Comparing the Efficiency of Three Inventory Sampling Methods To Determine Timber Volumes in Pinyon-Juniper Woodlands

1992 ◽  
Vol 7 (4) ◽  
pp. 110-113 ◽  
Author(s):  
Bruce E. Fox ◽  
Pamela E. Raskob
Keyword(s):  
Standard Error ◽  
Sampling Methods ◽  
Field Measurements ◽  
Measurement Time ◽  
Point Sampling ◽  
Plot Sampling ◽  
Transect Sampling ◽  
The Mean ◽  
Time Required ◽  
Line Intercept

Abstract We compared three sampling methods to determine timber volumes in pinyon-juniper (Pinus edulis-Juniperus spp.) woodlands, fixed radius plots, variable radius "point" sampling, and line intercept transects. Based on the criterion of the square of the standard error of the mean volume per acre multiplied by total time required to take the field measurements, line intercept transect sampling was the most efficient method. Fixed plot sampling had the highest standard error of the mean and highest measurement time, while point sampling fell between the other two methods in measurement time and standard error of the mean. Based on this analysis, transect sampling is an efficient approach for inventorying pinyon-juniper woodlands, in terms of required field time and in the variance estimates of volume per acre. West. J. Appl. For. 7(4):110-113.

scholarly journals COMPARAÇÃO ENTRE OS MÉTODOS DE AMOSTRAGEM DE BITTERLICH E DE ÁREA FIXA COM PARCELA CIRCULAR EM PLANTAÇÃO DE Pinus taeda

FLORESTA ◽  
2010 ◽  
Vol 40 (4) ◽  
Author(s):  
João Paulo Druszcz ◽  
Nelson Yoshihiro Nakajima ◽  
Sylvio Péllico Netto ◽  
Mauro Yoshitani Júnior
Keyword(s):  
Pinus Taeda ◽  
Sampling Method ◽  
Sampling Methods ◽  
Basal Area ◽  
Plot Sampling ◽  
Fixed Area ◽  
Plot Area ◽  
The Mean ◽  
Pinus Taeda L

Este estudo objetivou comparar o método de amostragem de Bitterlich e o de área fixa com Parcela Circular. Estes dois métodos foram avaliados quanto à precisão e eficiência na estimativa das variáveis DAP médio, número de árvores, área basal e volume total, por hectare. Foram selecionadas três condições de plantios de Pinus taeda, localizados na fazenda Boa Vista, no município de Carambeí – PR. Na análise simultânea das três condições para as estimativas das variáveis DAP médio e número de árvores, por hectare, o método de amostragem de área fixa com Parcela Circular foi o mais preciso e eficiente. Já para a análise de área basal e volume total, por hectare, o método de amostragem de Bitterlich foi o mais preciso e eficiente. Conclui-se que o método de área fixa com Parcela Circular foi mais preciso e eficiente para a estimativa das variáveis DAP médio e número de árvores, já que se trata de um método no qual a seleção dos indivíduos é proporcional à área da parcela. O método de Bitterlich, por ser um método que faz a seleção dos indivíduos com probabilidade à área basal, foi mais preciso e eficiente para a estimativa das variáveis área basal e volume total.Palavras-chave: Método de amostragem; precisão e eficiência; Pinus taeda. AbstractComparison between Bitterlich and fixed area circular plot sampling methods in Pinus taeda L plantation. This study aimed to compare the Bitterlich sampling method to the fixed area circular plot. These two methods were evaluated with respect to the accuracy and efficiency for estimating the variables mean DBH, number of trees, basal area and total volume per hectare. Three conditions for Pinus taeda plantations were selected. They were located in Boa Vista farm, Carambeí County, State of Paraná. Results showed that the fixed area circular plot was more efficient and accurate to estimate the mean DBH and the number of trees per hectare because it is a method where the trees selection is proportional to the plot area, whereas the Bitterlich method was more efficient and accurate to estimate the basal area and the total volume per hectare because the trees selection is related to the basal area.Keywords: Sampling methods; accuracy and efficiency; Pinus taeda.

Comparison of forest age estimators using k-tree, fixed-radius, and variable-radius plot sampling

2018 ◽  
Vol 48 (8) ◽  
pp. 942-951
Author(s):  
Brent D. Burch ◽  
Andrew J. Sánchez Meador
Keyword(s):  
Spatial Pattern ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Sampling Methods ◽  
Tree Age ◽  
Variable Radius ◽  
Plot Sampling ◽  
Age Patterns ◽  
Fixed Radius ◽  
The Mean

Quantifying the age characteristics of a forest can provide valuable information about the forest’s impact on the environment. For instance, the age of a forest can affect the ecosystem’s carbon exchange, soil enzyme activity, and biodiversity. In this paper, we investigate the use of different sampling methods to estimate the age characteristics of three simulated ponderosa pine (Pinus ponderosa Dougl. ex P. Lawson & C. Lawson) forests having different spatial and age patterns. This includes estimating the mean tree age and the age-class distribution of the trees in the forest. The trees in the sample are selected using k-tree sampling, fixed-radius plot sampling, or variable-radius plot sampling, and we compare the properties of the resulting estimators via design-based and model-based approaches. Analyses of the different sampling methods applied to the three forests suggest that the estimator associated with k-tree sampling, with the addition of a few extra trees per plot, is feasible for forests having a spatially mosaic or random spatial pattern. The estimator associated with fixed-radius plot sampling performed well for the forest having a clustered spatial pattern.

scholarly journals Point-Transect Surveys for Songbirds: Robust Methodologies

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 345-357 ◽  
Author(s):  
Stephen T. Buckland
Keyword(s):  
Sampling Methods ◽  
Bird Species ◽  
Single Species ◽  
Line Transect ◽  
Line Transect Sampling ◽  
Point Sampling ◽  
Transect Sampling ◽  
Single Location ◽  
Point Transect ◽  
Generally True

Abstract Point-transect sampling is widely used for monitoring trends in abundance of songbirds. It is conceptualized as a “snapshot” method in which birds are “frozen” at a single location. With conventional methods, an observer records birds detected from a point for several minutes, during which birds may move around. This generates upward bias in the density estimate. I compared this conventional approach with two other approaches: in one, the observer records locations of detected birds at a snapshot moment; in the other, distances to detected cues (songbursts), rather than birds, are recorded. I implemented all three approaches, together with line-transect sampling and territory mapping in a survey of four bird species. The conventional method gave a biased estimate of density for one species. The snapshot method was found to be the most efficient of the point-sampling methods. Line-transect sampling proved more efficient than the point-sampling methods for all four species. This is likely to be generally true, provided that terrain and habitat allow easy use of a design with random transect lines. I concluded that the snapshot method is more appropriate than the conventional timed-count method for surveying songbirds. Although precision was rather poor with the cue-based method (partly because too few resources were devoted to cue rate estimation), it may be particularly useful for some single-species surveys. In addition, it is the only valid method for estimating abundance from surveys in which acoustic equipment is used to detect birds. Muestreos en Transectos Puntuales para Aves Canoras: Metodologías Robustas

Variability of Line Intercept Density Estimates (A Simulation Study of the Variance of Hydroacoustic Biomass Estimates)

1981 ◽  
Vol 38 (9) ◽  
pp. 1141-1152 ◽  
Author(s):  
Daniel K. Kimura ◽  
Norman A. Lemberg
Keyword(s):  
Variance Component ◽  
Density Estimates ◽  
Sampling Density ◽  
Relative Variance ◽  
Transect Sampling ◽  
The Mean ◽  
Patch Configuration ◽  
Parallel Sampling ◽  
Hydroacoustic Survey ◽  
Line Intercept

"Line intercept density estimates" are defined as estimates of mean density arrived at by sampling density along randomly selected transects. For these estimates, the school (or patch) configuration being sampled strongly influences the variance of the mean density estimate. By simulating schools as circles (or ellipsoids) the variance component due to schooling was calculated by numerical integration, where the variance generating probability measure was a uniform distribution determined by the type of transect sampling employed. Results indicate that the component of variability due to schooling is large; that it can be effectively reduced (at practical sampling levels) by increasing sampling density; and that relative variance (as measured by a coefficient of variation) is extremely sensitive to the percentage of the sampling region covered by schools. Stratified methods of sampling (zig–zag and stratified parallel) were uniformly more efficient than random parallel sampling. Furthermore, zig–zag sampling was more efficient than stratified parallel sampling at low sampling intensities, while the opposite was true at high sampling intensities. No difference in efficiency was detected between sampling a rectangular as opposed to a square region. Although analyses were aimed principally at evaluating the variability of hydroacoustic biomass estimates, results are also applicable to line intercept estimates common in field ecology.Key words: transect sampling, hydroacoustic survey, simulation

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

scholarly journals An alternative to the rejection of observations

1932 ◽  
Vol 137 (831) ◽  
pp. 78-87 ◽  
Keyword(s):  
Standard Deviation ◽  
Continuous Function ◽  
Large Deviations ◽  
Opposite Direction ◽  
Standard Error ◽  
The Other ◽  
Cause Of Error ◽  
The Mean ◽  
Normal Law ◽  
Usual Rule

1. It is widely felt that any method of rejecting observations with large deviations from the mean is open to some suspicion. Suppose that by some criterion, such as Peirce’s and Chauvenet’s, we decide to reject observations with deviations greater than 4 σ, where σ is the standard error, computed from the standard deviation by the usual rule; then we reject an observation deviating by 4·5 σ, and thereby alter the mean by about 4·5 σ/ n , where n is the number of observations, and at the same time we reduce the computed standard error. This may lead to the rejection of another observation deviating from the original mean by less than 4 σ, and if the process is repeated the mean may be shifted so much as to lead to doubt as to whether it is really sufficiently representative of the observations. In many cases, where we suspect that some abnormal cause has affected a fraction of the observations, there is a legitimate doubt as to whether it has affected a particular observation. Suppose that we have 50 observations. Then there is an even chance, according to the normal law, of a deviation exceeding 2·33 σ. But a deviation of 3 σ or more is not impossible, and if we make a mistake in rejecting it the mean of the remainder is not the most probable value. On the other hand, an observation deviating by only 2 σ may be affected by an abnormal cause of error, and then we should err in retaining it, even though no existing rule will instruct us to reject such an observation. It seems clear that the probability that a given observation has been affected by an abnormal cause of error is a continuous function of the deviation; it is never certain or impossible that it has been so affected, and a process that completely rejects certain observations, while retaining with full weight others with comparable deviations, possibly in the opposite direction, is unsatisfactory in principle.

Seasonal Changes in the Water Relations of Eucalyptus behriana F. Muell. And E. microcarpa (Maiden) Maiden in the Field

1984 ◽  
Vol 32 (5) ◽  
pp. 495 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Rainfall Intensity ◽  
Field Measurements ◽  
Canopy Conductance ◽  
Laboratory Studies ◽  
Short Term ◽  
The Mean ◽  
Type Response ◽  
Vapour Pressure Difference

Field observations of some parameters of the water relations of the two eucalypt species E. behriana and E. microcarpa in dry sclerophyll, mallee and woodland vegetation were made at three sites from 1980 to 1983. The mean ( n = 519) water potential measured at dawn (Ψdawn) was -3.07± 0.01 MPa and fluctuated seasonally with rainfall intensity over the range -2.0 ± 0, 1 to -4.4 ± 0.1 MPa ( n = 30). Both species behaved similarly and some osmotic adjustment took place. Mean leaf conductance (gs) varied between 0.151 ± 0.006 and 0.003 ± 0.001 mol m-2 s-1 . Maximum daily values of gs were linearly related to Ψdawn as it fluctuated seasonally. The slope of this linear regression was not significantly different from that relating these values of gs and Ψ, when both were measured concurrently. There were thus no indications of a distinction between the responses of gs to long- and short-term fluctuations of Ψ or of a threshold-type response of gs to Ψ. Field measurements indicated that gs was decreased at high values of vapour pressure difference (Δe). In laboratory studies with seedlings of the two species gs decreased from 0.5 to 0.1 mol m-2 s-I as Δe increased from 0.5 to 3.0 kPa. Leaf and canopy conductance were the predominant plant determinants of transpiration rate (Er) in this type of vegetation which has the capacity to restrict Et via the effect of water potential (Ψ) on gs and also by the response of gs to Δe. Some of the water relations parameters of E. behriana indicated that this species was better able to withstand drought than was E microcarpa.

scholarly journals Comparison of Fissure Sealant Chair Time and Patients’ Preference Using Three Different Isolation Techniques

Children ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 444
Author(s):  
Rahif E. Mattar ◽  
Ayman M. Sulimany ◽  
Saad S. Binsaleh ◽  
Ibrahim M. Al-Majed
Keyword(s):  
Fissure Sealant ◽  
King Saud University ◽  
Rubber Dam ◽  
Dental Clinics ◽  
Isolation Techniques ◽  
Permanent Molars ◽  
Pit And Fissure Sealant ◽  
The Mean ◽  
Time Required ◽  
Cotton Roll

This randomized clinical trial aimed to evaluate the patient’s preference and chair time needed during pit and fissure sealant placement under three isolation techniques (Isolite system, rubber dam isolation, and cotton roll isolation). Participants, aged 6–15 years and requiring four sealants on the first or second permanent molars, attending the pediatric dental clinics at King Saud University in Saudi Arabia were enrolled according to the inclusion criteria. Each participant received sealants on three random first or second permanent molars using three isolation techniques. The time required for sealant placement was recorded for each technique. Following sealant placement, an interview-based questionnaire was administered to the participants to evaluate their preference regarding the isolation techniques. Forty-eight children (23 male and 25 female) with a mean age of 8.58 ± 1.93 years participated in this study. The mean chair times were 248.14, 255.89, and 243.29 s for the Isolite system, rubber dam isolation, and cotton roll isolation, respectively. Approximately 79% of participants considered cotton roll isolation to be the most comfortable, whereas approximately 71% were significantly less likely to use rubber dam isolation again. In conclusion, there were no significant differences in sealant placement time among the three isolation techniques. However, cotton roll isolation was the technique that was most preferred by the participants.

scholarly journals Time required to move cash through slot machines

2018 ◽  
Vol 21 (3) ◽  
pp. 376-384 ◽  
Author(s):  
Karen Kelly ◽  
Carl James Schwarz ◽  
Ricardo Gomez ◽  
Kim Marsh
Keyword(s):  
British Columbia ◽  
Slot Machines ◽  
Content Type ◽  
The Public ◽  
Average Value ◽  
The Mean ◽  
Time Required ◽  
Rest Breaks ◽  
Mean Time ◽  
Practical Implications

Purpose The purpose of this paper is to present an empirical study on the time needed to load and disburse cash using bill validators on slot machines and stand-alone cash dispensers in casinos in British Columbia under a Ticket In Ticket Out (TITO) system. Design/methodology/approach Testing took place over two days, using 18 machines. The results were extrapolated to estimate the approximate time required to process $1,000,000 with different average bill amounts in the cash mix and three different bill validator machines in common use. The average value per bill using the cash mix used by the public in the casino was $33.11 [standard error (SE) $2.11]. Findings The mean time/accepted note ranged from 4.12 to 9.65 s, depending on bill validator type. This implies that the time needed to load $1,000,000 onto credit slips using bill validators on slot machines ranges from 35 to 81 h, excluding rest breaks and other breaks. The time needed to redeem $1,000,000 is estimated to be 3 h. Practical/implications The implications of these finding for illicit actors to successfully launder large amounts of cash are discussed. Given the time needed to physically handle the cash, and other control systems currently in use in casinos in British Columbia, processing large amounts of cash using bill validators on slot machines would require a highly organized team that would find it difficult to elude detection. Originality/value The trial results provide a baseline estimate to be used going forward when investigating or proposing money laundering methodologies that include slot machines.

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