Editorial

2 pages, 620 KiB

Open AccessEditorial

Modeling Forest Stand Dynamics, Growth and Yield

by Harold E. Burkhart

Forests 2021, 12(11), 1553; https://0-doi-org.brum.beds.ac.uk/10.3390/f12111553 - 11 Nov 2021

Cited by 1 | Viewed by 1329

The world’s forests are diverse and serve myriad purposes; however, regardless of the management objective, reliable models of forest stand dynamics, growth and yield are required [...] Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

Research

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21 pages, 2388 KiB

Open AccessArticle

Modelling Tree Growth in Monospecific Forests from Forest Inventory Data

by Guadalupe Sáez-Cano, Marcos Marvá, Paloma Ruiz-Benito and Miguel A. Zavala

Forests 2021, 12(6), 753; https://0-doi-org.brum.beds.ac.uk/10.3390/f12060753 - 08 Jun 2021

Cited by 2 | Viewed by 2796

Abstract

The prediction of tree growth is key to further understand the carbon sink role of forests and the short-term forest capacity on climate change mitigation. In this work, we used large-scale data available from three consecutive forest inventories in a Euro-Mediterranean region and [...] Read more.

The prediction of tree growth is key to further understand the carbon sink role of forests and the short-term forest capacity on climate change mitigation. In this work, we used large-scale data available from three consecutive forest inventories in a Euro-Mediterranean region and the Bertalanffy–Chapman–Richards equation to model up to a decade’s tree size variation in monospecific forests in the growing stages. We showed that a tree-level fitting with ordinary differential equations can be used to forecast tree diameter growth across time and space as function of environmental characteristics and initial size. This modelling approximation was applied at different aggregation levels to monospecific regions with forest inventories to predict trends in aboveground tree biomass stocks. Furthermore, we showed that this model accurately forecasts tree growth temporal dynamics as a function of size and environmental conditions. Further research to provide longer term prediction forest stock dynamics in a wide variety of forests should model regeneration and mortality processes and biotic interactions. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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20 pages, 5701 KiB

Open AccessArticle

Modelling the Spatial Structure of White Spruce Plantations and Their Changes after Various Thinning Treatments

by Emmanuel Duchateau, Robert Schneider, Stéphane Tremblay, Laurie Dupont-Leduc and Hans Pretzsch

Forests 2021, 12(6), 740; https://0-doi-org.brum.beds.ac.uk/10.3390/f12060740 - 04 Jun 2021

Cited by 3 | Viewed by 1929

Abstract

Research Highlights: The spatial distribution of trees results from several ecological processes that can be difficult to measure. We applied a point process modelling approach that uses the diameter and species of neighbouring trees to represent inter-tree interactions through repulsive and attractive processes. [...] Read more.

Research Highlights: The spatial distribution of trees results from several ecological processes that can be difficult to measure. We applied a point process modelling approach that uses the diameter and species of neighbouring trees to represent inter-tree interactions through repulsive and attractive processes. Thinning treatments slightly influence the tree spatial distribution of trees in white spruce plantations. Integrating this “spatialiser” into growth models could help improve stand simulations following various thinning treatments over larger areas and longer periods. It could also allow for the use of spatially explicit models when tree position is not available. Background and Objectives: Tree spatial patterns result from several ecological processes and have important implications in forest ecology and management. The use of spatial information can significantly improve our understanding of forest structures. However, this implies intensive field work that is rarely integrated into forest inventories. The aims of this study were to develop a spatial distribution simulator of trees in white spruce plantations and to evaluate the influence of thinning treatments. Materials and Methods: A point process modelling approach was used to represent inter-tree interactions through repulsive and attractive process in white spruce (Picea glauca (Moench) Voss) plantations in eastern Quebec, Canada, that had been commercially thinned five years ago. Balsam fir (Abies balsamea (L.) Mill.) and hardwoods together can represent 30–40% of the basal area of these plantations. Results: The diameter and species of each tree’s two closest neighbours were found to be the most important predictors in explaining the observed distances between trees. Despite the short period since thinning treatments, results showed that the treatment had slight significant effects on tree interactions. However, their impact on the global spatial distribution of stands is quite limited. Conclusions: Using only a few readily-available variables (species and diameter of trees), this “spatialiser” will make it possible to assign spatial coordinates to trees and generate realistic stand spatial structures even after various silvicultural treatments. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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14 pages, 7626 KiB

Open AccessArticle

Research on Tree Pith Location in Radial Direction Based on Terrestrial Laser Scanning

by Yun Cao, Danyu Wang, Zewei Wang, Lijing Tian, Change Zheng, Ye Tian and Yi Liu

Forests 2021, 12(6), 671; https://0-doi-org.brum.beds.ac.uk/10.3390/f12060671 - 25 May 2021

Cited by 4 | Viewed by 1879

Abstract

Obtaining the direction of a diameter line through the tree pith is the basis of effective sampling by a micro-drill resistance instrument. In order to implement non-destructive tree pith location in the radial direction, the geometric property of tree pith, the longest chord [...] Read more.

Obtaining the direction of a diameter line through the tree pith is the basis of effective sampling by a micro-drill resistance instrument. In order to implement non-destructive tree pith location in the radial direction, the geometric property of tree pith, the longest chord through the tree pith on the cross-section will bisect outer contour circumference, as first proposed and proven in this paper. Based on this property, a non-destructive tree pith radial location method based on terrestrial laser scanning was developed. The experiments of pith radial location were made on the tree discs and the error of location is less than 1.5% for cross-section shape closed to ellipse on four tree species. The geometric property and location method of the tree pith in this research would play an important role in studying the growth process of standing trees, obtaining processed wood properties, and estimating tree age. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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29 pages, 1320 KiB

Open AccessArticle

A Dynamic Stand Growth Model System for Loblolly Pine Responding to Mid-Rotation Treatments

by Mauricio Zapata-Cuartas, Bronson P. Bullock, Cristian R. Montes and Michael B. Kane

Forests 2021, 12(5), 556; https://0-doi-org.brum.beds.ac.uk/10.3390/f12050556 - 29 Apr 2021

Cited by 5 | Viewed by 1986

Abstract

Intensive loblolly pine (Pinus taeda L.) plantation management in the southeastern United States includes mid-rotation silvicultural practices (MRSP) like thinning, fertilization, competitive vegetation control, and their combinations. Consistent and well-designed long-term studies considering interactions of MRSP are required to produce accurate projections [...] Read more.

Intensive loblolly pine (Pinus taeda L.) plantation management in the southeastern United States includes mid-rotation silvicultural practices (MRSP) like thinning, fertilization, competitive vegetation control, and their combinations. Consistent and well-designed long-term studies considering interactions of MRSP are required to produce accurate projections and evaluate management decisions. Here we use longitudinal data from the regional Mid-Rotation Treatment study established by the Plantation Management Research Cooperative (PMRC) at the University of Georgia across the southeast U.S. to fit and validate a new dynamic model system rooted in theoretical and biological principles. A Weibull pdf was used as a modifier function coupled with the basal area growth model. The growth model system and error projection functions were estimated simultaneously. The new formulation results in a compatible and consistent growth and yield system and provides temporal responses to treatment. The results indicated that the model projections reproduce the observed behavior of stand characteristics. The model has high predictive accuracy (the cross-validation variance explained was 96.2%, 99.7%, and 98.6%; and the prediction root mean square distance was 0.704 m, 19.1 trees ha⁻¹, and 1.03 m²ha⁻¹ for dominant height (

D H

), trees per hectare (N), and basal area (

B A

), respectively), and can be used to project the current stand attributes following combinations of MRSP and with different thinning intensities. Simulations across southern physiographic regions allow us to conclude that the most overall ranking of MRSP after thinning is fertilization + competitive vegetation control (Fert + CVC) > fertilization only (Fert) > competitive vegetation control only (CVC), and Fert + CVC show less than additive effect. Because of the model structure, the response to treatment changes with location, age of application, and dominant height growth as indicators of site quality. Therefore, the proposed model adequately represents regional growth conditions. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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21 pages, 4472 KiB

Open AccessArticle

Reducing the Uncertainty of Radiata Pine Site Index Maps Using an Spatial Ensemble of Machine Learning Models

by Gonzalo Gavilán-Acuña, Guillermo Federico Olmedo, Pablo Mena-Quijada, Mario Guevara, Beatriz Barría-Knopf and Michael S. Watt

Forests 2021, 12(1), 77; https://0-doi-org.brum.beds.ac.uk/10.3390/f12010077 - 11 Jan 2021

Cited by 10 | Viewed by 2769

Abstract

Site Index has been widely used as an age normalised metric in order to account for variation in forest height at a range of spatial scales. Although previous research has used a range of modelling methods to describe the regional variation in Site [...] Read more.

Site Index has been widely used as an age normalised metric in order to account for variation in forest height at a range of spatial scales. Although previous research has used a range of modelling methods to describe the regional variation in Site Index, little research has examined gains that can be achieved through the use of regression kriging or spatial ensemble methods. In this study, an extensive set of environmental surfaces were used as covariates to predict Site Index measurements covering the environmental range of Pinus radiata D. Don plantations in Chile. Using this dataset, the objectives of this research were to (i) compare predictive precision of a range of geostatistical, parametric, and non-parametric models, (ii) determine whether significant gains in precision can be attained through use of regression kriging, (iii) evaluate the precision of a spatial ensemble model that utilises predictions from the five most precise models, through using the model prediction with lowest error for a given pixel, and (iv) produce a map of Site Index across the study area. The five most precise models were all geostatistical and they included ordinary kriging and four regression kriging models that were based on partial least squares or random forests. A spatial ensemble model that was constructed from these five models was the most precise of those developed (RMSE = 1.851 m, RMSE% = 6.38%) and it had relatively little bias. Climatic and edaphic variables were the strongest determinants of Site Index and, in particular, variables that are related to soil water balance were well represented within the most precise predictive models. These results highlight the utility of predicting Site Index using a range of approaches, as these can be used to construct a spatial ensemble that may be more precise than predictions from the constituent models. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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14 pages, 2922 KiB

Open AccessArticle

A New Approach for Modeling Volume Response from Mid-Rotation Fertilization of Pinus taeda L. Plantations

by Henrique F. Scolforo, Cristian Montes, Rachel L. Cook, Howard Lee Allen, Timothy J. Albaugh, Rafael Rubilar and Otavio Campoe

Forests 2020, 11(6), 646; https://0-doi-org.brum.beds.ac.uk/10.3390/f11060646 - 06 Jun 2020

Cited by 5 | Viewed by 2043

Abstract

Mid-rotation fertilization presents an opportunity to increase the economic return of plantation forests in the southeastern United States (SEUS). For this reason, the Forest Productivity Cooperative established a series of mid-rotation fertilization trials in Pinus taeda L. plantations across the SEUS between 1984 [...] Read more.

Mid-rotation fertilization presents an opportunity to increase the economic return of plantation forests in the southeastern United States (SEUS). For this reason, the Forest Productivity Cooperative established a series of mid-rotation fertilization trials in Pinus taeda L. plantations across the SEUS between 1984 and 1987. These trials identified site-specific responses to nitrogen (N) and phosphorus (P) fertilizers, resulting in increased stand production for 6–10 years after fertilization. There are successful volume response models that allow users to quantify the gain in stand productivity resulting from fertilization. However, all the current models depend on empirical relationships that are not bounded by biological response, meaning that greater fertilizer additions continue to create more volume gains, regardless of physiological limits. To address this shortcoming, we developed a bounded response model that evaluates relative volume response gain to fertilizer addition. Site index and relative spacing are included as model parameters to help provide realistic estimates. The model is useful for evaluating productivity gain in Pinus taeda stands that are fertilized with N and P in mid-rotation. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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20 pages, 3658 KiB

Open AccessArticle

Meta-Modelling to Quantify Yields of White Spruce and Hybrid Spruce Provenances in the Canadian Boreal Forest

by Suborna Ahmed, Valerie LeMay, Alvin Yanchuk, Andrew Robinson, Peter Marshall and Gary Bull

Forests 2020, 11(6), 609; https://0-doi-org.brum.beds.ac.uk/10.3390/f11060609 - 28 May 2020

Cited by 1 | Viewed by 2807

Abstract

Tree improvement programs can improve forest management by increasing timber yields in some areas, thereby facilitating conservation of other forest lands. In this study, we used a meta-analytic approach to quantify yields of alternative white (Picea glauca (Moench) Voss) and hybrid spruce [...] Read more.

Tree improvement programs can improve forest management by increasing timber yields in some areas, thereby facilitating conservation of other forest lands. In this study, we used a meta-analytic approach to quantify yields of alternative white (Picea glauca (Moench) Voss) and hybrid spruce (Picea engelmannii Parry ex Engelmann x Picea glauca (Moench) Voss) stocks across planting sites in the boreal and hemiboreal forests of Canada. We extracted meta-data from published tree improvement program results for five Canadian provinces covering 38 planting sites and 330 white and hybrid spruce provenances. Using these meta-data and a random-coefficients nonlinear mixed-effects modelling approach, we modelled average height over time trajectories for varying planting site characteristics, as well as climate transfer distances between planting sites and provenances. Climatic transfer distances had strong effects on the height trajectory parameters. In particular, the asymptote parameter had a nonlinear increasing trend with planting site versus provenance mean annual temperature differences. We incorporated the height trajectory meta-analysis model into an existing growth and yield model to predict volume yields. Overall, this research provides a mechanism to quantify yields of alternative provenances at a particular planting site, as a component of decision support models for evaluating evaluate forest management investment into improved planting stocks alternatives under current and possible future climates. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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25 pages, 4275 KiB

Open AccessArticle

Development of Nonlinear Parsimonious Forest Models Using Efficient Expansion of the Taylor Series: Applications to Site Productivity and Taper

by Alexandru Amarioarei, Mihaela Paun and Bogdan Strimbu

Forests 2020, 11(4), 458; https://0-doi-org.brum.beds.ac.uk/10.3390/f11040458 - 18 Apr 2020

Cited by 4 | Viewed by 2420

Abstract

The parameters of nonlinear forest models are commonly estimated with heuristic techniques, which can supply erroneous values. The use of heuristic algorithms is partially rooted in the avoidance of transformation of the dependent variable, which introduces bias when back-transformed to original units. Efforts [...] Read more.

The parameters of nonlinear forest models are commonly estimated with heuristic techniques, which can supply erroneous values. The use of heuristic algorithms is partially rooted in the avoidance of transformation of the dependent variable, which introduces bias when back-transformed to original units. Efforts were placed in computing the unbiased estimates for some of the power, trigonometric, and hyperbolic functions since only few transformations of the predicted variable have the corrections for bias estimated. The approach that supplies unbiased results when the dependent variable is transformed without heuristic algorithms, but based on a Taylor series expansion requires implementation details. Therefore, the objective of our study is to investigate the efficient expansion of the Taylor series that should be included in applications, such that numerical bias is not present. We found that five functions require more than five terms, whereas the arcsine, arccosine, and arctangent did not. Furthermore, the Taylor series expansion depends on the variance. We illustrated the results on two forest modeling problems, one at the stand level, namely site productivity, and one at individual tree level, namely taper. The models that are presented in the paper are unbiased, more parsimonious, and they have a RMSE comparable with existing less parsimonious models. Full article

(This article belongs to the Special Issue Modeling Forest Stand Dynamics, Growth and Yield)

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