Knowledge of ecological characteristics of trees, sites and tree growth on different sites is fundamental for silvicultural decision-making and planning. With the biogeoclimatic ecosystem classification in place, silvicultural management in British Columbia has been given an ecological foundation; however, relationships between growth and site have not yet been fully investigated. The purpose of this study was to determine how height growth of Douglas-fir within the drier portion of the CWH zone varies with site. We adopted site index (m @ 50 yr bh) as a species-specific measure of forest productivity, recognizing that it indicates height growth performance at a selected point in time. If forest productivity is correlated with ecological measures of site quality, what site factors should be used to quantify the relationships? Because of compensating effects, the numerous site factors can be reduced to four primary (synoptic) factors that directly affect plant establishment and growth: climate (light and temperature), soil moisture, soil nutrients, and soil aeration (not used in this study).

Knowledge of ecological site characteristics and tree growth on different sites is fundamental for silvicultural decisionmaking and planning. With biogeoclimatic ecosystem classification in place in British Columbia, silvicultural management has been given an ecological foundation; however, relationships between growth and site quality have not yet been fully investigated. The purpose of this study was to determine how site conditions within the SBS zone affect the height growth of lodgepole pine (Pl) and interior spruce (Sx).

Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in coastal forests of B.C. Its range extends from sea-level to almost timberline, and from the hypermaritime region on the west coast of Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. With this relatively wide climatic amplitude, a large variability in the height growth pattern of Pacific silver fir can be expected, since climate is considered to be the most influential determinant of the trajectory of height over age of forest trees. This variability, however, is not reflected in the height growth curves and site index tables used to estimate Pacific silver fir site index, since the curves and tables were developed from low-elevation stands on Vancouver Island. Consequently, when these curves and tables are applied to high-elevation or submaritime stands, we get biased estimates of site index. Accurate estimates of site index are necessary for accurate yield predictions. Furthermore, they are essential for making rational decisions about whether to cut the forest in situations where potential tree growth is marginal, such as in high-elevation forests.

Accurate and reliable predictions of site index (height of dominant trees at a reference age, usually 50 years at breast-height) for timber crop species is essential for silvicultural site-specific decision making. Site index can be predicted from site quality once the relationship between site index and site quality has been quantified. Site quality is defined as the sum of all environmental factors affecting the biotic community, such as the factors directly influencing the growth of vascular plants (light, heat, soil moisture, soil nutrients, and soil aeration). Since these factors vary greatly in time, indirect estimates of site quality have widely been used as predictors for site index in various multiple regression models. Trembling aspen (Populus tremuloides Michx.) is the most widely distributed broadleaf species in British Columbia, especially in the Boreal White and Black Spruce (BWBS) biogeoclimatic zone. Growing this species for sustainable timber production requires a good understanding of its productivity attributes and accurate predictions of its growth. This extension note presents (1) relationships between trembling aspen site index and some indirect measures of site quality, and (2) site index prediction models using the indirect measures of site quality as predictors.

Height growth models of coastal low- and mid-elevation Pacific silver fir, low-elevation white spruce, and low- and midelevation lodgepole pine have been used for predicting productivity of subalpine fir, Engelmann spruce, and lodgepole pine, respectively. These models, however, are biased in predicting height growth of high-elevation subalpine fir, Engelmann spruce, and lodgepole pine. To improve this situation, 329 sample plots (165 for subalpine fir, 90 for Engelmann spruce, and 74 for lodgepole pine) were located throughout the Engelmann Spruce-Subalpine Fir (ESSF) zone. Stem analysis was carried out on three dominant trees in each 0.04 ha sample plot. For each study species, a height growth model was developed on the data from two-thirds of the sample plots using the conditioned Chapman-Richards’ function; the model was validated using the remaining one-third of the sample plots.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2005. / The aim of this study was to develop a set of models that will allow the determination of volume for Tectona grandis trees and stands grown in plantation form in Tanzania. As a secondary objective, models describing tree and dominant stand height were developed. Total volume and volume ratio models were fitted that respectively predict total tree volume and merchantable volume. In order to allow the calculation of volume for different product classes and dimensions, taper models were fitted. All the data were collected by non-destructive sampling methods using a Barr and Stroud optical dendrometer. This proved to be an accurate and inexpensive method of collecting data for developing volume and taper models. Sampling stratification was based on age and site quality and as wide a range as possible was covered to ensure adequate representation of all growing sites and ages present in Tanzanian teak plantations. A total of 2617 individual observations were made from 222 trees at three teak plantations. Several models were selected from the literature to describe teak volume and shape. Results indicated that the Schumacher and Hall (1933) volume equation best describes total volume over and underbark to a fixed upper limit of 7.5 cm. Merchantable volume to upper stem diameter and height limits were best described by respectively the Burkhart (1977) volume ratio model and the Cao and Burkhart (1980) modification thereof. Many of the fitted taper models were unable to adequately describe stem shape over the whole stem, mainly due to the large range in tree sizes and ages used in model fitting. The variable form taper model by Perez, Burkhart and Stiff (1990) provided the best results according to various criteria and is recommended for predicting teak underbark diameters to various heights and, if only a single model is required, the merchantable volume. Top height growth of teak stands was adequately described by the generalized Schumacher (1939) model with the value of the exponent k estimated from the sample data. From this a series of anamorphic site index curves were developed. Suitable height-dbh curves were obtained by a simple linear model and predictions improved by including stand age and site index as predictor variables.

Submitted by Milena Rubi ( ri.bso@ufscar.br) on 2017-11-07T17:07:00Z No. of bitstreams: 1 SANTOS_Carlos_2017.pdf: 906783 bytes, checksum: bccefa4afd7b8ef5d98df40bff297122 (MD5) / Approved for entry into archive by Milena Rubi ( ri.bso@ufscar.br) on 2017-11-07T17:07:12Z (GMT) No. of bitstreams: 1 SANTOS_Carlos_2017.pdf: 906783 bytes, checksum: bccefa4afd7b8ef5d98df40bff297122 (MD5) / Approved for entry into archive by Milena Rubi ( ri.bso@ufscar.br) on 2017-11-07T17:07:22Z (GMT) No. of bitstreams: 1 SANTOS_Carlos_2017.pdf: 906783 bytes, checksum: bccefa4afd7b8ef5d98df40bff297122 (MD5) / Made available in DSpace on 2017-11-07T17:07:31Z (GMT). No. of bitstreams: 1 SANTOS_Carlos_2017.pdf: 906783 bytes, checksum: bccefa4afd7b8ef5d98df40bff297122 (MD5) Previous issue date: 2017-05-09 / Não recebi financiamento / The productive capacity is conventionally estimated by anamorphic or polymorphic calculated site curves; however, these curves have some limitations. Due to these limitations, the objective of this work was to evaluate the creation of growth curves for site classification by the nonlinear quantile regression method and to compare them with the curves generated by the algebraic difference method. The database was collected in two mesoregions of the state of São Paulo (Paulista and Bauru Metropolitan Macro), with 460 measurements in 98 plots with distinct periods in Eucalyptus sp. The site curves were adjusted according to the Chapman-Richards model using the algebraic difference method for anamorphic and polymorphic curves and nonlinear quantum regression (RNLQ). The results of this work allowed to conclude that the site curves adjusted by the RNLQ method are superior to the curves generated by the algebraic difference method by graphical analysis of the residuals with smaller ranged of the errors and greater homogeneity and residual standard error with lower values in the classes in general. / A capacidade produtiva é estimada convencionalmente por meio de curvas de sítio calculadas de forma anamórfica ou polimórfica, contudo, estas curvas possuem algumas limitações. Devido a estas limitações, o objetivo deste trabalho foi avaliar a criação de curvas de crescimento para classificação de sítio pelo método de regressão não linear quantílica e compará-las com as curvas geradas pelo método da diferença algébrica. A ba se de dados foi coletada em duas mesorregiões do estado de São Paulo (Macro Metropolitana Paulista e Bauru), com 460 medições em 98 parcelas com períodos distintos em Eucalyptus sp. As curvas de sítio foram ajustadas segundo modelo de Chapman-Richards pelo método da diferença algébrica para curvas anamórficas e polimórficas e regressão não linear quantílica (RNLQ). Os resultados deste trabalho permitiram concluir que as curvas de sítio ajustadas pelo método da RNLQ são superiores às curvas geradas pelo método da diferença algébrica pela análise gráfica dos resíduos com menor amplitude dos erros e maior homogeneidade e erro padrão residual com menores valores nas classes em geral.

The main objective of this dissertation is to build site index curves relating dominant height and age and to elaborate density management diagram (DMD) for individuals of Hovenia dulcis located in the central area of the state of Rio Grande do Sul, Brazil. To do that, it was used information from 4 stands, aged 25, located at Fundação de Pesquisa Agropecuária (FEPAGRO) and from a population of free trees, with DAPs varying from 5 to 45 cm, located at the campus of Universidade Federal de Santa Maria (UFSM), both in the municipal district of Santa Maria. For the construction of the sites indexes, information from 18 dominant trees was gathered in the 4 stands located at FEPAGRO, observing the methodology for trunk analysis. In places where trees were under competition, data for the elaboration of the density management diagrams were collected in trees of dominant, intermediate and dominated strata, considering the method of the punctual density. In the place where trees were free from competition, census was made. As a result, in the elaboration of the site index curves, the Backman model was selected, being verified the necessity of construction of two groups of index curves, from 5 to 25 years-old, with interval of 2 meters and index of 25. For the Site I-A, 3 index curves were created from 22 to 24 meters and, for the join of the Sites I-B+II+III, 6 index curves from 8 to 18 meters were produced. It was also possible to conclude that the Reineke model adjusted itself to calculate the closing density lines of the dossal and of the self-thinning, with angular coefficients very close to -1.5, for both of them, being demonstrated that the potency law of -3/2 of self-thinning was taken into account and that it was very similar to the hypothesis postulated by Reineke. The population density, for the beginning of the total capacity of the dossal, was of 42.5% of the maximum number of trees that the place allows, and that, with the collected data, it was possible to build diagrams for the density management, from the 5 to the 31 cm of diameter of the tree of medium basal area. / O objetivo principal deste trabalho é construir curvas de índice de sítio relacionando altura dominante e idade e elaborar diagramas de manejo de densidade (DMD), para populações de Hovenia dulcis localizadas na região central do estado do Rio Grande do Sul, Brasil. Para tanto, foram utilizadas informações de 4 povoamentos, com idades de 25 anos, localizado na Fundação de Pesquisa Agropecuária (FEPAGRO), e de uma população de árvores livres, com DAPs variando de 5 a 45 cm, localizado no campus da Universidade Federal de Santa Maria (UFSM), ambos no município de Santa Maria. Para a construção dos índices de sítios, coletaram-se informações de 18 árvores dominantes, nos 4 povoamentos localizados na FEPAGRO, observando a metodologia para análise de tronco. Nos locais onde as árvores estavam sob concorrência, os dados para a elaboração dos diagramas de manejo da densidade, foram coletados em árvores dos estratos dominante, intermediário e dominado, pelo método da densidade pontual. No local onde as árvores estavam livres de concorrência, realizou-se censo. Como resultado, na elaboração das curvas índice de sítio, o modelo de Backman foi o selecionado, ficando constatada a necessidade da construção de dois conjuntos de curvas índices, da idade de 5 a 25 anos, com intervalo de 2 metros e idade índice de 25 anos. Para o sítio I-A, foram geradas 3 curvas índice, de 22 a 24 metros e, para a união dos Sítios I-B+II+III, 6 curvas índices de 8 a 18 metros. Também foi possível concluir que o modelo de Reineke ajustou-se satisfatoriamente para estimar as linhas de densidade de fechamento do dossel e de autodesbaste, com coeficientes angular se aproximando muito de -1,5, para ambas, ficando demonstrado que a lei da potência de -3/2 de autodesbaste foi contemplada e que se aproximou muito da hipótese postulada por Reineke. A densidade populacional, para o início da total lotação do dossel, foi de 42,5% do número máximo de árvores que o local permite, sendo que com os dados coletados foi possível construir diagramas para o manejo da densidade, dos 5 aos 31 cm de diâmetro da árvore de área basal média.

Trembling aspen (Populus tremuloides Michx.) is one of the most common tree species in the boreal and temperate forests of North America. It grows on many different sites and associates with a variety of tree species. In BC, aspen is frequent throughout all submontane and montane continental forested zones. Relationships between environmental factors and forest productivity have been the subjects of many studies. Most of these studies, using various topographic, soil, physical and chemical properties as independent variables, had limited success in accounting for the variation in SI over a large geographic area. The objectives of this study were (1) to quantify relationships between aspen SI and environmental factors at two spatial scales, and (2) to develop predictive SI models from easily measurable environmental factors.

Thesis (MScFor)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Site Index is used extensively in modern commercial forestry both as an indicator of current and future site potential, but also as a means of site comparison. The concept is deeply embedded into current forest planning processes, and without it empirical growth and yield modelling would not function in its present form. Most commercial forestry companies in South Africa currently spend hundreds of thousands of Rand annually collecting growth stock data via inventory, but spend little or no money on the default compartment data (specifically Site Index) which is used to estimate over 90% of the product volumes in their long term plans. A need exists to construct reliable methods to determine Site Index for sites which have not been physically measured (the socalled "default", or indirect Site Index). Most previous attempts to model Site Index have used multiple linear regression as the model, alternative methods have been explored in this thesis: Regression tree analysis, random forest analysis, hybrid or model trees, multiple linear regression, and multiple linear regression using regression trees to identify the variables. Regression tree analysis proves to be ideally suited to this type of data, and a generic model with only three site variables was able to capture 49.44 % of the variation in Site Index. Further localisation of the model could prove to be commercially useful. One of the key assumptions associated with Site Index, that it is unaffected by initial planting density, was tested using linear mixed effects modelling. The results show that there may well be role played by initial stocking in some species (notably E. dunnii and E. nitens), and that further work may be warranted. It was also shown that early measurement of dominant height results in poor estimates of Site Index, which will have a direct impact on inventory policies and on data to be included in Site Index modelling studies. This thesis is divided into six chapters: Chapter 1 contains a description of the concept of Site Index and it's origins, as well as, how the concept is used within the current forest planning processes. Chapter 2 contains an analysis on the influence of initial planted density on the estimate of Site Index. Chapter 3 explores the question of whether the age at which dominant height is measured has any effect on the quality of Site Index estimates. Chapter 4 looks at various modelling methodologies and compares the resultant models. Chapter 5 contains conclusions and recommendations for further study, and finally Chapter 6 discusses how any new Site Index model will effect the current planning protocol. / AFRIKAANSE OPSOMMING: Hedendaagse kommersiële bosbou gebruik groeiplek indeks (Site Index) as 'n aanduiding van huidige en toekomstige groeiplek moontlikhede, asook 'n metode om groeiplekke te vergelyk. Hierdie beginsel is diep gewortel in bestaande beplanningsprosesse en daarsonder kan empiriese groeien opbrengsmodelle nie in hul huidige vorm funksioneer nie. SuidAfrikaanse bosboumaatskappye bestee jaarliks groot bedrae geld aan die versameling van groeivoorraad data deur middel van opnames, maar weinig of geen geld word aangewend vir die insameling van ongemete vak data (veral groeiplek indeks) nie. Ongemete vak data word gebuik om meer as 90% van die produksie volume te beraam in langtermyn beplaning. 'n Behoefte bestaan om betroubare metodes te ontwikkel om groeiplek indeks te bereken vir groeiplekke wat nog nie opgemeet is nie. Die meeste vorige pogings om groeiplek indeks te beraam het meervoudige linêre regressie as model gebruik. Alternatiewe metodes is ondersoek; naamlik regressieboom analise, ewekansige woud analise, hibriedeof modelbome, meervoudige linêre regressie en meervoudige linêre regressie waarin die veranderlike faktore bepaal is deur regressiebome. Regressieboom analise blyk geskik te wees vir hierdie tipe data en 'n veralgemeende model met slegs drie groeiplek veranderlikes dek 49.44 % van die variasie in groeiplek indeks. Verdere lokalisering van die model kan dus van kommersiële waarde wees. 'n Sleutel aanname is gemaak dat aanvanklike plantdigtheid nie 'n invloed op groeiplek indeks het nie. Hierdie aanname is getoets deur linêre gemengde uitwerkings modelle. Die toetsuitslag dui op 'n moontlikheid dat plantdigtheid wel 'n invloed het op sommige spesies (vernaamlik E. dunnii en E. nitens) en verdere navorsing kan daarom geregverdig word. Dit is ook bewys dat metings van jonger bome vir dominante hoogtes gee aanleiding tot swak beramings van groeiplek indekse. Gevolglik sal hierdie toestsuitslag groeivoorraad opname beleid, asook die data wat vir groeiplek indeks modellering gebruik word, beïnvloed. Hierdie tesis word in ses hoofstukke onderverdeel. Hoofstuk een bevat 'n beskrywing van die beginsel van groeiplek indeks, die oorsprong daarvan, asook hoe die beginsel tans in huidige bosbou beplannings prosesse toegepas word. Hoofstuk twee bestaan uit ń ontleding van die invloed van aanvanklike plantdigtheid op die beraming van groeplek indeks. In hoofstuk drie word ondersoek wat die moontlike invloed is van die ouderdom waarop metings vir dominante hoogte geneem word, op die kwaliteit van groeplek indeks beramings het. Hoofstuk vier verken verskeie modelle metodologieë en vergelyk die uitslaggewende modelle. Hoofstuk vyf bevat gevolgtrekkings en voorstelle vir verdere studies. Afsluitend, is hoofstuk ses ń bespreking van hoe enige nuwe groeiplek indeks modelle die huidige beplannings protokol kan beïnvloed.