Top height definition and its effect on site index determination in thinned and unthinned loblolly pine plantations

Sharma, Mahadev; Amateis, Ralph L.; Burkhart, Harold E.

doi:10.1016/s0378-1127(01)00737-x

Cited by 85 publications

(69 citation statements)

References 5 publications

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“…1 -Th e f or esTr y Ch r on iCl e 25 criticism as it is applied in mixed-species, uneven-aged stands (Monserud 1984b, Monserud 1988, Pokharel and Froese 2009. The concept of using the site tree is the central strength of site index, but the ambiguity associated with its selection and measurement has been widely criticized in the published literature (Monserud 1984b, Monserud 1988, The Technical Advisory Committee 1998, Sharma et al 2002, Mailly et al 2004, Pokharel and Froese 2009. Several ambiguities introduce bias into determining the site index of a particular stand.…”

Section: The Phytocentric Approachmentioning

confidence: 99%

“…Several ambiguities introduce bias into determining the site index of a particular stand. Sources of bias that can be introduced include substantial variation in the number and selection criteria of site trees used to estimate top height between organizations and regions (Sharma et al 2002), sampling error variation due to differences in the plot size and site tree location (e.g., site trees in a plot vs. site trees selected adjacent to the plot; Hägglund 1981), and polymorphism in height growth curves that introduces errors in extrapolating the height at a reference age (Jones 1969).…”

Section: The Phytocentric Approachmentioning

confidence: 99%

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An ecological land classification approach to modeling the production of forest biomass

Pokharel¹,

Dech²

2011

The Forestry Chronicle

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Forest site classification is a prerequisite to successful integrated forest resources planning and management. Traditionally, site classification has emphasized a phytocentric approach, with tools such as the site index having a rich and long history in forest site evaluation. The concept of site index was primarily devised to assess site productivity of an even-aged, single-species stand. Site index has been the primary method of forest site evaluation in support of management for traditional forest products. However, this method of site classification has been criticized as the needs, perspectives and social values of the public regarding forest management have changed the emphasis from timber production to multiplevalue forestry practices. There are alternative approaches to forest site classification that have the potential to meet the growing demands placed on forest information for inventory and modeling purposes. Ecological Land Classification (ELC), is a phytogeocentric approach that stratifies the landscape into ecologically meaningful units (ecosites) based on substrate characteristics, moisture regime and canopy composition. This approach offers a more holistic view of site productivity evaluation; however, until recently it has been difficult to acquire data to support widespread mapping of ecosites. Remote sensing technology along with predictive modeling and interpretive mapping techniques make the application of an ecosite-based approach at the forest landscape level possible. As forest management moves towards the consideration of a broader set of resources (e.g., woody biomass), there is an opportunity to develop new tools for linking forest productivity to the sustainable production of forest bioproducts with forest ecosites as a solid foundation for segmenting the landscape.Key words: forest site classification, site index, site productivity, Ecological Land Classification (ELC), ecosites, forest biomass, bioproducts RÉSUMÉLa classification des sites forestiers est un pré-requis au succès de la planification et de l'aménagement des ressources forestières. Habituellement, la classification des sites a mise en évidence une approche phytocentrique, comptant sur des outils comme l'indice de qualité de la station qui affiche un historique riche et durable de l' évaluation des sites forestiers. Le concept d'indice de la qualité de station a été établi principalement pour évaluer la productivité de la station dans le cas d'un peuplement équienne composé d'une seule espèce. L'indice de la qualité de station a été la principale méthode d' éva-luation d'un site forestier utilisée dans le cas de l'aménagement pour les produits forestiers traditionnels. Cependant, cette méthode de classification du site a fait l' objet de critiques compte tenu que les besoins, les perspectives et les valeurs sociales du public relativement à l'aménagement forestier ont réorienté l'accent mis sur la production de bois vers des pratiques forestières considérant les multiples valeurs du milieu. Il existe des approch...

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Section: The Phytocentric Approachmentioning

confidence: 99%

Section: The Phytocentric Approachmentioning

confidence: 99%

An ecological land classification approach to modeling the production of forest biomass

Pokharel¹,

Dech²

2011

The Forestry Chronicle

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“…Therefore, stand top height was calculated as the arithmetic mean of the four tallest trees according to the 100 tallest trees per hectare, and the selection of the tallest trees did not take into account the species to circumvent the limitation [55] that site index models are difficult to apply in mixed stands, where height estimates of dominant trees must be available for each species in a stand [56]. Stand mean height was determined using Lorey mean height [2,9]. Summary statistics of these two stand variables are presented in Table 1.…”

Section: Stand Top and Stand Mean Height Relationshipmentioning

confidence: 99%

“…Estimating site productivity is crucial to predict forest growth and yield, as well as to maintain sustainable management of forest resources [2,3]. Site index, which is commonly defined as the mean height of dominant and codominant trees of a stand (hereafter referred to as stand top height) at a pre-specified age [4][5][6], has been accepted and widely used as the most expedient indicator of forest site productivity in Germany and North America since around the end of the 19th century because of its simple calculation and efficacious prediction [3,6,7].…”

Section: Introductionmentioning

confidence: 99%

Spatial Autoregressive Models for Stand Top and Stand Mean Height Relationship in Mixed Quercus mongolica Broadleaved Natural Stands of Northeast China

Lou

Zhang

Lei

et al. 2016

Forests

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Abstract:The relationship of stand top and stand mean height is important for forest growth and yield modeling, but it has not been explored for natural mixed forests. Observations of stand top and stand mean height can present spatial dependence or autocorrelation, which should be considered in modeling. Simultaneous autoregressive (SAR) models, including spatial lag model (SLM), spatial Durbin model (SDM) and spatial error model (SEM), within nine spatial weight matrices were utilized to model the stand top and stand mean height relationship in the mixed Quercus mongolica Fisch. ex Ledeb. broadleaved natural stands of Northeast China, using ordinary least squares (OLS) as a benchmark model. The results showed that there was a high linear relationship between stand top and stand mean height and that there was a positive spatial autocorrelation pattern in model residuals of OLS. Moreover, SEM and SDM performed better than OLS in terms of reducing the spatial dependence of model residuals and model fitting, regardless of which spatial weight matrix was used. SEM was better than SDM. SLM scarcely reduced the spatial autocorrelation of model residuals. Among nine spatial matrices in SEM, rook contiguous matrix performed best in model fitting, followed by inverse distances raised to the second power (1/d 2 ) and local statistics model matrix (LSM).

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“…the tallest or largest diameter, free-growing, uninjured trees in a sample plot (Carmean 1975, Monserud 1984, Carmean and Lenthall 1989, Nigh and Love 1999. As a consequence, H d is generally defined as the height of the largestdiameter tree on a 0.01-ha plot, providing the tree is suitable (e.g., Forest Productivity Council of British Columbia 1998, Sharma et al 2002). For a 0.04-ha plot, this represents the height of 4 top-height trees based on the largest-diameter trees.…”

Section: Introductionmentioning

confidence: 99%

Ratio estimation to improve estimates of top height from suboptimal samples in forest inventory plots in Québec

Mailly¹,

Gaudreault²,

Blais³

2009

The Forestry Chronicle

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Top height is one of the most useful variables provided by sample plot measurements conducted during forest inventory programs. Combined with tree age, it allows the determination of site index, a common measure of forest site productivity. Unfortunately, there are cases where the number of site trees is suboptimal; this potential problem can lead to imprecise estimates of top height and site index. We approached this problem using ratio estimation techniques and incomplete data sets from forest inventory plots in Québec. We tested different combinations of suboptimal sampling of site trees to estimate top height based on their diameters, using only 2 or 3 site trees per 0.04-ha plot, instead of 4. The results show that suboptimal sampling of site trees should not be conducted randomly, and that some combinations consistently performed better than others. Also, some combinations never outperformed others and should be avoided when estimating top height of some important tree species in Québec using suboptimal sampling of site trees. Finally, for the best combinations, we concluded that the ratio estimation technique generally provided precise and unbiased estimates of top height.Key words: top height, site index, site trees, ratio estimation, forest inventory RÉSUMÉ La hauteur dominante est une des variables les plus utiles découlant de l' échantillonnage de placettes d'inventaire forestier. Lorsqu' elle est combinée à l'âge de l'arbre, elle permet de déterminer l'indice de qualité de station (IQS), lequel représente une mesure pratique de la productivité d'une station. Malheureusement, il y a des cas où le nombre d'arbres échantillons prévus à cet effet est sous-optimal et ce problème potentiel peut engendrer des estimations imprécises de la hauteur dominante et de l'IQS. Nous avons abordé ce problème en utilisant la technique de l' estimateur ratio combinée à des données incomplètes de placettes d'inventaire forestier du Québec. Nous avons testé différentes combinaisons sous-optimales d'arbres-échantillons afin d' estimer la hauteur dominante sur la base des plus gros diamètres à hauteur de poitrine, en utilisant seulement deux ou trois arbres par placette de 0,04 hectare au lieu de quatre. Les résultats montrent qu'un échantil-lonnage sous-optimal ne devrait pas être réalisé au hasard et que certaines combinaisons d'arbres donnent des estimations de la hauteur dominante plus précises que d'autres. De plus, certaines combinaisons sous-optimales ont systématiquement mal estimé la hauteur dominante des placettes et ne devraient donc jamais être utilisées à cet effet. Enfin, nous concluons que la méthode d' estimation de la hauteur dominante à l'aide de l' estimateur ratio s' est avérée généralement précise et non biaisée pour les meilleures combinaisons d'arbres échantillons en mode d' échantillonnage sous-optimal.Mots clés : hauteur dominante; indice de qualité de station; arbres indicateurs de la station; estimateur ratio; inventaire forestier 1 Direction de la recherche forestière, Ministère des Resso...

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Top height definition and its effect on site index determination in thinned and unthinned loblolly pine plantations

Cited by 85 publications

References 5 publications

An ecological land classification approach to modeling the production of forest biomass

An ecological land classification approach to modeling the production of forest biomass

Spatial Autoregressive Models for Stand Top and Stand Mean Height Relationship in Mixed Quercus mongolica Broadleaved Natural Stands of Northeast China

Ratio estimation to improve estimates of top height from suboptimal samples in forest inventory plots in Québec

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