Modeling relative error in stem basal area estimates

1990 ◽  
Vol 20 (5) ◽  
pp. 496-502 ◽  
Author(s):  
T. G. Gregoire ◽  
S. M. Zedaker ◽  
N. S. Nicholas

The computed estimate of basal area was the focus of this investigation into the accuracy of tree diameter measurements. Diameter at breast height was measured on 101 trees, the breast height disc was removed from the stem, and each disc outline was then digitized to determine its actual area. Actual areas were compared with the basal areas computed with the field measurements of diameter by expressing the deviations as a proportion of the actual areas. These relative errors averaged 3.1% when basal area was computed with a taped diameter at breast height, and they averaged −2.5% when the mean of two calipered, perpendicular diameter at breast height measurements were used. Noncircularity accounted for about 2.6% of the bias, on average, in basal areas from taped diameters. Root mean square error of relative basal area errors ranged from 7.3 to 7.9% among these methods. The difference between basal areas computed with a taped diameter at breast height and with calipered diameter at breast height was computed and expressed as a proportion of the actual basal area. On average, a difference of 5% was observed. Interval estimates for these differences are presented.

2019 ◽  
Vol 11 (14) ◽  
pp. 1680 ◽  
Author(s):  
Bayat ◽  
Noi ◽  
Zare ◽  
Bui

This paper examines the possible ecological controls on the diameter increment of oriental beech (Fagus orientalis Lipsky) in a high altitude forest in northern Iran. The main objectives of the study are computer-generated abiotic surfaces and associated plot estimates of (i) growing-season-cumulated potential solar radiation, (ii) seasonal air temperature, (iii) topographic wetness index in representing soil water distribution, and (iv) wind velocity generated from the simulation of fluid-flow dynamics in complex terrain. Plot estimates of the tree growth are based on averaged plot measurements of diameter at breast height increment during a growing period of nine years (2003–2012). Biotic variables related to the tree diameter increment involve averaged 2003 tree diameter and basal area measured in individual forest plots. In the modelling data (144 plots), the assemblage of modelled and observed site variables explained 75% of the variance in plot-level diameter increment. In the validation data (32 plots), the degree of explained variance was 77%. Mean tree diameter at breast height showed the strongest correlation with diameter increment, explaining 32% of the variation between-plot, followed by the configuration of topography and re-distribution of surface water (19.5%) and plot basal area (16.9%). On average, localised estimates of solar radiation and wind velocity potentially contribute to about 20% of the control on plot-level mean increment in oriental beech of the area. The results of the genetic programming showed that controlling the stand basal area and tree size by thinning and/or selective harvesting can have a favourable impact on the future distribution of mean diameter in oriental beech.


1981 ◽  
Vol 11 (2) ◽  
pp. 299-305 ◽  
Author(s):  
Eric J. Jokela ◽  
Colleen Ann Shannon ◽  
Edwin H. White

Biomass and nutrient accumulation by tree components for 66-year-old mature paper birch is presented. Logarithmic regression equations are given relating aboveground tree component biomass and contents of N, P, K, Ca, and Mg to tree diameter at breast height (dbh). Branches, bole bark, and bole wood accounted for 90–97% of the total aboveground tree biomass. Highest concentrations of most nutrients were in the foliage. For the tree of mean basal area (dbh = 15 cm), the crown components of branches and foliage constituted only 16% of the biomass but accounted for 49, 57, 53, 37, and 44%, respectively, of the N, P, K, Ca, and Mg accumulated.


2017 ◽  
Vol 149 (4) ◽  
pp. 487-490
Author(s):  
Tyler D. Nelson ◽  
Jon D. Sweeney ◽  
Neil Kirk Hillier

AbstractTetropium fuscum (Fabricius) (Coleoptera: Cerambycidae) is an invasive phloeophagous beetle established in Atlantic Canada that infests stressed and moribund Picea Dietrich (Pinaceae) species. Successfully colonised trees tend to be large in diameter (>10 cm diameter at breast height), but whether diameter influences host selection, larval performance, or both, is unknown. We tested the hypothesis that T. fuscum host selection is influenced by visual cues associated with tree diameter by counting the number of adults landing on 29 Picea rubens Sargent ranging in diameter at breast height from 12.2 to 37.5 cm. All trees were wrapped with sticky bands and baited with aggregation pheromone and host volatiles to make them equally attractive with regard to olfactory cues. We found significant positive relationships between the mean number of T. fuscum per sticky band and tree diameter, and also between phloem thickness and tree diameter. We conclude that the positive association between host diameter and T. fuscum infestation is at least partially due to the positive influence of diameter on landing rate, and that this may benefit the beetle because larger diameter trees have more food for developing larvae. However, there was no effect of tree diameter on the mean number of adults per m2 of sticky band and thus no evidence that T. fuscum actively selects larger diameter hosts based on visual cues. The positive relationship between landing rate and host diameter may simply be due to greater chances of airborne beetles being passively intercepted on larger versus smaller trees.


1993 ◽  
Vol 15 (4) ◽  
pp. 1-6
Author(s):  
Di Paola Mario ◽  
Nguyen Dong Anh

Stochastic linearization method is one of the most useful tools for analysis of nonlinear systems under random excitation. The fundamental idea of the classical stochastic linearization consists in replacing the original nonlinear equation by a linear one in such a way that the difference between two equations is minimized in the mean square value. In this paper a new version of the stochastic linearization is proposed. It is shown that for two nonlinear systems considered the new version gives good results for both the weak and strong nonlinearities.


2018 ◽  
Vol 56 ◽  
pp. 130-135
Author(s):  
M. V. Tserenyuk ◽  
O. M. Tserenyuk

In addition to assessing the absolute performance of animals, the impact of certain technological approaches, breeding influence and other external organized factors on the consolidation of pigs groups on certain grounds should be evaluated. Breeding consolidation is a desirable breeding process that is realized through more motivated consolidation of intra-breeding structural units for maintaining a significant level of intergroup differentiation and variability. If the issue relates to the rearing young animals that are introduced into the herd, this is the most urgent issue that needs to be monitored. The purpose of the research is to determine the consociality of the main signs of reproductive ability of the gilts, which are checked at different rates of artificial insemination of sows of the main herd. The research was carried out at the Shubs`ke farm in the Bogoduhivsky District of Kharkiv Oblast at the pig farm for the pure breeding of the Welsh breed pigs (breeding reproductive status from 2014). In order to evaluate the optimal multiplicity (from single to triple), a gilts with a total of 30 heads was selected. The main indicators of reproductive ability of gilts (multiplicity, weight of nest at birth and excommunication and keeping piglets before weaning on day 28) were evaluated. Recalculation on the weight of the litter at weaning at the weight of the nest at extermination in 60 days was carried out in accordance with the current instruction on the boning of pigs. The results of researches were worked out according to traditional methods by the method of variation statistics. Consolidation of individual indicators of reproductive capacity of gilts was calculated to the total number of evaluated animals. In the previous stage of the research, it was found that the use of multiple insemination of gilts compared to single insemination is positively reflected at the level of their reproductive ability. A decrease in the percentage of non-productive inseminants in animal groups has been established. Triple insemination of gilts allows for 1.14 piglets to be obtained more compared to single insemination of the same pigs (p < 0.01). Also, for three times insemination of gilts, in comparison with single insemination, larger nest for weaning were obtained (by 14.24 kg, converted to 60th day p < 0.01). At the same time, the reduction in the keeping of piglets to weaning for increase frequency of insemination of gilts. According to the multiplicity of gilts, the most consolidated level of symptoms per group was obtained for single insemination. Increasing the multiplicity of insemination negatively affected the consolidation of the multiplicity of the piglets (as for determining the coefficients of phenotypic consolidation due to the mean square deviation, so, and for determining the coefficient of variability). The least consolidated in terms of multiplicity were uterus for double insemination. It should also be noted that there is little difference, in general, on the indicators of the theonotypical consolidation of the multiplicity of piglets between different groups of animals. So this difference between the most contrasting groups was 0.447 points for determining the coefficients due to the mean square deviation and 0.397 points for the determination due to the coefficient of variability, respectively. By weight of the same litters at birth, the most consolidated group was gilts, which was inseminated twice. The least consolidated are trimmed three times, respectively. The difference as a whole, according to the indicators of the theonotype consolidation of the mass of the litter’s piglets at birth, between different groups of pigs was even smaller. The difference between the most contrasting groups was 0.270 points for determining the coefficients due to the mean square deviation and 0.260 points for the determination due to the coefficient of variability, respectively. On the basis of the mass of the litter at weaning, the most consolidated level of symptoms was obtained in the group of gilts for triple insemination. The least consolidated group, respectively, was gilts for single insemination. At the same time, on the basis of the weight of the litter at weaning, the slightest differences were obtained after the consolidation of the signs between different groups of pigs. The difference between the most contrasting groups was 0.173 points for determining the coefficients due to the mean square deviation and 0.248 points for the determination due to the coefficient of variation, respectively. At different rates of insemination of gilts, there are no significant differences between the groups between the groups in terms of the consolidation of signs of reproductive ability. Also, there was no clear effect on increasing the multiplicity of insemination of gilts to the consolidation of their signs of reproductive qualities.


2019 ◽  
Vol 2019 (11) ◽  
Author(s):  
Haruki Kurasawa ◽  
Toshio Suzuki

Abstract The relativistic expression for the $n$th-order moment of the nuclear charge density is presented. For the mean square radius (msr) of the nuclear charge density, the non-relativistic expression, which is equivalent to the relativistic one, is also derived consistently up to $1/M^2$ with use of the Foldy–Wouthuysen transformation. The difference between the relativistic and non-relativistic expressions for the msr of the point proton density is also discussed. The $n(\ge 4)$th-order moment of the nuclear charge density depends on the point neutron density. The fourth-order moment yields useful information on the msr of the point neutron density, and is expected to play an important role in electron scattering off neutron-rich nuclei.


1976 ◽  
Vol 6 (4) ◽  
pp. 441-447 ◽  
Author(s):  
David A. MacLean ◽  
Ross W. Wein

Biomass accumulation in 12 jack pine and 11 mixed hardwood stands of fire origin ranging in age from 7 to 57 years is presented. Logarithmic equations relating aboveground tree, crown, and stem biomass to tree diameter at breast height are given for eight tree species.


2014 ◽  
Vol 48 (1) ◽  
Author(s):  
Łukasz Pawlik

AbstractThe main subject of this article is the tree uprooting process and its effects on forested hillslopes in the Sudety Mts. The research has been carried out between 2010 and 2012 in the Karkonosze National Park (KNP), Stołowe Mountains National Park (SMNP) and Suche Mts. The methods included: detailed geomorphological mapping and measurements of root plates of recently fallen trees and relict treethrow mounds and pits (called pit-and-mound microtopography), their qualitative description and measurements of diameter at breast height (dbh) of uprooted tree trunks.The mean root plate volume was 0.3-1.4 mIt has been shown that tree uprooting can contribute to the evolution of regolith and soils and it is an important factor of their disturbances. This reflects results from other sites in the World. However, in the Sudety Mts. the significance of tree uprooting has been validated only locally and it is suggested that its importance decreases proportionally to the area under consideration. Here, biogenic transport is limited to treethrow pits on gentle hillslopes but can be much more effective at steeper sites.


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