scholarly journals A parameter recovery model for estimating black spruce diameter distributions within the context of a stand density management diagram

2004 ◽  
Vol 80 (3) ◽  
pp. 349-358 ◽  
Author(s):  
P F Newton ◽  
Y. Lei ◽  
S Y Zhang
Keyword(s):  
Black Spruce ◽  
Stand Density ◽  
Seemingly Unrelated Regression ◽  
Parameter Estimates ◽  
Prediction Equations ◽  
Frequency Distributions ◽  
Unrelated Regression ◽  
Stand Density Management ◽  
Parameter Prediction ◽  
Stand Density Management Diagram

The objectives of this study were to develop and subsequently demonstrate a parameter prediction approach for estimating black spruce (Picea mariana (Mill. ) BSP) diameter frequency distributions within the context of a stand density management diagram (SDMD). The approach consisted of three sequential steps: (1) obtaining maximum likelihood estimates for the location, scale and shape parameters of the Weibull probability density function for 153 empirical diameter frequency distributions; (2) developing and evaluating parameter prediction equations in which the Weibull parameter estimates were expressed as functions of stand-level variables based on step-wise regression and seemingly unrelated regression techniques; and (3) explicitly incorporating the parameter prediction equations into the SDMD modelling framework. The results indicated that the Weibull function was successful in characterizing the diameter distributions within the sample stands: the fitted distributions exhibited no significant (p ≤ 0. 05) differences in relation to their corresponding observed distributions, based on the Kolmogorov-Smirnov test. The parameter prediction equations described 94, 94 and 89% of the variation in the location, scale and shape parameter estimates, respectively. Furthermore, evaluation of the recovered distributions in terms of prediction error indicated minimal biases and acceptable accuracy. As demonstrated, incorporating the parameter prediction equations into an algorithmic version of the SDMD enabled the prediction of the temporal dynamics of the diameter frequency distribution by initial density regime and site quality. Additionally, an executable version of the resultant algorithm with instructions on acquiring it via the Internet is provided. Key words: 3-parameter Weibull probability density function, stepwise and seemingly unrelated regression, predictive error, product value, algorithm, Internet

Stand density management diagram for managed black spruce stands

1994 ◽  
Vol 70 (1) ◽  
pp. 65-74 ◽  
Author(s):  
P. F. Newton ◽  
G. F. Weetman
Keyword(s):  
Black Spruce ◽  
Stand Density ◽  
Northern Ontario ◽  
Site Class ◽  
Permanent Sample Plots ◽  
Kalmia Angustifolia ◽  
Initial Spacing ◽  
Stand Density Management ◽  
Crown Closure ◽  
Stand Density Management Diagram

A stand density management diagram for managed black spruce (Picea mariana (Mill.) B.S.P.) stands was developed using data derived from 37 variable-size temporary and permanent sample plots, and 257 open-grown sample trees. The plots were situated within 15 plantations and 4 precommercially thinned stands located throughout central and western Newfoundland, north-western New Brunswick and northern Ontario. The basic components of the diagram included: (1) an approximate crown closure line (2) the self-thinning rule (3) expected size-density trajectories and (4) isolines for dominant height, relative density index, quadratic mean diameter and merchantability ratio. The utility of the diagram was demonstrated by deriving yields for various initial spacings by site class and subsequently evaluating various outcomes in terms of operability criteria. In addition, the potential of estimating the time of crown closure by initial spacing and site class is discussed in relation to minimizing the adverse effects of Kalmia angustifolia (L.) on black spruce growth and development. Key words: stand density management diagram, initial spacing, black spruce, operability, Kalmia angustifolia (L.)

scholarly journals Stand density management diagrams and their development and utility in black spruce management

1993 ◽  
Vol 69 (4) ◽  
pp. 421-430 ◽  
Author(s):  
P. F. Newton ◽  
G. F. Weetman
Keyword(s):  
Black Spruce ◽  
Basal Area ◽  
Stand Density ◽  
Future Research ◽  
Permanent Sample Plots ◽  
Quadratic Mean Diameter ◽  
Using Data ◽  
Stand Density Management ◽  
Natural Stands ◽  
Stand Density Management Diagram

A stand density management diagram for black spruce (Picea mariana (Mill.) B.S.P.) was developed using data derived from 49 0.081-ha permanent sample plots and 257 open-grown sample trees located throughout central insular Newfoundland. The diagram illustrated the reciprocal equation of the competition-density effect, self-thinning rule, approximate crown closure line, zone of imminent competition-mortality, and isolines for relative density, quadratic mean diameter and merchantability ratio. Mean prediction error for natural stand trajectories over a 30-projection period were 2.5 dm3 for mean volume, 306 stems/ha for density, 16.1 m3/ha for merchantable volume, 14.3 m3/ha for total volume, and 1.9 m2/ha for basal area. Implementation procedures using a combination of monoareal and polyareal sampling methods were described and the potential application of the diagram for evaluating thinning alternatives was demonstrated. Limitations of the diagram and future research directions were identified. Key words: stand density management diagram, black spruce, natural stands, central Newfoundland

scholarly journals Regional-Specific Algorithmic Stand Density Management Diagram for Black Spruce

1998 ◽  
Vol 15 (2) ◽  
pp. 94-97 ◽  
Author(s):  
Peter F. Newton
Keyword(s):  
Black Spruce ◽  
Initial Density ◽  
Basal Area ◽  
Stand Density ◽  
Site Specific ◽  
Yield Production ◽  
Number Of Stems ◽  
Stand Density Management ◽  
Time Required ◽  
Stand Density Management Diagram

Abstract A regional-specific algorithmic stand density management diagram was developed for managed upland black spruce (Picea mariana [Mill.] B.S.P.) stands applicable to Newfoundland, New Brunswick, Quebec, and Ontario. Specifically, the IBM-compatible PC-based algorithm (1) graphically illustrates site-specific size-density trajectories for 8 user-specified initial density regimes, (2) calculates and subsequently tabulates periodic yield estimates from 5-50 yr by 5 yr intervals for mean dominant height, density, mean volume, total volume, total merchantable volume, quadratic mean diameter, and basal area, (3) given (2), graphically illustrates empirically derived yield production curves for total merchantable volume per hectare and number of stems per cubic meter with user-specified operability criteria superimposed, and (4) given (3), calculates and subsequently tabulates the minimum time required to attain operability status. The utility of the algorithm is demonstrated within the context of determining site-specific initial densities required to attain user-specified operability criteria. Procedures for acquiring the executable version via the Internet are also included. North. J. Appl. For. 15(2):94-97.

scholarly journals Tree Biomass Equations for Naturally Regenerated Shortleaf Pine

2008 ◽  
Vol 32 (4) ◽  
pp. 163-167 ◽  
Author(s):  
Charles O. Sabatia ◽  
Thomas B. Lynch ◽  
Rodney E. Will
Keyword(s):  
Stand Density ◽  
Seemingly Unrelated Regression ◽  
Tree Level ◽  
Parameter Estimates ◽  
Pinus Echinata ◽  
Shortleaf Pine ◽  
Tree Biomass ◽  
Biomass Component ◽  
Tree Component ◽  
Old Trees

Abstract Aboveground tree-level and branch-level biomass component equations were fitted by nonlinear seemingly unrelated regression, for even-aged naturally regenerated shortleaf pine (Pinus echinata Mill.) in southeastern Oklahoma. Data were obtained from 46- to 53-year-old trees growing in stands that had previously been thinned to densities ranging from 50% of full stocking to overstocked unthinned stands. Stand density affected some of the parameter estimates for trees growing in thinned stands versus unthinned stands. Equations based on dbh alone gave biomass estimates that were not significantly different from those obtained with equations based on dbh, height, and/or crown width. The fitted tree-level biomass component equations were additive in the sense that predictions for biomass components were constrained by the estimation process to sum to total tree biomass. These equations can be used to estimate aboveground tree or tree component biomass for naturally regenerated shortleaf pine in the dbh range of 7–40 cm in southeastern Oklahoma and have potential for application in other shortleaf pine growing areas.

Algorithmic versions of black spruce stand density management diagrams

1997 ◽  
Vol 73 (2) ◽  
pp. 257-265 ◽  
Author(s):  
P. F. Newton
Keyword(s):  
Black Spruce ◽  
Initial Density ◽  
Basal Area ◽  
Stand Density ◽  
File Transfer ◽  
Quadratic Mean ◽  
Dominant Height ◽  
Yield Production ◽  
Quadratic Mean Diameter ◽  
Stand Density Management

Algorithmic versions of stand density management diagrams (SDMDs) were developed for natural and managed black spruce (Picea mariana (Mill.) B.S.P.) stands. Specifically, the IBM-compatible PC-based algorithms (1) graphically illustrate site-specific size-density trajectories for eight user-specified initial density regimes, (2) given (1), calculate and subsequent tabulate periodic yield estimates (mean dominant height, density, mean volume, total volume, total merchantable volume, quadratic mean diameter, and basal area), and (3) given (2), graphically illustrate empirically-derived yield production curves for total merchantable volume ha−1 and stems m−3 with user-specified operability criteria superimposed. Instructions on acquiring the executable algorithmic versions including the required graphical subroutines via the Internet are described. Currently, the algorithms are restricted in applicability to central insular Newfoundland. Key words: stand density management diagrams, black spruce, algorithms, microcomputer, World-Wide Web (WWW), hypertext browser, file transfer protocol (FTP).

Yield prediction errors of a stand density management program for black spruce and consequences for model improvement

2003 ◽  
Vol 33 (3) ◽  
pp. 490-499 ◽  
Author(s):  
P F Newton
Keyword(s):  
Prediction Error ◽  
Stand Structure ◽  
Black Spruce ◽  
Initial Density ◽  
Stand Density ◽  
Management Decision ◽  
Prediction Errors ◽  
Structure Variation ◽  
Model Improvement ◽  
Stand Density Management

The objectives of this study were to (i) quantify the prediction error associated with estimating density (N (stems/ha)), quadratic mean diameter (Dq (cm)), basal area (G (m2/ha)), total volume (Vt (m3/ha)), and merchantable volume (Vm (m3/ha)) using a stand density management decision-support program (SDMDSP) developed for black spruce (Picea mariana (Mill.) BSP) plantations and (ii) given objective i, assess model adequacy by examining the relationship between prediction error and model input variables (prediction period, site index, initial density, and number of thinning treatments) by yield variate. Specifically, the SDMDSP was evaluated by comparing its yield predictions with corresponding measured values (n = 44) within 19 black spruce plantations. The resultant tolerance intervals indicated that 95% of the relative errors associated with future predictions would be within the following limits 95% of the time (minimum–maximum): (i) –27.3 to 29.7% for N, (ii) –26.1 to 14.3% for Dq, (iii) –48.3 to 26.1% for G, (iv) –64.3 to 37.7% for Vt, and (v) –87.0 to 73.0% for Vm. Graphical analysis indicated that errors for Vt and Vm were associated with the data from thinned plantations. This result is discussed within the context of residual stand structure variation and response delay from which recommendations for model improvement are derived.

Border Zone Mass Transit Demad in Brownsville and Laredo

2012 ◽  
Vol 51 (2) ◽  
Author(s):  
Thomas M. Fullerton Jr ◽  
Adam G. Walke
Keyword(s):  
Exchange Rate ◽  
Real Exchange Rate ◽  
Public Transportation ◽  
Seemingly Unrelated Regression ◽  
Border Zone ◽  
Parameter Estimates ◽  
Border Crossings ◽  
The Real ◽  
Border City ◽  
Unrelated Regression

This study examines whether economic conditions in Mexico influence public transportation ridership levels in the border cities of Brownsville and Laredo, Texas. Besides the standard variables generally utilized to model bus ridership, additional indicators included in the empirical analysis are northbound pedestrian traffic and the real exchange rate index. Seemingly unrelated regression parameter estimates suggest that the volume of pedestrian border crossings in both cities is positively related to changes in ridership. The real exchange rate index in Laredo is negatively related to fluctuations in ridership, implying that peso appreciation increases transit utilization in this border city.

scholarly journals Stand Density Management Diagram for Jack Pine Stands in Eastern Canada

2007 ◽  
Vol 24 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Mahadev Sharma ◽  
S.Y. Zhang
Keyword(s):  
Pinus Banksiana ◽  
Stand Density ◽  
Jack Pine ◽  
Eastern Canada ◽  
Permanent Sample Plots ◽  
Quadratic Mean Diameter ◽  
Using Data ◽  
Stand Density Management ◽  
Crown Closure ◽  
Stand Density Management Diagram

Abstract A stand density management diagram was developed for jack pine (Pinus banksiana Lamb.) stands using the data obtained from 125 permanent sample plots (PSPs) established in Ontario and 232 PSPs in Quebec, Canada. The diagram was evaluated using data from 40 PSPs established in Ontario. Recently developed and efficient models have been used in constructing the diagram to estimate diameters and heights for the trees for which no diameters or heights were recorded at the time of stand inventory. Relative density indices of 0.15, 0.40, and 0.55 were used, corresponding to the line of approximate crown closure, the limit of productive zone, and the lower limit of competition-related mortality, respectively. If two stand characteristics are known, including mean total tree volume, quadratic mean diameter, trees per hectare, and average dominant height, the others can be readily obtained using the diagram. The consequences of various thinning scenarios can be plotted and visualized in the field without the need for computer simulation.

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