A Validation of TWIGS for Illinois Forests

Abstract The predictive ability of the Central States growth and yield system TWIGS 3.0 was evaluated for Illinois forests. The data used to validate the system were collected from permanent plots that had been established throughout the state and maintained for up to 30 years. TWIGS growth predictions were analyzed through the differences between observed and predicted stand and species characteristics. TWIGS consistently overpredicted mean stand diameter and underpredicted tree survival over a 30-year growth projection. The combined result of prediction errors in diameter growth and tree survival was a consistent underprediction of basal area per acre. Percent error at the twentieth year of projection was -6% for mean stand diameter, 18% for tree survival, and 6% for basal area. TWIGS, with its simulation features and small relative prediction errors for some major timber species, is an adequate growth and yield system for Illinois' mixed hardwood forests. North. J. Appl. For. 6:154-156, December 1989.

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Stand-Level Components of a Growth and Yield Model for Nothofagus Mixed Forests from Southern Chile

Forests ◽

10.3390/f11080810 ◽

2020 ◽

Vol 11 (8) ◽

pp. 810

Author(s):

Sebastian Palmas ◽

Paulo C. Moreno ◽

Wendel P. Cropper ◽

Alicia Ortega ◽

Salvador A. Gezan

Keyword(s):

Forest Type ◽

Geographical Area ◽

Basal Area ◽

Forest Growth ◽

Model Systems ◽

Growth And Yield ◽

Permanent Plots ◽

Stand Age ◽

Yield Model ◽

Mixed Forests

Reliable information on stand dynamics and development is needed to improve management decisions on mixed forests, and essential tools for this purpose are forest growth and yield (G&Y) models. In this study, stand-level G&Y models were built for cohorts within the natural mixed second-growth Nothofagus-dominated forests in Chile. All currently available (but limited) data, consisting of a series of stratified temporary and permanent plots established in the complete range of this forest type, were used to fit and validate these models. Linear and nonlinear models were considered, where dominant stand age, number of trees, and the proportion of basal area of Nothofagus species resulted in significant predictors to project future values of stand basal area for the different cohorts (with R2 > 0.51 for the validation datasets). Mortality was successfully modeled (R2 = 0.79), based on a small set of permanent plots, using the concept of self-thinning with a proposed model defined by the idea that, as stands get closer to a maximum density, they experience higher levels of mortality. The evaluation of these models indicated that they adequately represent the current understanding of dynamics of basal area and mortality of Nothofagus and companion species in these forests. These are the first models fitted over a large geographical area that consider the dynamics of these mixed forests. It is suggested that the proposed models should constitute the main components of future implementations of G&Y model systems.

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A Whole-Stand Growth and Yield Model for Interior Douglas-Fir

Western Journal of Applied Forestry ◽

10.1093/wjaf/8.4.120 ◽

1993 ◽

Vol 8 (4) ◽

pp. 120-125 ◽

Cited By ~ 6

Author(s):

Lianjun Zhang ◽

James A. Moore ◽

James D. Newberry

Keyword(s):

Prediction Model ◽

Model Simulation ◽

Growth Models ◽

Basal Area ◽

Height Growth ◽

Douglas Fir ◽

Growth And Yield ◽

Yield Model ◽

Projection System ◽

Tree Survival

Abstract A whole-stand model, Simulation Of Stands (SOS), was developed for even-aged Douglas-fir (Pseudotsuga menziesii var. glauca) stands in the inland Northwest. The model consists of three new components: (1) volume prediction model, (2) basal area prediction model, and (3) survival model. Existing height growth models were used to estimate stand top height growth. The behavior and performance of SOS were evaluated by simulating stand development over time under alternative conditions and comparing the results with growth and yield concepts suggested in the literature. The predicted stand attributes from SOS were also compared with predictions from the Stand Prognosis Model and Stand Projection System (SPS). SOS behavior was similar to Prognosis for lower site indices, but more like SPS for higher site indices. The three models differed mainly with respect to stand top height growth and tree survival. West. J. Appl. For. 8(4):120-125.

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Partial Calibration of "ONTWIGS": A Forest Growth and Yield Projection System Adapted for Ontario

Northern Journal of Applied Forestry ◽

10.1093/njaf/11.2.41 ◽

1994 ◽

Vol 11 (2) ◽

pp. 41-46 ◽

Cited By ~ 3

Author(s):

Bijan Payandeh ◽

Pia Papadopol

Keyword(s):

Basal Area ◽

Forest Growth ◽

Data Sets ◽

Prediction Errors ◽

Northern Ontario ◽

Quadratic Mean ◽

Tree Survival ◽

Mean Diameter ◽

Quadratic Mean Diameter ◽

Stand Attributes

Abstract "ONTWIGS" (an adaptation of "LSTWIGS" for Ontario), was partially calibrated for permanent plots data sets from northern Ontario. Stand attributes used for calibration were quadratic mean diameter, number of trees, and basal area/ha. Simple local calibration was accomplished by adjusting tree survival and potential diameter growth coefficients so as to reduce the prediction errors to within 10% of the actual values over a 5-yr period. This resulted in prediction errors ranging from -9.9 to 6.9%, but with an overall average of only: -1.4, 1.0, and 0.2% for the spruce fir data; from -8.5 to 2.8%, but with an overall average of only -0.7, 0.5, and 0.4% for a black spruce drainage and fertilization experiment; and from -6.6 to 9.8%, but with an overall average of only -1.7, 0.0, and -1.8% for an unthinned red pine plantation for number of trees/ha, quadratic mean diameter, and basal area/ha, respectively. Results indicate that "ONTWIGS" may be locally calibrated through simple procedures to increase its prediction accuracy to ±5% of the observed stand attributes, averaging less than 3% for the major timber species in northern Ontario and for short to medium projection periods. However, the uncalibrated model should be used with caution for short terms, only and where no other projection tools are available. More extensive calibrations of "ONTWIGS" on larger and more representative data sets are currently underway. North. J. Appl. For. 11(2):41-46.

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Croissance de sapinières à bouleau blanc boréales issues de coupe avec protection de la régénération

Canadian Journal of Forest Research ◽

10.1139/x92-224 ◽

1992 ◽

Vol 22 (11) ◽

pp. 1701-1711 ◽

Cited By ~ 1

Author(s):

Lucie Bertrand ◽

Louis Bélanger ◽

Robert L. Beauregard

Keyword(s):

Natural Regeneration ◽

Basal Area ◽

Balsam Fir ◽

Growth And Yield ◽

Permanent Plots ◽

White Birch ◽

Second Growth ◽

Harvesting Method ◽

Volume Production ◽

Rotation Age

Models of compatible volume and basal area growth and yield covering a period of 10 to 45 years after harvesting were developed for second growth boreal stands of balsam fir (Abiesbalsamea (L.) Mill.). The 131 permanent plots used for the study were located near Matane, in the Gaspé Peninsula, and are part of the balsam fir–white birch ecoclimatic domain. These stands were harvested in 1934, 1944, and 1953, using a manual cut-and-bunch harvesting method that protected advance growth, and measures were taken in 1954, 1964, and 1978. The stands were moderately affected by spruce budworm outbreaks between 1950–1957 and 1975–1978. Years elapsed since release rather than total age was used as the temporal variable. Even though the characteristics of the coniferous natural regeneration were quite variable, total basal area explained an important part of growth variations of young fir stands by integrating both density and dimensions of the regeneration. Results show, within the limits of the observed densities (< 15 000 stems/ha, 10 years after harvesting), that stands with a higher basal area will have higher total and merchantable volumes at a given age; rotation age for maximum volume production will decrease correspondingly. Abundance of saplings in the initial natural regeneration can thus have an important impact on stand production and rotation age. In the case of nonoverdense young fir stands (< 15 000 stems/ha, 10 years after harvesting with no height growth impediment), the use of spacing treatments that significantly reduce total basal area could be questioned when pursuing maximum fiber production.

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Sustainability of High-Value Timber Species in Mixed Conifer–Broadleaf Forest Managed under Selection System in Northern Japan

Forests ◽

10.3390/f11050484 ◽

2020 ◽

Vol 11 (5) ◽

pp. 484

Author(s):

Kyaw Thu Moe ◽

Toshiaki Owari

Keyword(s):

Mixed Forest ◽

Basal Area ◽

Basal Area Increment ◽

Diameter Distribution ◽

Permanent Plots ◽

Timber Species ◽

Selection System ◽

Management Options ◽

Species Proportions ◽

Northern Japan

Understanding the sustainability of high-value timber species in managed forests provides useful information for the management of these species in the long-run. Using nearly 50 years of census data in long-term permanent plots, we investigated the sustainability of three high-value timber species—monarch birch (Betula maximowicziana Regel), castor aralia (Kalopanax septemlobus (Thunb.) Koidz), and Japanese oak (Quercus crispula Blume)—in cool-temperate mixed forest under a selection system in northern Japan. We used stocking, demographic parameters, and species proportions of these species as measures of sustainability. Results showed that the tree density and basal area of the three high-value timber species increased during the study period. Moreover, the basal area increment of these species showed an increasing trend across census periods. However, while no significant differences in the tree mortality of these species were observed, the numbers of in-growth fluctuated across census periods. Increasing trends in species proportions of monarch birch and Japanese oak were observed. Even though there were some fluctuations across census periods, especially in smaller diameter classes, diameter distribution curves of high-value timber species followed a reversed J-shaped pattern. The results revealed that the sustainability measures of high-value timber species can be achieved in forest stands managed under single-tree selection system. In addition, the results also indicated the changing structure and composition of the forest stand. The stocking and basal area increment of conifers decreased while those of broadleaves increased. The proportion of conifers decreased to 33.01% in 2008–2016 from 48.35% in 1968–1978. The results of this study would be useful for adapting silvicultural practices and harvesting practices as well as for simulating various silvicultural and management options for high-value timber species.

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Testing the Accuracy of Growth and Yield Models for Southern Hardwood Forests

Southern Journal of Applied Forestry ◽

10.1093/sjaf/24.3.176 ◽

2000 ◽

Vol 24 (3) ◽

pp. 176-185 ◽

Cited By ~ 8

Author(s):

H. Michael Rauscher ◽

Michael J. Young ◽

Charles D. Webb ◽

Daniel J. Robison

Keyword(s):

Test Data ◽

Basal Area ◽

Hardwood Forests ◽

Growth And Yield ◽

Bottomland Hardwoods ◽

Average Error ◽

Yellow Poplar ◽

Data Set ◽

Southern Appalachian ◽

Growth And Yield Models

Abstract The accuracy of ten growth and yield models for Southern Appalachian upland hardwood forests and southern bottomland forests was evaluated. In technical applications, accuracy is the composite of both bias (average error) and precision. Results indicate that GHAT, NATPIS, and a locally calibrated version of NETWIGS may be regarded as being operationally valid growth and yield models for Southern Appalachian yellow-poplar (Liriodendron tulipifera) and mixed oak (Quercus spp.) forests that fall within the range of characteristics of the test data set. No publicly available growth and yield models specifically developed for southern bottomland hardwood forests exist. Four general models that contain most of the applicable species to predict growth of these forests were tested. SETWIGS was found to be the most accurate of the four models tested and is recommended for use if the reported level of accuracy is acceptable and the target stand characteristics fall within the range of our test data set. Results indicate that the growth and density dynamics of dense, young stands of both upland and bottomland hardwoods were poorly predicted by the models. Models predicted basal area and density changes in yellow-poplar stands more accurately than mixed hardwoods. Predictions for upland hardwoods were more accurate than those for bottomland hardwoods. Model accuracy uniformly decreases with increasing length of the projection period. South. J. Appl. For. 24(3):176-185.

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Modeling annualized occurrence, frequency, and composition of ingrowth using mixed-effects zero-inflated models and permanent plots in the Acadian Forest Region of North America

Canadian Journal of Forest Research ◽

10.1139/x11-117 ◽

2011 ◽

Vol 41 (10) ◽

pp. 2077-2089 ◽

Cited By ~ 33

Author(s):

Rongxia Li ◽

Aaron R. Weiskittel ◽

John A. Kershaw

Keyword(s):

North America ◽

Random Effects ◽

Negative Binomial ◽

Basal Area ◽

Forest Growth ◽

Occurrence Frequency ◽

Growth And Yield ◽

Permanent Plots ◽

Forest Region ◽

Acadian Forest

Forest tree ingrowth is a highly variable and largely stochastic process. Consequently, predicting occurrence, frequency, and composition of ingrowth is a challenging task but of great importance in long-term forest growth and yield model projections. However, ingrowth data often require different statistical techniques other than traditional Gaussian regression, because these data are often bounded, skewed, and non-normal and commonly contain a large fraction of zeros. This study presents a set of regression models based on discrete Poisson and negative binomial probability distributions for ingrowth data collected from permanent sample plots in the Acadian Forest Region of North America. Models considered here include regular Poisson, zero-inflated Poisson (ZIP), zero-altered Poisson (ZAP; hurdle Poisson), regular negative binomial (NB), zero-inflated negative binomial (ZINB), and zero-altered negative binomial (ZANB; hurdle NB). Plot-level random effects were incorporated into each of these models. The ZINB model with random effects was found to provide the best fit statistics for modeling annualized occurrence and frequency of ingrowth. The key explanatory variables were stand basal area per hectare, percentage of hardwood basal area, number of trees per hectare, a measure of site quality, and the minimum measured diameter at breast height of each plot. A similar model was developed to predict species composition. All models showed logical behavior despite the high variability observed in the original data.

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The SOHARC Model System for Growth and Yield of Southern Hardwoods

Southern Journal of Applied Forestry ◽

10.1093/sjaf/32.4.173 ◽

2008 ◽

Vol 32 (4) ◽

pp. 173-183 ◽

Cited By ~ 4

Author(s):

John Paul McTague ◽

David O'Loughlin ◽

Joseph P. Roise ◽

Daniel J. Robison ◽

Robert C. Kellison

Keyword(s):

Tree Growth ◽

Growth Models ◽

Basal Area ◽

Tree Height ◽

Growth And Yield ◽

Permanent Plots ◽

Red Maple ◽

Yellow Poplar ◽

Individual Tree ◽

Individual Tree Growth

Abstract A system of stand level and individual tree growth-and-yield models are presented for southern hardwoods. These models were developed from numerous permanent growth-and-yield plots established across 13 states in the US South on 9 site types, in even-aged (age classes from 20 to 60 years), fully stocked, naturally regenerated mixed hardwood and mixed hardwood-pine stands. Nested plots (⅕ and ac) were remeasured at 5-year intervals. The system of permanent plots was established and maintained by private and public members in the North Carolina State University Hardwood Research Cooperative. Stand level models are presented for dominant height, survival, basal area prediction and projection, and the ingrowth component. Individual tree diameter growth and tree height models were constructed for the most common species: sweetgum, tupelo, yellow-poplar, blackgum, and red maple. All other species were grouped according to growth dynamics into four species groups using cluster analysis. A ranking variable was incorporated into the individual tree growth models to account for competition.

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Evaluation of distance-independent competition indices in predicting tree survival and diameter growth

Canadian Journal of Forest Research ◽

10.1139/cjfr-2018-0344 ◽

2019 ◽

Vol 49 (5) ◽

pp. 440-446 ◽

Cited By ~ 5

Author(s):

Shuaichao Sun ◽

Quang V. Cao ◽

Tianjian Cao

Keyword(s):

Loblolly Pine ◽

Relative Position ◽

Basal Area ◽

Diameter Ratio ◽

Cumulative Distribution ◽

Permanent Plots ◽

Diameter Growth ◽

Individual Tree ◽

Tree Survival ◽

Competition Indices

Competition indices play a significant role in modeling individual-tree growth and survival. In this study, six distance-independent competition indices were evaluated using 200 permanent plots of loblolly pine (Pinus taeda L.). The competition indices were classified into three families: (1) size ratios, which include diameter ratio and basal area ratio; (2) relative position indices, which include basal area of larger trees (BAL) and tree relative position based on the cumulative distribution function (CDF); and (3) partitioned stand density index and relative density. Results indicated that different families of competition indices were suitable for different tree survival or diameter growth prediction tasks. The diameter ratio was superior for predicting tree survival, whereas the relative position indices (BAL and CDF) performed best for predicting tree diameter growth, with CDF receiving the highest rank.

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GROWTH AND YIELD OF EVEN-AGED Cupressus lusitanica PLANTATIONS IN SOUTHERN BRAZIL

FLORESTA ◽

10.5380/rf.v51i4.75135 ◽

2021 ◽

Vol 51 (4) ◽

pp. 980

Author(s):

Mário Dobner Jr.

Keyword(s):

Basal Area ◽

Site Index ◽

Growth And Yield ◽

Site Quality ◽

Timber Species ◽

Southern Brazil ◽

Cupressus Lusitanica ◽

Dominant Height ◽

Dominant Height Growth ◽

Quality Variation

Plantation forestry in southern Brazil demands additional timber species to a higher market differentiation by providing high quality timber and exploitation of market niches. Cupressus lusitanica has long been recognized for this purpose but, until now, it was not properly region-wide quantified in terms of growth and yield. The present study delivers the lacking quantitative approach, which may encourage the commercial use of the species. With this study it was aimed at collecting and processing quantitative data from all known C. lusitanica stands in southern Brazil. Inventories were carried out (60 ha, 6-39 years of age) in order to model the development of dominant height (h100), basal area, volume and dominant diameter (d100). Dominant height was the basis for site quality evaluation, delivering site index curves, which, together with the commercial volume of the stands, allowed yield modelling. A wide amplitude of dominant height growth was detected (10-30 m at 20 years), indicating a great site quality variation. At age of 20 years, commercial volumes of 110 and 620 m³ ha-1 were observed for site indexes of 14 and 26, respectively, equivalent to a maximum of 6-31 m³ ha-1 year-1 at ages between 16-18 years. Results demonstrated in a robust manner that C. lusitanica has a high potential for cultivation in southern Brazil. Thus, offering the opportunity of market differentiation by promoting market niches whose demands timber for special solid end-uses.

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