Evaluating and modelling genus and species variation in height-to-diameter relationships for Tropical Hill Forests in Peninsular Malaysia

Lam, Tzeng Yih; Kershaw, John A.; Hajar, Z. S. Nur; Rahman, K. Abd; Weiskittel, Aaron R.; Potts, Matthew D.

doi:10.1093/forestry/cpw051

Cited by 11 publications

(11 citation statements)

References 30 publications

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“…However, measuring upper stem diameters requires additional time and effort in the field, which may not be a feasible option in many cases. Lam et al [24] proposed adding the taxonomic hierarchy of genus and species as random effects in developing species-specific, height-diameter relationship models for tropical forests in Malaysia. However, the trajectories of stem profile are usually more complicated than H-D relationships.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Data Grouping Strategies on Prediction Accuracy of Tree-Stem Taper for Six Common Species in the Southeastern US

Yang

Green

2022

Forests

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Clustering data into similar characteristic groups is a commonly-used strategy in model development. However, the impact of data grouping strategies on modeling stem taper has not been well quantified. The objective of this study was to compare the prediction accuracy of different data grouping strategies. Specifically, a population-level model was compared to the models fitted with grouped data based on taxonomic rank, tree form and size. A total of 3678 trees were used in the analyses, which included six common species in upland hardwood forests of the southeastern U.S. Results showed that overall predictions are more accurate when building stem taper models at the species, species group or division level rather than at the population level. The prediction accuracy was not considerably improved between species-specific functions and models fitted with species-related groups for the four hardwood species examined. Grouping data by taxonomic rank provided more reliable predictions than height-to-diameter ratio (H–D ratio) or diameter at breast height (DBH). The form/size-related grouping methods (i.e., data grouped by H–D ratio or DBH) generally did not improve the prediction precision compared to a population-level model. In this study, the effect of sample size in model fitting showed a minimal impact on prediction accuracy. The methodology presented in this study provides a modeling strategy for mixed-species data, which will be of practical importance when data grouping is needed for developing stem taper models.

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Section: Discussionmentioning

confidence: 99%

Comparison of Data Grouping Strategies on Prediction Accuracy of Tree-Stem Taper for Six Common Species in the Southeastern US

Yang

Green

2022

Forests

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“…The major challenge in our study is that a large number of tree species existed with relatively few observations for the majority [69]. The task of developing a species-specific height-diameter model for several species seems intractable, at least initially, and the mixed species approach used is advantageous when the species is treated as a random effect to circumvent the need for grouping the data [70]. However, we did not consider this because of computational complexity, but species-specific effects on the height-diameter relationships were included using the dummy variable modelling approach.…”

Section: Tree Height-diameter Model and Description Of The Managementmentioning

confidence: 99%

Defining Deforestation Patterns Using Satellite Images from 2000 and 2017: Assessment of Forest Management in Miombo Forests—A Case Study of Huambo Province in Angola

et al. 2018

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A few studies have recently been published on changes in land use/land cover (LU/LC) of Angolan Miombo forests, however, none have attempted to offer forest management solutions for degraded Miombo forests. Landscapes are witness to past and present natural and social processes influencing the environment, where each period in the past leaves footprints on the landscape's development, which can be described by a continual decrease in forest area over time. The expansion of degraded areas from 2000 to 20017 began near urban areas where many Miombo forests have been eliminated or highly degraded, particularly in the southwest and northeast of the Huambo province. Large areas of degraded forests were observed along the Benguela railway (Caminho de ferro de Benguela). Our detailed analysis of the landcover map suggests that the impact has been devastating and there is no form of forest protection, which leads to unregulated exploitation. Descriptions of the Miombo forest dynamics are explained using height-diameter curves developed for different vegetation types that provide important insights about forest structures in the management zones. The height-diameter models differed for all vegetation types, and four management zones (MZ) were created based on a set of particular attributes. The vegetation types differed in each management zone, which included agricultural land and bare soil (MZ-E), grassland or savanna (MZ-C), open Miombo forests (MZ-B), and closed Miombo forests (Miombo forests). The four management zones were easily identified on the available maps and the height-diameter models developed represent a fundamental tool for future studies on forest planning.Sustainability 2019, 11, 98 2 of 20 agreed definition of forest degradation which makes the discussion more complex [3]. Deforestation is considered the result of the clearing of land for agriculture [4], both for the large-scale production of global commodities [5,6] and, in Africa, for small-scale production of food and cash crops [7]. Deforestation is among the most commonly studied phenomena in the frontier literature, as it is often associated with negative impacts on the global climate and biodiversity [6,8]. The scale of the environmental legacy of deforestation is dependent on both the magnitude and timing of historic land cover changes, not merely the snapshot of forest cover that is directly observable today [9][10][11][12][13][14]. The most important anthropogenic alterations of natural environments have always been the clearing of forests to establish cropland and pasture, and the exploitation of forests for fuelwood and construction materials. Analysing landscape changes due to past and present natural and social processes at different scales over time constitutes the departure point for landscape management because of close links between forests and physical attributes of the landscape. The mix of LC and LU (landscape composition) usually includes agricultural lands and native vegetation, and human dwellings in villages and urban areas. Th...

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“…Additionally, few studies have considered how site effects act together to shape H-D allometric relationship for a species. Lam et al, (2017) and Kershaw et al, (2008) used the flexibility of the mixed-effect modelling strategy to derive species-specific parameter estimates from multispecies datasets. Such modelling approaches are rare or not yet developed in the tropical Africa.…”

Section: Introductionmentioning

confidence: 99%

Height-diameter allometric equations of an emergent tree species from the Congo Basin

Kafuti

Bulcke

Beeckman

et al. 2022

Forest Ecology and Management

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Evaluating and modelling genus and species variation in height-to-diameter relationships for Tropical Hill Forests in Peninsular Malaysia

Cited by 11 publications

References 30 publications

Comparison of Data Grouping Strategies on Prediction Accuracy of Tree-Stem Taper for Six Common Species in the Southeastern US

Comparison of Data Grouping Strategies on Prediction Accuracy of Tree-Stem Taper for Six Common Species in the Southeastern US

Defining Deforestation Patterns Using Satellite Images from 2000 and 2017: Assessment of Forest Management in Miombo Forests—A Case Study of Huambo Province in Angola

Height-diameter allometric equations of an emergent tree species from the Congo Basin

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