Modelling Continuous Cover Forests

Vanclay, Jerome K.

doi:10.1007/978-94-007-2202-6_7

Cited by 7 publications

(4 citation statements)

References 51 publications

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“…where ln is the natural logarithm, Δd i is the diameter increment (cm • yr −1 ) of tree i, DBH is the diameter at breast height (cm) of tree i calculated for the middle of the interval (Vanclay 1994, p. 158), BAL is the basal area in larger trees (m 2 • ha −1 ) of tree i, G is the plot basal area (m 2 • ha −1 ), and β i are the estimated parameters. This is an easily fit and robust model whose trend line is very similar to those of other models that represent the biological behavior of the diameter increment (Vanclay 2012). A value of 0.2 was added when fitting the diameter increment to accommodate negative or zero increments (common in tropical forests) and enable the logarithmic transformation of null and negative values, because omitting these observations would have introduced bias and resulted in overestimates of the diameter increment (Vanclay 1991a).…”

Section: Sub-models To Predict Forest Dynamicsmentioning

confidence: 96%

Predicting the dynamics of a native Araucaria forest using a distance-independent individual tree-growth model

et al. 2016

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Background: In recent decades, native Araucaria forests in Brazil have become fragmented due to the conversion of forest to agricultural lands and commercial tree plantations. Consequently, the forest dynamics in this forest type have been poorly investigated, as most fragments are poorly structured in terms of tree size and diversity. Methods: We developed a distance-independent individual tree-growth model to simulate the forest dynamics in a native Araucaria forest located predominantly in southern Brazil. The data were derived from 25 contiguous plots (1 ha) established in a protected area left undisturbed for the past 70 years. The plots were measured at 3-year intervals from their establishment in 2002. All trees above a 10-cm diameter at breast height were tagged, identified as to species, and measured. Because this forest type comprises hundreds of tree species, we clustered them into six ecological groups: understory, subcanopy, upper canopy shade-tolerant, upper canopy light-demanding, pioneer, and emergent. The diameter increment, survival, and recruitment sub-models were fitted for each species group, and parameters were implemented in a simulation software to project the forest dynamics. The growth model was validated using independent data collected from another research area of the same forest type. To simulate the forest dynamics, we projected the species group and stand basal areas for 50 years under three different stand-density conditions: low, average, and high. Results: Emergent species tended to grow in basal area, irrespective of the forest density conditions. Conversely, shade-tolerant species tended to decline over the years. Under low-density conditions, the model showed a growth tendency for the stand basal area, while under average-density conditions, forest growth tended to stabilize within 30 years. Under high-density conditions, the model indicated a decline in the stand basal area from the onset of the simulation, suggesting that under these conditions, the forest has already reached its maximum-stock capacity. Conclusions: The model validation using independent data indicated close agreement between the observed and estimated values, suggesting the model is consistent in projecting species-group and stand growth. The methodology used in this study for developing the growth model should be tested in other species-rich forests.

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Section: Sub-models To Predict Forest Dynamicsmentioning

confidence: 96%

Predicting the dynamics of a native Araucaria forest using a distance-independent individual tree-growth model

et al. 2016

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“…Tree age should not be included as a predictor for growth in uneven-sized stands, due to large variances, both within stands Individual-tree distance-dependent growth models for uneven-sized Norway spruce (Peng 2000;Vanclay 2012) and within diameter-classes (Tarasiuk and Zwieniecki 1990). Instead, tree size is the most appropriate predictor of tree growth in structurally diverse stands (Shiue 1962;Zeide 1993;Pukkala et al 2009).…”

Section: Introductionmentioning

confidence: 99%

OUP accepted manuscript

2022

Forestry

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Individual tree selection (ITS) is one option to manage uneven-sized forest ecosystems. However, scientifically based field guidelines adapted to ITS and economic profitability are rare, often because there is a lack of suitable tree models to use in growth and treatment simulations. The objective of this study is to develop individual-tree distance-dependent growth models focusing on Norway spruce dominated uneven-sized stands. Three models of different complexity, but with the same structural basis, are presented, followed by some examples of growth patterns for the subject trees. The data include 1456 trees (307 sample trees) collected from five sites in southern Sweden. The basic model (S) depends on subject tree size as the predictor, the second model (SD) adds distance to competitors as a predictor, and the third model (SDC) adds crown ratio as a predictor to the structure. R2Adj increases with number of predictors from 0.48 to 0.58 to 0.62. The levels of RMSE improve accordingly from 5.02 cm2 year−1 (S) to 4.43 cm2 year−1 (SD) and 4.26 cm2 year−1 (SDC). The present calibration range and model structures primarily make the models suitable for management simulation of individual-tree selection of Norway spruce in southern Sweden. The format of the models allows for further extension with additional predictors and calibration data with greater coverage.

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“…Matrix models, introduced by Leslie (1945) and modified by Lefkovitch (1965) by grouping organisms in terms of stage categories rather than age categories, have been applied to almost all the subject areas of forestry (Usher 1969, Caswell 2001, Vanclay 2012, Liang & Picard 2013. In forest management, matrix models have been applied, for example, to evaluate economic outcomes (Buongiorno & Michie 1980, Fortini et al 2015 and ecological impacts (Van Mantgem & Stephenson 2005, Zhou et al 2008, or to optimise silviculture in mixed uneven-aged forests to increase the recruitment of browse-sensitive tree species without intervening in the ungulate population (Ficko et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Dimensionless numbers for the net present value and the perpetual value of sustainable timber harvests from a monospecific uneven-aged forest

Torres¹,

Fullana²

2019

iForest

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Biogeosciences and Forestry Biogeosciences and Forestry Dimensionless numbers for the net present value and the perpetual value of sustainable timber harvests from a monospecific uneven-aged forest Ignacio López Torres (1) , Carmen Fullana Belda (2) This paper proposes a simple and direct method to provide reliable approximations of the net present value (NPV) and the perpetual value (PV) of sustainable timber harvests from a monospecific uneven-aged forest based on dimensionless numbers. In addition, two new dimensionless numbers ρNPV and ρPV are introduced. These use the NPV or PV derived from the sale of timber throughout a harvest cycle, plus the final stocking value (as numerator), and the fair value of standing timber under IAS 41 (as denominator). They can be interpreted as economic performance indicators for forest management, inspired by the return on assets accounting concept, showing how profitable the forest is, relative to its total value, with sustainability and stability criteria. Those approximations to the variables NPV, PV, ρNPV and ρPV, were obtained under conditions of stable equilibrium from a matrix model. In order to exemplify and test the results, the model used data from uneven-aged managed Pinus nigra stands, considering three levels of tree diameter growth, six levels of basal area and 33 levels of recruitment, creating a total of 594 planning scenarios. Furthermore, the study revealed the existence of strong linear correlations between those variables and a dimensionless number.

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Modelling Continuous Cover Forests

Cited by 7 publications

References 51 publications

Predicting the dynamics of a native Araucaria forest using a distance-independent individual tree-growth model

Predicting the dynamics of a native Araucaria forest using a distance-independent individual tree-growth model

OUP accepted manuscript

Dimensionless numbers for the net present value and the perpetual value of sustainable timber harvests from a monospecific uneven-aged forest

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