scholarly journals Assessing site form as an indicator of site quality in even-aged Pinus radiata D. Don stands in north-western Spain

2019 ◽  
Vol 76 (4) ◽  
Author(s):  
Juan Alberto Molina-Valero ◽  
Ulises Diéguez-Aranda ◽  
Juan Gabriel Álvarez-González ◽  
Fernando Castedo-Dorado ◽  
César Pérez-Cruzado
Keyword(s):  
Pinus Radiata ◽  
Goodness Of Fit ◽  
Model Fitting ◽  
Site Index ◽  
Site Quality ◽  
Stand Age ◽  
Fit Statistics ◽  
Dominant Height ◽  
Western Spain ◽  
North Western

Abstract Key message Site form and site index have shown similar precision for estimating site quality in even-agedPinus radiataD. Don stands in north-western Spain. Additionally, SF presents the advantage that it does not require stand age information and can therefore be used in a wider set of situations in the forestry practice. Context Estimation of site quality is essential for characterizing, monitoring and predicting forest resources. Site index (i.e. the dominant height of the stand at a reference age) is ordinarily used to estimate site quality; however, this index is only useful for even-aged stands of known age. By contrast, SF is age-independent as it uses the dominant height of the stand at a reference dominant diameter. Aims The aim of this study was to compare the performance of SF and SI for site quality estimation in even-aged P. radiata stands. Methods Dynamic equations derived with the Generalized Algebraic Difference Approach (GADA) from the Hossfeld IV base model were fitted to predict site quality with both SI and SF. SF predictions were compared with SI regarding variability within the same plot and consistency in site quality predictions, using the observed maximum mean annual volume increment (MAI) as a direct measure of site quality. Results Both approaches showed good performance in model fitting and provided similar goodness-of-fit statistics and variability in the predictions. However, SI performed slightly stronger when related to MAI. Conclusion SF performed adequately in estimating site quality for even-aged P. radiata stands, with results comparable to those obtained using traditional SI.

Whole Stand Yield and Density Equations for Fourteen Forest Types in Minnesota

1993 ◽  
Vol 10 (2) ◽  
pp. 75-85 ◽  
Author(s):  
David K. Walters ◽  
Alan R. Ek
Keyword(s):  
Goodness Of Fit ◽  
Basal Area ◽  
Nonlinear Least Squares ◽  
Analysis Data ◽  
Site Index ◽  
Stand Age ◽  
Parameter Estimates ◽  
Forest Types ◽  
Fit Statistics ◽  
Number Of Stems

Abstract Models that estimate per acre basal area, number of stems, quadratic mean diameter, volumes to specified top diameters, and biomass per acre by stand age and site index were developed and fitted to data for 14 forest types in Minnesota. The resulting equations were developed from linear and nonlinear least squares analyses using USDA Forest Service Forest Inventory and Analysis data. These equations are intended for projecting future forest characteristics including yield on a statewide basis assuming the continuation of the level of management inherent in the data. Parameter estimates and goodness-of-fit statistics are provided for each model. Also discussed are the implementation procedures, assumptions, consistency of estimates, estimates for mixed species stands, and other considerations in applications. North. J. Appl. For. 10(2): 75-85.

Modeling dominant height growth of radiata pine (Pinus radiata D. Don) plantations in north-western Spain

2005 ◽  
Vol 215 (1-3) ◽  
pp. 271-284 ◽  
Author(s):  
Ulises Diéguez-Aranda ◽  
Harold E. Burkhart ◽  
Roque Rodríguez-Soalleiro
Keyword(s):  
Pinus Radiata ◽  
Radiata Pine ◽  
Height Growth ◽  
Dominant Height ◽  
Western Spain ◽  
Dominant Height Growth ◽  
North Western

Suitability of two methods of evaluating site quality for sugar maple in central Ontario

2006 ◽  
Vol 82 (5) ◽  
pp. 733-744 ◽  
Author(s):  
Nicholas J Buda ◽  
Jian R Wang
Keyword(s):  
Sugar Maple ◽  
Quality Evaluation ◽  
Growth Models ◽  
Site Index ◽  
Height Growth ◽  
Site Quality ◽  
Dominant Height ◽  
Index Site ◽  
Species Mixture ◽  
Stand Conditions

Stem analyses data collected in central Ontario stands were used to develop site index (height and age) and site form (height and diameter) models and curves for sugar maple. The suitability of both methods for evaluating sugar maple site productivity was examined. Two different equation forms were evaluated for both site index and site form models. A common modification of Richard's (1959) equation was most suitable for predicting dominant height at index age (site index) and reference diameter (site form). Potential effects of species mixture on sugar maple site index were examined. We found no significant effects on sugar maple height growth and site index in mixed stand conditions common in the region when compared to pure stands. The potential of site form as an alternative to site index was investigated through correlation analyses with site index and other site variables known to influence sugar maple height growth. Site form was not related to site index, nor any site variables related to sugar maple height growth. It is therefore inadequate for evaluating sugar maple site quality. We recommend height growth models and site index curves developed in this study be used to replace those from other regions currently used in central Ontario. Key words: site index, site form, sugar maple, site quality evaluation, mixedwood, uneven-aged

scholarly journals Influences of Forest Type, Stand Age, and Weather on Deer Weights and Antler Size in the Southern Appalachians

1997 ◽  
Vol 21 (1) ◽  
pp. 11-18 ◽  
Author(s):  
William M. Ford ◽  
A. Sydney Johnson ◽  
Philip E. Hale ◽  
James M. Wentworth
Keyword(s):  
Age Structure ◽  
Forest Type ◽  
Site Index ◽  
Forest Stand ◽  
Site Quality ◽  
Stand Age ◽  
Southern Appalachians ◽  
Study Region ◽  
Pinus Spp ◽  
Percent Area

Abstract We analyzed correlations of forest type, age structure, and site index data with weights and antler characteristics of yearling white-tailed deer (Odocoileus virginianus) bucks from specific localities in the Chattahoochee, Cherokee, Nantahala, and Pisgah national forests in Georgia, Tennessee, and North Carolina. Areas in the northern part of the study region produced larger deer with larger antlers than those in the southern portion of the region. These northern areas differed from those to the south in having more diverse ownership and land use and in origins of deer stock. Weights and antler characteristics were significantly correlated (P < 0.05) with percent area in the cove hardwood type, but otherwise were poorly correlated with forest stand type and site index. Percent area in young (0-8 yr old) cove hardwood and in mid-successional (9-20 and 21-40) cove hardwood, pine (Pinus spp.), and upland oak (Quercus spp.) were significantly correlated (P < 0.05) with deer variables, particularly in years following a poor mast crop. Much of the quantifiable habitat influences on deer in the Southern Appalachians probably is masked by low deer densities and the small site quality differences among areas examined. Because much of the forest consists of mature mast-producing oaks and abundant forage is produced in both mature and younger aged stands, deer numbers seem to be below any threshold of quantifiable effects due to forest stand age structure. South. J. Appl. For. 21(1):11-18.

Assessing the effect of measurement error in age on dominant height and site index estimates

2011 ◽  
Vol 41 (8) ◽  
pp. 1698-1709 ◽  
Author(s):  
Chengcai Ni ◽  
Gordon Nigh
Keyword(s):  
Measurement Error ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Site Index ◽  
Stand Age ◽  
Initial Value ◽  
Dominant Height ◽  
Projection Length ◽  
Age Model ◽  
Projection Error

Stand age is often hard to measure accurately. Measurement error in age affects height estimates when height is projected from one age to another age. In this study, our objective was to derive an estimator for the variance of the component of projection error associated with the error in age. To evaluate the estimator, a simulation approach was employed and the results showed that the estimator worked well in most cases. When the variance of the error in age increases and the projection is forward, however, the estimator might not work as well as in other cases. Another objective was to examine how the error in age behaved under different height–age models and to what extent it affected height and site index estimates. The effect of the error in age depended on its magnitude, the height–age model, initial value of dominant height and age, and projection length. It was also shown that the effect was sometimes negligible, but it could be considerable in other cases. Data from 80 ponderosa pine ( Pinus ponderosa Dougl. ex Laws.) trees in British Columbia, Canada, were used in an illustrative example.

A calibrateable site index model for Pinus kesiya plantations in southeastern Africa

2002 ◽  
Vol 32 (11) ◽  
pp. 1916-1928 ◽  
Author(s):  
Kalle Eerikäinen ◽  
Danaza Mabvurira ◽  
Ladislaus Nshubemuki ◽  
Jussi Saramäki
Keyword(s):  
Random Parameter ◽  
Site Index ◽  
Stand Age ◽  
Random Parameters ◽  
Index Model ◽  
Forest Inventories ◽  
Pinus Kesiya ◽  
Dominant Height ◽  
Random Parameter Model ◽  
Site Index Model

The aim of the study was to develop a site index model for Pinus kesiya Royle ex Gordon plantations in southeastern Africa based on the relationship between the dominant height and stand age. Conversely, analysis of dominant height and age data showed that the growth patterns of plantations were different. In addition, the asymptotes and forms of standwise dominant height curves varied within plantations. In developing a common site index model, instead of using the more common approach of estimating separate dominant height–age models for different plantations or sites, a mean curve approach based on a linear random parameter model with fixed and random parameters was applied. The random parameter model of this study was calibrated by predicting random parameters for the plantation and stand effects, in accordance with the standard linear prediction theory. The analyses showed that the calibration of the dominant height model was an efficient method to obtain reliable dominant height predictions of a stand, particularly when several dominant height–age observations from different stands of a plantation and at least one measured dominant height and stand age of a target stand are available. This is the case in many forest inventories based on temporary samples, i.e., cross-sectional data. The new site index model is a useful tool for use in different mensurational applications, and its properties can efficiently be utilized for example in forest inventories of P. kesiya plantations in southeastern Africa.

Dominant-height and site-index equations for ponderosa pine in east-central Arizona

1991 ◽  
Vol 21 (5) ◽  
pp. 606-611 ◽  
Author(s):  
W. F. Stansfield ◽  
J. P. McTague ◽  
R. Lacapa
Keyword(s):  
Ponderosa Pine ◽  
Habitat Type ◽  
Prediction Method ◽  
Site Index ◽  
Site Quality ◽  
Predictive Capability ◽  
East Central ◽  
Dominant Height ◽  
Central Arizona ◽  
Parameter Prediction

A dominant-height equation for ponderosa pine (Pinusponderosa Laws.) was constructed utilizing a parameter prediction method and a model by J.E. King. The site-index equation was obtained by inverting the dominant-height equation. A method was examined for indirectly obtaining parameter prediction equations. It proved superior to two direct parameter prediction approaches. Other site-quality variables, such as habitat type groups and elevation, were included in the dominant-height and site-index equations and were successful in refining predictive capability.

scholarly journals A comparison between traditional ordinary least-squares regression and three methods for enforcing additivity in biomass equations using a sample of Pinus radiata trees

2020 ◽  
Vol 50 ◽  
Author(s):  
Mohan KC ◽  
Euan G. Mason ◽  
Horacio E. Bown ◽  
Grace Jones
Keyword(s):  
Least Squares ◽  
Pinus Radiata ◽  
Goodness Of Fit ◽  
Ordinary Least Squares ◽  
Total Biomass ◽  
Least Squares Regression ◽  
Above Ground Biomass ◽  
Fit Statistics ◽  
Biomass Equations ◽  
Power Transformations

Background: Additivity has long been recognised as a desirable property of systems of equations to predict the biomass of components and the whole tree. However, most tree biomass studies report biomass equations fitted using traditional ordinary least-squares regression. Therefore, we aimed to develop models to estimate components, subtotals and above-ground total biomass for a Pinus radiata D.Don biomass dataset using traditional linear and nonlinear ordinary leastsquares regressions, and to contrast these equations with the additive procedures of biomass estimation.Methods: A total of 24 ten-year-old trees were felled to assess above-ground biomass. Two broad procedures were implemented for biomass modelling: (a) independent; and (b) additive. For the independent procedure, traditional linear models (LINOLS) with scaled power transformations and y-intercepts and nonlinear power models (NLINOLS) without y-intercepts were compared. The best linear (transformed) models from the independent procedure were further tested in three different additive structures (LINADD1, LINADD2, and LINADD3). All models were evaluated using goodness-of-fit statistics, standard errors of estimates, and residual plots.Results: The LINOLS with scaled power transformations and y-intercepts performed better for all components, subtotals and total above-ground biomass in contrast to NLINOLS that lacked y-intercepts. The additive model (LINADD3) in a joint generalised linear least-squares regression, also called seemingly unrelated regression (SUR), provided the best goodness-of-fit statistics and residual plots for four out of six components (stem, branch, new foliage and old foliage), two out of three subtotals (foliage and crown), and above-ground total biomass compared to other methods. However, bark, cone and bole biomass were better predicted by the LINOLS method.Conclusions: SUR was the best method to predict biomass for the 24-tree dataset because it provided the best goodness-of-fit statistics with unbiased estimates for 7 out of 10 biomass components. This study may assist silviculturists and forest managers to overcome one of the main problems when using biomass equations fitted independently for each tree component, which is that the sum of the biomasses of the predicted tree components does not necessarily add to the total biomass, as the additive biomass models do.

scholarly journals Modeling dominant height growth using permanent plot data for Pinus brutia stands in the Eastern Mediterranean region

2021 ◽  
Vol 30 (1) ◽  
pp. eSC03
Author(s):  
Tammam Suliman ◽  
Uta Berger ◽  
Marieke Van der Maaten-Theunissen ◽  
Ernst Van der Maaten ◽  
Wael Ali
Keyword(s):  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Site Index ◽  
Permanent Plots ◽  
Stand Age ◽  
Pinus Brutia ◽  
Dominant Height ◽  
Algebraic Difference ◽  
Generalized Algebraic Difference Approach

Aim of the study: At current, forest management in the Eastern Mediterranean region is largely based on experience rather than on management plans. To support the development of such plans, this study develops and compares site index equations for pure even-aged Pinus brutia stands in Syria using base-age invariant techniques that realistically describe dominant height growth.Materials and methods: Data on top height and stand age were obtained in 2008 and 2016 from 80 permanent plots capturing the whole range of variation in site conditions, stand age and stand density. Both the Algebraic Difference Approach (ADA) and the Generalized Algebraic Difference Approach (GADA) were used to fit eight generalized algebraic difference equations in order to identify the one which describes the data best. For this, 61 permanent plots were used for model calibration and 19 plots for validation.Main results: According to both biological plausibility and model accuracy, the so-called Sloboda equation based on the GADA approach showed the best performance.Research highlights: The study provides a solid classification and comparison of Pinus brutia stands growing in the Eastern Mediterranean region and can thus be used to support sustainable forest management planning.Keywords: site index; Generalized Algebraic Difference Approach (GADA); Sloboda equation.

Sign in / Sign up

Export Citation Format

Share Document