radial patterns of modulus of elasticity (MOE) were examined for white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuoides Michx.) from 19 mature, uneven-aged stands in the boreal mixedwood region of northern Alberta, Canada. The main objectives were to (1) evaluate the relationship between pith-to-bark changes in MOE and cambial age or distance from pith; (2) develop species-specific models to predict pith-to-bark changes in MOE; and (3) to test the influences of radial growth, relative vertical height, and tree slenderness (tree height/DBH) on MOE. For both species, cambial age was selected as the best explanatory variable with which to build pith-to-bark models of MOE. For white spruce and trembling aspen, the final nonlinear mixed-effect models indicated that an augmented rate of increase in MOE occurred with increasing vertical position within the tree. For white spruce trees, radial growth and slenderness were found to positively influence maximum estimated MOE. For trembling aspen, there was no apparent effect of vertical position or radial growth on maximum MOE. The results shed light on potential drivers of radial patterns of MOE and will be useful in guiding silvicultural prescriptions.

Estimating ovendry mass of trembling aspen and white birch using measurements from aerial photographs

1986 ◽  
Vol 16 (1) ◽  
pp. 163-165 ◽  
Author(s):  
I. S. Alemdag
Keyword(s):  
Pilot Study ◽  
Large Scale ◽  
Tree Height ◽  
Aerial Photographs ◽  
Tree Biomass ◽  
White Birch ◽  
Crown Area ◽  
Preliminary Results ◽  
Total Tree ◽  
Whole Tree

A pilot study tested the estimation of stem, crown, and whole-tree biomass of single trees from measurements of total tree height and crown area taken from large-scale aerial photographs. The results indicated the feasibility of this method, provided that time of photography is optimal. More extensive testing is required to confirm these encouraging preliminary results.

The interactive effect of competition and climate on growth of boreal tree species in western Canada and Alaska

2020 ◽  
Vol 50 (5) ◽  
pp. 457-464 ◽  
Author(s):  
Felix O. Oboite ◽  
Philip G. Comeau
Keyword(s):  
Interspecific Competition ◽  
Tree Growth ◽  
Intraspecific Competition ◽  
Tree Species ◽  
Basal Area ◽  
White Spruce ◽  
Jack Pine ◽  
Western Canada ◽  
Trembling Aspen ◽  
Balsam Poplar

Understanding interactions between competition and climate in relation to their effects on individual tree growth is crucial to the development of climate-sensitive growth models required for modelling boreal forest succession in a changing climate. We used data from permanent growth and yield sample plots in western Canada and Alaska to investigate the impact of competition within a regional gradient of climatic conditions for lodgepole pine (Pinus contorta Douglas ex Loudon), jack pine (Pinus banksiana Lamb.), trembling aspen (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.). We characterized the effects of competition (basal area of spruce–fir, deciduous, and pine trees larger than the focal tree) and climate (mean annual temperature and precipitation) and their interactions on basal area growth of individual trees using linear mixed-effects models. Our results indicated that intraspecific competition had stronger effects on growth than interspecific competition and climate. Moreover, significant interactions between intraspecific competition and climate suggest that an increase in intraspecific competition will lead to a reduction in tree growth for warmer regions (lodgepole pine, trembling aspen, balsam poplar, and white spruce) and wetter regions (jack pine). The manner in which interspecific competition altered tree growth responses to climate was variable, depending on tree species and competition type. These results indicate that the relationships between growth and climate may differ according to the degree of competition and the structure of the stand.

scholarly journals Stand-level Attributes of Snowshoe Hare (Lepus americanus) Habitat in a Post-Fire Trembling Aspen (Populus tremuloides) Chronosequence in Central Yukon

2013 ◽  
Vol 126 (4) ◽  
pp. 295 ◽  
Author(s):  
Wayne L. Strong ◽  
Thomas S. Jung
Keyword(s):  
Boreal Forest ◽  
Populus Tremuloides ◽  
Large Scale ◽  
Global Climate ◽  
Canopy Cover ◽  
White Spruce ◽  
Lepus Americanus ◽  
Snowshoe Hare ◽  
Trembling Aspen ◽  
Understory Shrubs

Large-scale fires are anticipated to increase in frequency in the boreal forest under global climate warming scenarios. To understand concomitant responses by wildlife to fire-induced habitat changes, fecal pellet counts were used to assess Snowshoe Hare (Lepus americanus) use of four age-classes of boreal forest after fire in central Yukon, Canada. Use of stands across a chronosequence of 8–177 years was bimodal. Post-fire Trembling Aspen (Populus tremuloides) stands ≤20 years old had greater densities of Snowshoe Hare pellets (median 156 pellets/dam2) than Trembling Aspen stands 21–70 years old, mixedwood stands 71–120 years old (<17 pellets/dam2), or Western White Spruce (Picea albertiana) -dominated stands 121–170 years old (71 pellets/dam2). Forty stand-level compositional and structural variables were assessed as possible predictors of Snowshoe Hare pellet densities. Multidimensional scaling was used to identify variables (n = 10) that were most strongly related to pellet densities and was followed by multiple regression. Canopy cover of Trembling Aspen <50 cm tall and Western White Spruce ≤1 m tall, and deadfall depth, in combination, were the best estimators of Snowshoe Hare pellet densities among stands in the chronosequence (P <0.001, 64.5% variance explained). Although Trembling Aspen <50 cm tall explained the most variance, its canopy cover did not exceed 10%. More Trembling Aspen cover <50 cm tall and greater deadfall depths within the chronosequence were associated with stands ≤20 years old. Peak Snowshoe Hare use occurred in early (≤20 years old) rather than mid-successional (21–120 years old) stands, contrary to use patterns reported elsewhere. The lack of tall understory shrubs likely limited the use of mid-successional stands.

Compatible diameter and height increment models for lodgepole pine, trembling aspen, and white spruce

2009 ◽  
Vol 39 (1) ◽  
pp. 180-192 ◽  
Author(s):  
Thompson K. Nunifu
Keyword(s):  
Populus Tremuloides ◽  
Lodgepole Pine ◽  
Volume Growth ◽  
White Spruce ◽  
Height Growth ◽  
Stem Density ◽  
Average Height ◽  
Height Increment ◽  
Trembling Aspen ◽  
Diameter Increment

In this study, compatible height and diameter increment models were fitted for lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.), trembling aspen ( Populus tremuloides Michx.), and white spruce ( Picea glauca (Moench) Voss), using the relationship between diameter and height growth. It was assumed that tree diameter increment is directly proportional to height increment, and the proportionality constant is a function of competition and site productivity. The results showed that the fit statistics are comparable with results of other studies, with adjusted R2 ranging from 30% to 50%. A validation test of the models, using independent permanent sample plots data, showed that the short-term predictions of the models for both pure and mixedwood stands are fairly unbiased. The models also gave reasonable average height growth and diameter growth trajectories for pure stands of the three species and also projected long-term mixedwood (aspen – white spruce mixture) volume growth dynamics reasonably well. The models also projected reasonably well (i) the effect of increasing initial stem density on average diameter and height, and (ii) the stand volume compared with an older version the Mixedwood Growth Model (ver. 2000A). It was concluded that explicitly linking tree height and diameter increment models does not only have a solid ecological basis, but it also results in a compatible prediction of tree growth and stand dynamics.

Estimating Weights of Tree Components of Lodgepole Pine from Large-Scale Aerial Photographs

1971 ◽  
Vol 1 (3) ◽  
pp. 193-194
Author(s):  
A. D. Kiil
Keyword(s):  
Large Scale ◽  
Lodgepole Pine ◽  
Tree Height ◽  
Aerial Photographs ◽  
Precise Estimate ◽  
Independent Variables ◽  
Crown Width ◽  
Air Photo ◽  
Total Tree ◽  
Fuel Components

Sixty-three lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) trees were measured on the ground, felled, and their crowns and stems were weighed. The combined independent variables of tree height and crown width gave the most precise estimate of fuel components. No significant differences were found between ground and air photo measurements of total tree height and crown width. Hence, the weight of all branchwood, entire crown, and entire tree can be estimated by the use of large-scale aerial photographs.

Lodgepole pine and white spruce crown fuel weights predicted from height and crown width

1989 ◽  
Vol 19 (4) ◽  
pp. 527-530 ◽  
Author(s):  
Allen F. Johnson ◽  
Paul M. Woodard ◽  
Stephen J. Titus
Keyword(s):  
Lodgepole Pine ◽  
Tree Height ◽  
White Spruce ◽  
Aerial Photographs ◽  
Allometric Model ◽  
Crown Width ◽  
Undisturbed Forest ◽  
Independent Variable ◽  
Total Tree ◽  
Diameter Classes

Equations were developed to predict the ovendry weight of the total crown, live crown, foliage, and the roundwood diameter classes of <0.5, 0.5–1.0, 1.0–3.0, 3.0–5.0, 5.0–7.0, 7.0–10.0 cm for lodgepole pine (n = 27) and white spruce (n = 23) occurring in Alberta, Canada. The nonlinear allometric model using total tree height and a measure of crown width provided high R2 and low SEE values. This precision could not be duplicated when total tree height was used as the only independent variable. Our results suggest the possibility of using tree height and crown width measured from aerial photographs to estimate standing live and dead fuel loadings in undisturbed forest stands.

Konkurrenz zwischen Stieleiche und Buche auf Lothar-Sturmflächen | Competition between pedunculate oak and European beech on Lothar windthrow areas

2009 ◽  
Vol 160 (5) ◽  
pp. 114-123 ◽  
Author(s):  
Daniel Otto ◽  
Sven Wagner ◽  
Peter Brang
Keyword(s):  
Large Scale ◽  
Early Stage ◽  
Tree Height ◽  
European Beech ◽  
Threshold Value ◽  
Test Methods ◽  
Permanent Plots ◽  
Pedunculate Oak ◽  
Competitive Pressure ◽  
Competition Index

The competitive pressure of naturally regenerated European beech (Fagus sylvatica) saplings on planted pedunculate oak (Quercus robur) was investigated on two 1.8 ha permanent plots near Habsburg and Murten (Switzerland). The plots were established with the aim to test methods of artificial oak regeneration after large-scale windthrow. On both plots, 80 oaks exposed to varying levels of competitive pressure from at most 10 neighbouring beech trees were selected. The height of each oak as well as stem and branch diameters were measured. The competitive pressure was assessed using Schütz's competition index, which is based on relative tree height, crown overlap and distance from competing neighbours. Oak trees growing without or with only slight competition from beech were equally tall, while oaks exposed to moderate to strong competition were smaller. A threshold value for the competition index was found above which oak height decreased strongly. The stem and branch diameters of the oaks started to decrease even if the competition from beech was slight, and decreased much further with more competition. The oak stems started to become more slender even with only slight competition from beech. On the moderately acid beech sites studied here, beech grow taller faster than oak. Thus where beech is competing with oak and the aim is to maintain the oak, competitive pressure on the oak must be reduced at an early stage. The degree of the intervention should, however, take the individual competitive interaction into account, with more intervention if the competition is strong.

Bioactivity Prediction Based on Matched Molecular Pair and Matched Molecular Series Methods

2020 ◽  
Vol 26 (33) ◽  
pp. 4195-4205
Author(s):  
Xiaoyu Ding ◽  
Chen Cui ◽  
Dingyan Wang ◽  
Jihui Zhao ◽  
Mingyue Zheng ◽  
...  
Keyword(s):  
Prediction Model ◽  
Large Scale ◽  
Prediction Models ◽  
Predictive Accuracy ◽  
Lead Optimization ◽  
Consensus Method ◽  
Molecular Pair ◽  
Bioactivity Prediction ◽  
Compound Synthesis ◽  
Consensus Modeling

Background: Enhancing a compound’s biological activity is the central task for lead optimization in small molecules drug discovery. However, it is laborious to perform many iterative rounds of compound synthesis and bioactivity tests. To address the issue, it is highly demanding to develop high quality in silico bioactivity prediction approaches, to prioritize such more active compound derivatives and reduce the trial-and-error process. Methods: Two kinds of bioactivity prediction models based on a large-scale structure-activity relationship (SAR) database were constructed. The first one is based on the similarity of substituents and realized by matched molecular pair analysis, including SA, SA_BR, SR, and SR_BR. The second one is based on SAR transferability and realized by matched molecular series analysis, including Single MMS pair, Full MMS series, and Multi single MMS pairs. Moreover, we also defined the application domain of models by using the distance-based threshold. Results: Among seven individual models, Multi single MMS pairs bioactivity prediction model showed the best performance (R2 = 0.828, MAE = 0.406, RMSE = 0.591), and the baseline model (SA) produced the most lower prediction accuracy (R2 = 0.798, MAE = 0.446, RMSE = 0.637). The predictive accuracy could further be improved by consensus modeling (R2 = 0.842, MAE = 0.397 and RMSE = 0.563). Conclusion: An accurate prediction model for bioactivity was built with a consensus method, which was superior to all individual models. Our model should be a valuable tool for lead optimization.

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