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.

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).

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 Croplanner: A Stand Density Management Decision-Support Software Suite for Addressing Volumetric Yield, End-Product and Ecosystem Service Objectives When Managing Boreal Conifers

Forests ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 448
Author(s):  
Peter F. Newton
Keyword(s):  
Decision Support ◽  
Black Spruce ◽  
Stand Density ◽  
Jack Pine ◽  
Management Decision ◽  
Software Suite ◽  
Crop Planning ◽  
Pine Stands ◽  
Stand Density Management ◽  
Support Software

The objectives of this study were to develop a stand density management decision-support software suite for boreal conifers and demonstrate its potential utility in crop planning using practical deployment exemplifications. Denoted CPDSS (CroPlanner Decision-support Software Suite), the program was developed by transcribing algorithmic analogues of structural stand density management diagrams previously developed for even-aged black spruce (Picea mariana (Mill) BSP.) and jack pine (Pinus banksiana Lamb.) stand-types into an integrated software platform with shared commonalities with respect to computational structure, input requirements and generated numerical and graphical outputs. The suite included 6 stand-type-specific model variants (natural-origin monospecific upland black spruce and jack pine stands, mixed upland black spruce and jack pine stands, and monospecific lowland black spruce stands, and plantation-origin monospecific upland black spruce and jack pine stands), and 4 climate-sensitive stand-type-specific model variants (monospecific upland black spruce and jack pine natural-origin and planted stands). The underlying models which were equivalent in terms of their modular structure, parameterization analytics and geographic applicability, were enabled to address a diversity of crop planning scenarios when integrated within the software suite (e.g., basic, extensive, intensive and elite silvicultural regimes). Algorithmically, the Windows® (Microsoft Corporation, Redmond, WA, USA) based suite was developed by recoding the Fortran-based algorithmic model variants into a collection of VisualBasic.Net® (Microsoft Corporation, Redmond, WA, USA) equivalents and augmenting them with intuitive graphical user interfaces (GUIs), optional computer-intensive optimization applications for automated crop plan selection, and interactive tabular and charting reporting tools inclusive of static and dynamic stand visualization capabilities. In order to address a wide range of requirements from the end-user community and facilitate potential deployment within provincially regulated forest management planning systems, a participatory approach was used to guide software design. As exemplified, the resultant CPDSS can be used as an (1) automated crop planning searching tool in which computer-intensive methods are used to find the most appropriate precommercial thinning, commercial thinning and (or) initial espacement (spacing) regime, according to a weighted multivariate scoring metric reflective of attained mean tree size, operability status, volumetric productivity, and economic viability, and a set of treatment-related constraints (e.g., thresholds regarding intensity and timing of thinning events, and residual stocking levels), as specified by the end-user, or (2) iterative gaming-like crop planning tool where end-users simultaneously contrast density management regimes using detailed annual and rotational volumetric yield, end-product and ecological output measures, and (or) an abbreviate set of rotational-based performance metrics, from which they determine the most applicable crop plan required for attaining their specified stand-level objective(s). The participatory approach, modular computational structure and software platform used in the formulation of the CPDSS along with its exemplified utility, collectively provides the prerequisite foundation for its potential deployment in boreal crop planning.

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 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

scholarly journals Stand Density Management Diagram for Mixed Balsam Fir-Black Spruce Stands

1998 ◽  
Vol 15 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Brian R. Sturtevant ◽  
John A. Bissonett ◽  
James N. Long
Keyword(s):  
Black Spruce ◽  
Rotation Period ◽  
Stand Density ◽  
Balsam Fir ◽  
Data Set ◽  
Treatment Scenario ◽  
Spruce Stands ◽  
Permanent Sample Plot ◽  
Using Data ◽  
Stand Density Management

Abstract Stand density management diagrams (SDMDs) provide a useful means of predicting the consequences of alternative density management regimes. The specific objectives of this project were to create a SDMD that could (a) be applied to mixed balsam fir-black spruce stands, and (b) allow structural predictions beyond the typical 60 yr pulpwood rotation period. We constructed the SDMD using data from 129 horizontal point samples from 24 stands and 17 permanent sample plot measurements within 9 stands, located in western and central Newfoundland. The model has not been tested with an independent data set, and should therefore be viewed as a first approximation. We further discuss the diagram's applicability, and provide an example of its utility by demonstrating a precommercial thinning treatment versus no treatment scenario. North. J. Appl. For. 15(1):17-22.

A stand density management diagram for spruce–balsam fir mixtures in New Brunswick

2007 ◽  
Vol 83 (2) ◽  
pp. 187-197 ◽  
Author(s):  
Edwin Swift ◽  
Margaret Penner ◽  
Rolland Gagnon ◽  
Jason Knox
Keyword(s):  
Species Composition ◽  
New Brunswick ◽  
Stand Structure ◽  
Abies Balsamea ◽  
Stand Density ◽  
Forest Products ◽  
Balsam Fir ◽  
Mixed Stands ◽  
Pure Species ◽  
Stand Density Management

Balsam fir (Abies balsamea (L.) Mill.), red spruce (Picea rubens Sarg.), black spruce (P. mariana (Mill.) BSP), and white spruce (P. glauca (Moench) Voss) often form mixed stands throughout northeastern North America. After harvesting operations or natural disturbances, the resulting natural regeneration may require thinning prescriptions to achieve the desired future stand structure and associated forest products. Stand density management diagrams (SDMDs) can assist the forest manager in examining potential yield implications of stand density management decisions. Data from New Brunswick, Nova Scotia, and Quebec indicate a single SDMD is not appropriate for mixtures of balsam fir and spruce (red and black). The maximum size density line is flatter for mixtures than for pure species stands and the quadratic mean diameter isolines are affected by the species composition. The top height isolines are independent of species composition. The results indicate the SDMD for spruce–balsam fir mixtures needs to be dynamic, incorporating the species proportions. The SDMD has been incorporated into software that prompts the user for the balsam fir fraction and generates the appropriate SDMD. Key words: Acadian Forest Region, eastern species mixtures, thinning decisions

scholarly journals Gender differences in refraction prediction error of five formulas for cataract surgery

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yibing Zhang ◽  
Tingyang Li ◽  
Aparna Reddy ◽  
Nambi Nallasamy
Keyword(s):  
Gender Differences ◽  
Cataract Surgery ◽  
Prediction Error ◽  
Statistical Difference ◽  
Independent Predictor ◽  
Study Data ◽  
Prediction Errors ◽  
Optical Biometry ◽  
Iol Power ◽  
Lens Power

Abstract Objectives To evaluate gender differences in optical biometry measurements and lens power calculations. Methods Eight thousand four hundred thirty-one eyes of five thousand five hundred nineteen patients who underwent cataract surgery at University of Michigan’s Kellogg Eye Center were included in this retrospective study. Data including age, gender, optical biometry, postoperative refraction, implanted intraocular lens (IOL) power, and IOL formula refraction predictions were gathered and/or calculated utilizing the Sight Outcomes Research Collaborative (SOURCE) database and analyzed. Results There was a statistical difference between every optical biometry measure between genders. Despite lens constant optimization, mean signed prediction errors (SPEs) of modern IOL formulas differed significantly between genders, with predictions skewed more hyperopic for males and myopic for females for all 5 of the modern IOL formulas tested. Optimization of lens constants by gender significantly decreased prediction error for 2 of the 5 modern IOL formulas tested. Conclusions Gender was found to be an independent predictor of refraction prediction error for all 5 formulas studied. Optimization of lens constants by gender can decrease refraction prediction error for certain modern IOL formulas.

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