On critical-height sampling

1986 ◽  
Vol 16 (6) ◽  
pp. 1310-1313 ◽  
Author(s):  
Paul C. Van Deusen ◽  
Walter J. Meerschaert
Keyword(s):  
Spatial Patterns ◽  
Critical Height ◽  
Breast Height ◽  
Unbiased Estimates ◽  
Volume Equation ◽  
Volume Estimates ◽  
The Relationship ◽  
Tree Spatial Patterns

Critical-height sampling is shown to provide unbiased estimates of per-acre cubic volume if the sample trees are selected at stump height to determine if they are to be tallied. Selection at breast height implicitly assumes that the tree is a cylinder from breast height to stump height. It is also shown that unbiased estimates of merchantable volume can be obtained with critical-height sampling. The relationship between variances from critical-height sampling and the usual horizontal point procedure requiring volume estimates is shown to depend on tree spatial patterns. This is also true for growth estimates. A definite benefit of critical-height sampling is that no volume equation is needed.

Application of a geometrical volume equation to species with different bole forms

1986 ◽  
Vol 16 (2) ◽  
pp. 311-314 ◽  
Author(s):  
G. B. MacDonald ◽  
R. R. Forslund
Keyword(s):  
Diameter Measurement ◽  
Stem Analysis ◽  
Individual Tree ◽  
Breast Height ◽  
Centre Of Gravity ◽  
Variable Equation ◽  
Input Variables ◽  
Volume Equation ◽  
Volume Estimates ◽  
Geometrical Equation

Stem analysis of 20 Abiesbalsamea (L.) Mill., 68 Piceamariana (Mill.) B.S.P., 19 Piceaglauca (Moench) Voss, 31 Populustremuloides Michx., and 37 Betulapapyrifera Marsh. revealed form variation between species. A volume equation based on the paracone (a geometrical solid midway between a paraboloid and a cone) estimated individual tree volume within 10% of the true volume (at the 95% confidence level) for all species. The input variables required were total height and diameter at a relative height of 0.2 for Betulapapyrifera and 0.3 for the other four species. If breast-height diameter was used, the effect of form variation on the accuracy of volume prediction was more pronounced. In this case, the geometrical equation modified for each species according to the average centre of gravity provided more consistently accurate volume estimates than either the paracone equation or Honer's transformed variable equation. For all species, the diameter measurement position was more critical than the version of the geometrical equation selected.

scholarly journals Competition in Abies kawakamii forests at subtropical high mountain in Taiwan

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254791
Author(s):  
Wei Wang ◽  
Min-Chun Liao ◽  
Hsy-Yu Tzeng
Keyword(s):  
Plant Species ◽  
Spatial Patterns ◽  
Subtropical High ◽  
High Mountain ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Dominant Component ◽  
Understory Composition ◽  
The Relationship ◽  
Competition Indices

The spatial patterns of plant species reflect the competitive pressures on individuals. To generate Competition indices (CI), we measured the diameter at breast height (DBH), crown volumes (CV) and the distances between trees. In this study, Abies kawakamii were divided based on the dominant component of the understory (moss or bamboo) to (1) investigate the relationship between the CI and stand structural attributes (SSAs); (2) compare the inter- and intraspecies; CIs as well as living and dead individual CIs; and (3) examine the relationship between the DBH and CI. The current findings indicate that the understory composition affected the CI and SSAs. The interspecies CI was larger than the intraspecies CI when bamboo-dominated the understory. In contrast, the intraspecies CI was larger than the interspecies CI when the understory was dominated by moss. The CI of dead individuals was higher than that of live individuals due to the biological characteristics and regeneration needs of Abies. Additionally, sensitivity to the environment and available resources may exert more pressure on young individuals than mature individuals.

Variance reduction in Ueno's method and cylinder sampling for forest volume estimation

1995 ◽  
Vol 25 (11) ◽  
pp. 1783-1794 ◽  
Author(s):  
Thomas B. Lynch
Keyword(s):  
Computer Simulation ◽  
Variance Reduction ◽  
Volume Estimation ◽  
Critical Height ◽  
Volume Estimate ◽  
Individual Tree ◽  
Stand Volume ◽  
Reduction Techniques ◽  
Antithetic Variates ◽  
Volume Equation

Three basic techniques are proposed for reducing the variance of the stand volume estimate provided by cylinder sampling and Ueno's method. Ueno's method is based on critical height sampling but does not require measurement of critical heights. Instead, a count of trees whose critical heights are less than randomly generated heights is used to estimate stand volume. Cylinder sampling selects sample trees for which randomly generated heights fall within cylinders formed by tree heights and point sampling plot sizes. The methods proposed here for variance reduction in cylinder sampling and Ueno's method are antithetic variates, importance sampling, and control variates. Cylinder sampling without variance reduction was the most efficient of 12 methods compared in computer simulation that used estimated measurement times. However, cylinder sampling requires knowledge of a combined variable individual tree volume equation. Of the three variance reduction techniques applied to Ueno's method, antithetic variates performed best in computer simulation.

Ethanol in ponderosa pine as an indicator of physiological injury from fire and its relationship to secondary beetles

2003 ◽  
Vol 33 (5) ◽  
pp. 870-884 ◽  
Author(s):  
Rick G Kelsey ◽  
Gladwin Joseph
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Xylem Sap ◽  
Upward Movement ◽  
Stem Base ◽  
Breast Height ◽  
Dead Trees ◽  
Crown Scorch ◽  
Second Year ◽  
The Relationship

Sixteen days after a September wildfire, ethanol and water were measured in phloem and sapwood at breast height and the base of Pinus ponderosa Dougl. ex P. & C. Laws. with zero (control), moderate, heavy, and severe crown scorch. The quantity of ethanol increased with each level of injury, resulting in trees with severe scorch containing 15 and 53 times more phloem and sapwood ethanol, respectively, than controls. Ethanol concentrations in the sapwood and adjacent phloem were related, probably as a result of diffusion. Upward movement in xylem sap was most likely responsible for the relationship between sapwood ethanol concentrations at breast height and the stem base. As trees recovered from their heat injuries, the ethanol concentrations declined. In contrast, ethanol accumulated in dead trees that lost their entire crowns in the fire. Various bark and xylophagous beetles landed in greater numbers on fire-damaged trees than on controls the following spring and summer, suggesting that ethanol was being released to the atmosphere and influencing beetle behavior. Beetle landing was more strongly related to sapwood ethanol concentrations the previous September than in May. Sapwood ethanol measured 16 days after the fire was the best predictor of second-year mortality for trees with heavy and severe crown scorch.

The effect of spatially variable overstory on the understory light environment of an open-canopied longleaf pine forest

2002 ◽  
Vol 32 (11) ◽  
pp. 1984-1991 ◽  
Author(s):  
Michael A Battaglia ◽  
Pu Mou ◽  
Brian Palik ◽  
Robert J Mitchell
Keyword(s):  
Spatial Variation ◽  
Spatial Patterns ◽  
Longleaf Pine ◽  
Light Availability ◽  
Canopy Structure ◽  
Basal Area ◽  
Pinus Palustris ◽  
Pine Forest ◽  
Large Group ◽  
The Relationship

Spatial aggregation of forest structure strongly regulates understory light and its spatial variation in longleaf pine (Pinus palustris Mill.) forest ecosystems. Previous studies have demonstrated that light availability strongly influences longleaf pine seedling growth. In this study, the relationship between spatial structure of a longleaf pine forest and spatial pattern of understory light availability were investigated by comparing three retention harvest treatments: single-tree, small-group, large-group, and an uncut control. The harvests retained similar residual basal area but the spatial patterns of the residual trees differed. Hemispherical photographs were taken at 300 stations to calculate gap light index (GLI), an estimate of understory light availability. Stand-level mean, variation, and spatial distribution of GLI were determined for each treatment. By aggregating residual trees, stand mean GLI increased by 20%, as well as its spatial variation. Spatial autocorrelation of GLI increased as the size of the canopy gaps increased and the gaps were better defined; thus, the predictability of GLI was enhanced. The ranges of detrended semivariograms were increased from the control to the large-group harvest indicating the spatial patterns of understory GLI became coarser textured. Our results demonstrated that aggregated canopy structure of longleaf pine forest will facilitate longleaf pine seedling regeneration.

Exploring Spatial Patterns of Property Crime Risks in Changchun, China

2013 ◽  
Vol 4 (3) ◽  
pp. 80-100 ◽  
Author(s):  
Wei Song ◽  
Daqian Liu
Keyword(s):  
Spatial Patterns ◽  
Hot Spots ◽  
Property Crime ◽  
Ordinary Least Squares ◽  
Neighborhood Characteristics ◽  
Risk Areas ◽  
Gwr Model ◽  
The Relationship ◽  
The City ◽  
Crime Risks

Urban crime has increasingly become a major issue for Chinese cities. Using crime data collected at police precincts in 2008, the main aim of this research is to examine the spatial distribution of property crime which accounted for almost 82% of all crimes in the city of Changchun, and analyze the relationship between the spatial patterns of property crime and neighborhood characteristics. Standardized property crime rates (SCR) were applied to assess the relative risk of property crime across the city. Statistically significant clusters of high-risk areas or hot-spots were detected. A global ordinary least squares (OLS) regression model and a geographically weighted regression (GWR) model were calibrated to explore the risk of property crime as a function of contextual neighborhood characteristics. The analytical results show that significant local variations exist in the relationship between the risk of property crime and several neighborhood socioeconomic variables.

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