Compatible crown ratio and crown height models

Dyer, M.; Burkhart, Harold E.

doi:10.1139/x87-096

Cited by 51 publications

(25 citation statements)

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“…The response of crown length to competition can be utilised to improve growth models on an individual tree basis [35]. Most of the growth models which incorporate crown length variables were established in the Western US with conifer species [3,6,7,23,35,36,41,43]. In Europe recently Pretzsch [27] and Hasenauer [14] have established growth prediction models with crown parameters as predictor variables.…”

Section: Discussionmentioning

confidence: 99%

Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) ? technique, establishment of sample methods and application in forest growth analysis

Spathelf¹

2003

Ann. For. Sci.

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-A technique to date branch mortality was used to estimate crown recession of Norway spruce and Silver fir in uneven-aged mixed forests on temporary plots of the Black Forest (Germany). In a preliminary study accurate and efficient sampling methods were developed. Results of the main study indicate that unthinned trees show a high crown recession rate, contrarily to thinned trees, which reveal more balanced crowns. Height increment and Hegyi's competition index were the only significant variables left in the final regression model. Trees of equal competition status but with higher height increment exhibit higher crown recession rates. This tendency is even more pronounced with Norway spruce than with Silver fir. Norway spruce, however, shows a higher crown recession rate with increasing competition compared with Silver fir of similar height increment. This seems to indicate a lower shade tolerance of Norway spruce.Norway spruce / Silver fir / crown length / crown recession / branch mortality Résumé -Évolution en hauteur des houppiers d'épicéa (Picea abies (L.) Karst.) et de sapin pectiné (Abies alba Mill.) -technique, mise en oeuvre de méthodes d'échantillonnage, application à l'analyse de la croissance des forêts. On a utilisé une technique permettant de dater la mortalité des branches pour estimer la régression par le bas des houppiers de l'épicéa et du sapin pectiné, dans des placettes temporaires installées dans des forêts mélangées et inéquiennes de la Forêt Noire (Allemagne). Les résultats démontrent qu'en l'absence d'éclaircie les arbres présentent un taux de régression des houppiers plus élevé, au contraire des arbres ayant bénéficié d'éclaircies dont les houppiers apparaissent mieux équilibrés. L'accroissement en hauteur et l'indice de compétition de Hegyi sont les seules variables significatives qui subsistent dans le modèle de régression final. Les arbres soumis à un niveau de compétition équivalent, mais dont l'accroissement en hauteur est plus élevé, présentent un taux de régression du houppier plus important. Cette tendance est même plus prononcée pour l'épicéa que pour le sapin pectiné. Lorsque le niveau de compétition s'accroît, l'épicéa accuse un taux de réduction plus élevé que le sapin pectiné à accroissement en hauteur équivalent. Ceci semble indiquer une moindre tolérance à l'ombre de l'épicéa. épicéa / sapin pectiné / hauteur de houppier / régression par le bas du houppier / mortalité des branches

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Section: Discussionmentioning

confidence: 99%

Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) ? technique, establishment of sample methods and application in forest growth analysis

Spathelf¹

2003

Ann. For. Sci.

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“…Crown dimension modeling is highly dependent on the accuracy of total height and height to the live crown base data and/or equations. Predictions of tree crown ratio have been based on allometric relations between stand and tree variables [1,5,6,7,25,26]. Crown ratio can be predicted directly from tree and/or stand variables [e.g.…”

Section: Introductionmentioning

confidence: 99%

A tree crown ratio prediction equation for eucalypt plantations

Soares¹,

Tomé²

2001

Ann. For. Sci.

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-Based on a data set from spacing trials and permanent plots of Eucalyptus globulus Labill., several nonlinear equations for crown ratio prediction (based on exponential, logistic, Richards and Weibull functions) were tested. The total data set was used to fit and select the equations. The equations were evaluated in terms of measures of fit and prediction ability: adjusted-R 2 , residual mean square, sum of PRESS residuals and sum of absolute PRESS residuals. The normality of the studentized residuals was analyzed using normal QQ plots. The presence of heteroscedasticity associated with the error term was checked by plotting the studentized residuals against the predicted values. The significance of the estimated parameters was verified. Model error was characterized in terms of bias and precision. The Richards function was selected. This equation is age and density dependent, reflecting the importance of intertree competition; an initial tree dimension and a measure of stand productivity were also required as explanatory variables.

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“…In general, the average live-crown ratio of a stand declines linearly or nearly so with competition. This relationship has been shown for various coniferous and hardwood species [37][38][39][40]. Zhao et al [41] presented a model for predicting the average live-crown ratio for loblolly pine with relative spacing, which is another term for Wilson's percent of height [42], i.e., average spacing between trees divided by average height of the dominant trees.…”

Section: Height To the Base Of The Live Crownmentioning

confidence: 99%

“…The prediction error associated with these models can result in crown lengths longer than the tree is tall at low levels of competition and negative values of crown length when the stand is self-thinning. Dyer and Burkhart [38] simultaneously fit regression models for the live-crown ratio and crown length with seemingly unrelated regression (c.f. [43]) in an attempt to avoid this problem.…”

Section: Height To the Base Of The Live Crownmentioning

confidence: 99%

Neighbor and Height Effects on Crown Properties Associated with the Uniform-Stress Principle of Stem Formation

Dean

2018

Forests

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According to the uniform-stress principle of stem formation, the amount of leaf area a tree carries and the leverage it exerts on the stem determine the stem dimensions. Within an even-aged monoculture, the leaf area per tree and the leverage placed on the stem are functions of tree density and tree height. The uniform-stress principle presents the means to translate density effects on crown characteristics into stem dimensions and total standing volume. This approach is truly a top-down method of simulating growth tree and stand growth because leaf area and other crown properties must be determined before stem size and taper can be calculated. Each crown property influences either the sail area or the leverage placed on the stem, but the degree to which a specific crown property affects these parameters changes with stand density and height. Leverage is the more complicated of the two variables, being a function of the height to the base of the live crown and the vertical distribution of leaf area. The purpose of this brief review is to summarize the effects of stand density on the height to the base of the live tree and the vertical distribution of leaf area and the various ways these variables have been quantified.

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Compatible crown ratio and crown height models

Cited by 51 publications

References 0 publications

Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) ? technique, establishment of sample methods and application in forest growth analysis

Reconstruction of crown length of Norway spruce (Picea abies (L.) Karst.) and Silver fir (Abies alba Mill.) ? technique, establishment of sample methods and application in forest growth analysis

A tree crown ratio prediction equation for eucalypt plantations

Neighbor and Height Effects on Crown Properties Associated with the Uniform-Stress Principle of Stem Formation

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