Puude konkurentsi- ja struktuuriindeksite analüüs arukase (Betula pendula Roth) puistute modelleerimise eesmärgil

A Thesis for applying for the degree of Doctor of Philosophy in ForestryThe thesis is designed to establish and assess different approaches of competition measurement, incorporated with various competitor selection methods, focusing on silver birch in Estonia. The effect of competition and some other tree and stand variables on the growth and the mortality of trees are explored. Moreover, stands are characterized employing several structural indices calculated for sample plots of different shapes and sizes. The findings indicate that the measures including the trees spatial information, have superiority over the measures ignoring the trees locations within a forest stand, when studying the dynamics of stands and their effects on the structure and functioning of forest ecosystems. Also, plots with different shapes showed almost equal estimation accuracy, thus circular plots are preferred due to their smaller ratio of perimeter to surface. Besides, the optimum plot size depends on the stand structure, with an attempt to keep sample plots as small as possible to reduce the assessment efforts and costs.Doktoritöö eesmärgiks on uurida erinevaid meetodeid puudevahelise konkurentsi hindamiseks ja konkurentpuude kindlakstegemiseks eelkõige Eestis kogutud arukase puistute andmetele tuginedes. Põhjalikumalt uuriti puudevahelise konkurentsi ning puude ja puistu takseertunnuste seoseid puude kasvu ja suremusega. Lisaks kirjeldati puistute seisundit mitmete struktuuriindeksite abil erineva suuruse ja kujuga proovialasid kasutades. Töö tulemused näitavad, et puistute dünaamika uurimisel on puude ruumilist paiknemist arvestavatel tunnustel eeliseid võrreldes tunnustega, mis ei arvesta puude ruumilist paiknemist. Erineva kujuga proovialad andsid takseertunnuste hinnangu küll sarnase täpsusega, kuid ringikujulisi proovialasid tuleks eelistada nende ümbermõõdu-pindala väiksema suhtarvu tõttu. Optimaalne prooviala suurus sõltub puistu struktuurist, kuid proovialad tuleks siiski valida võimalikult väiksena, et vähendada mõõtmistele kuluvat aega ja vahendeid.Publication of this dissertation is supported by the Estonian University of Life Sciences and by the Doctoral School of Earth Sciences and Ecology created under the auspices of the European Social Fund

Modelling Post-Disturbance Successional Dynamics of the Canadian Boreal Mixedwoods

Natural disturbances, such as fire and insect outbreaks, play important roles in natural forest dynamics, which are characterized over long time scales by changes in stand composition and structure. Individual-based forest simulators could help explain and predict the response of forest ecosystems to different disturbances, silvicultural treatments, or environmental stressors. This study evaluated the ability of the SORTIE-ND simulator to reproduce post-disturbance dynamics of the boreal mixedwoods of eastern Canada. In 1991 and 2009, we sampled all trees (including seedlings and saplings) in 431 (256 m2) plots located in the Lake Duparquet Research and Teaching Forest (western Quebec). These plots were distributed in stands originating from seven wildfires that occurred between 1760 and 1944, and which represented a chronosequence of post-disturbance stand development. We used the 1991 inventory data to parameterize the model, and simulated short-to long-term natural dynamics of post-fire stands in both the absence and presence of a spruce budworm outbreak. We compared short-term simulated stand composition and structure with those observed in 2009 using a chronosequence approach. The model successfully generated the composition and structure of empirical observations. In long-term simulations, species dominance of old-growth forests was not accurately estimated, due to possible differences in stand compositions following wildfires and to differences in stand disturbance histories. Mid-to long-term simulations showed that the secondary disturbance incurred by spruce budworm did not cause substantial changes in early successional stages while setting back the successional dynamics of middle-aged stands and accelerating the dominance of white cedar in late-successional post-fire stands. We conclude that constructing a model with appropriate information regarding stand composition and disturbance history considerably increases the strength and accuracy of the model to reproduce the natural dynamics of post-disturbance boreal mixedwoods

Stand-level growth models for long-term projections of the main species groups in Norway

Stand-level growth and yield models are important tools that support forest managers and policymakers. We used recent data from the Norwegian National Forest Inventory to develop stand-level models, with components for dominant height, survival (number of survived trees), ingrowth (number of recruited trees), basal area, and total volume, that can predict long-term stand dynamics (i.e. 150 years) for the main species in Norway, namely Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and birch (Betula pubescens Ehrh. and Betula pendula Roth). The data used represent the structurally heterogeneous forests found throughout Norway with a wide range of ages, tree size mixtures, and management intensities. This represents an important alternative to the use of dedicated and closely monitored long-term experiments established in single species even-aged forests for the purpose of building these stand-level models. Model examination by means of various fit statistics indicated that the models were unbiased, performed well within the data range and extrapolated to biologically plausible patterns. The proposed models have great potential to form the foundation for more sophisticated models, in which the influence of other factors such as natural disturbances, stand structure including species mixtures, and management practices can be included.publishedVersio

A stand-level growth and yield model for thinned and unthinned even-aged Scots pine forests in Norway

Management of Scots pine (Pinus sylvestris L.) in Norway requires a forest growth and yield model suitable for describing stand dynamics of even-aged forests under contemporary climatic conditions with and without the effects of silvicultural thinning. A system of equations forming such a stand-level growth and yield model fitted to long-term experimental data is presented here. The growth and yield model consists of component equations for (i) dominant height, (ii) stem density (number of stems per hectare), (iii) total basal area, (iv) and total stem volume fitted simultaneously using seemingly unrelated regression. The component equations for stem density, basal area, and volume include a thinning modifier to forecast stand dynamics in thinned stands. It was shown that thinning significantly increased basal area and volume growth while reducing competition related mortality. No significant effect of thinning was found on dominant height. Model examination by means of various fit statistics indicated no obvious bias and improvement in prediction accuracy in comparison to existing models in general. An application of the developed stand-level model comparing different management scenarios exhibited plausible long-term behavior and we propose this is therefore suitable for national deployment.publishedVersio

Synthesis of Small Organic Molecule Based on Malononitrile Group toward Green Energy Performance in Organic Photovoltaic Solar Cells

In this study, a small organic compound containing cyano and N,N-dimethyl aniline as acceptor and donor groups, respectively linked through the conjugate system, were synthesized. Then, its structure was confirmed by FT-IR spectroscopy. Next, in order to investigate the photovoltaic properties of these organic molecules, it was tested in the fabrication of organic photovoltaic solar cells (OPVSCs). The organic solar cell with FTO/TiO2/dye molecules/electrolyte/Pt electrode configuration was constructed

Tamm Review: Individual-based forest management or Seeing the trees for the forest

In the last century, local or individual-based forest management was introduced by various forest scientists including Scha spacing diaeresis delin, Abetz and Pollanschutz as an alternative to traditional global thinning methods. They suggested breaking large forest stands down into smaller neighbourhood-based units. The centre of each of these neighbourhood-based units is a frame tree (also referred to as final crop tree, elite tree or target tree) with clearly defined properties that depend on the management objectives. In each management intervention, trees in the neighbourhood of frame trees that in the next 5-10 years are likely to influence the frame trees negatively are removed selectively. In contrast to global methods, management is only carried out where there are frame trees. Local or individual-based forest management methods were first introduced in a commercial forestry context, but rather constitute generic methods that can be efficiently applied in management for conservation, carbon sequestration and recreation. They are also often applied in the context of continuous cover forestry (CCF). In this study, we analysed the behaviour of test persons selecting frame trees in 26 training sites, so-called marteloscopes, from all over Great Britain. Although the test persons were new to individual-based management, statistical performance indicators suggested that frame trees were selected in accordance with the theory of local or individual-based forest management. Unexpectedly the test persons even achieved a comparatively high degree of agreement. This result contrasts the low agreement and partly unsatisfying performance indicators incurred in the selection of frame-tree competitors, the second step of local forest management. The outcomes of this study highlight that training in individual-based forest management needs to put more emphasis on the identification of frame-tree competitors

Analysis of Individual Tree Competition on Diameter Growth of Silver Birch in Estonia

Aim of study: The present study evaluates a set of competition indices including spatially explicit indices combined with different competitor selection approaches and non-spatially explicit competition indices. The aim was to quantify and describe the neighbouring effects on the tree diameter growth of silver birch trees.Area of study: Region throughout Estonia. Material and methods: Data from the Estonian Network of Forest Research Plots was used. After quantifying the selected indices, the best non-spatial indices and spatial indices (combined with neighbour selection methods) were separately devised into a growth model as a predictor variable to assess the ability of the diameter growth model before and after adding competition measures. To test the species-specific effect on the competition level, the superior indices were recalculated using Ellenberg’s light indicators and incorporated into the diameter growth model. Main results: Statistical analyses showed that the diameter growth is a function of neighbourhood interactions and spatial indices were better growth predictors than non-spatial indices. In addition, the best selections of competitive neighbours were acquired based on the influence zone and the competition elimination angle concepts, and using Ellenberg’s light values had no significant improvement in quantifying the competition effects. Research highlights: Although the best ranking spatial competition measures were superior to the best non-spatial indices, the differences were negligible.Keywords: Competition indices; zone of influence; stem diameter increment; Betula pendula Roth.ERRATUM PDF

Analysis of Individual Tree Competition Effect on Diameter Growth of Silver Birch in Estonia

Aim of study: The present study evaluates a set of competition indices including spatially explicit indices combined with different competitor selection approaches and non-spatially explicit competition indices. The aim was to quantify and describe the neighbouring effects on the tree diameter growth of silver birch trees. Area of study: Region throughout Estonia. Material and methods: Data from the Estonian Network of Forest Research Plots was used. After quantifying the selected indices, the best non-spatial indices and spatial indices (combined with neighbour selection methods) were separately devised into a growth model as a predictor variable to assess the ability of the diameter growth model before and after adding competition measures. To test the species-specific effect on the competition level, the superior indices were recalculated using Ellenberg’s light indicators and incorporated into the diameter growth model. Main results: Statistical analyses showed that the diameter growth is a function of neighbourhood interactions and spatial indices were better growth predictors than non-spatial indices. In addition, the best selections of competitive neighbours were acquired based on the influence zone and the competition elimination angle concepts, and using Ellenberg’s light values had no significant improvement in quantifying the competition effects. Research highlights: Although the best ranking spatial competition measures were superior to the best non-spatial indices, the differences were negligible

Influence of dyeing conditions of natural dye extracted from Berberis integerrima fruit on color shade of woolen yarn

A new source of natural dye was introduced to obtain different colors on woolen yarn by varying the dyeing condition and formulation recipe. The fruit extract of Berberis integerrima was used as a natural dye for coloration of wool fibers. Response surface methodology (RSM) has been applied to design experimental runs to evaluate the interactive effects of the operating variables. The concentration of natural dye, concentration of mordant, pH of dye bath, and dyeing time at boiling temperature was selected as independent parameters. The effect of these parameters was examined on color shade (Hue angle) of dyed yarn samples as a dependent factor. The results were indicated that the different hue angles and color shades were achieved at proposed dyeing condition of wool fibers with B. integerrima which was in the range of 25° up to 282°. Extracted natural dye from B. integerrima was presented an inhibition zone at all applied concentrations and it was dependent on its concentration

A stand-level growth and yield model for thinned and unthinned even-aged Scots pine forests in Norway

Management of Scots pine (Pinus sylvestris L.) in Norway requires a forest growth and yield model suitable for describing stand dynamics of even-aged forests under contemporary climatic conditions with and without the effects of silvicultural thinning. A system of equations forming such a stand-level growth and yield model fitted to long-term experimental data is presented here. The growth and yield model consists of component equations for (i) dominant height, (ii) stem density (number of stems per hectare), (iii) total basal area, (iv) and total stem volume fitted simultaneously using seemingly unrelated regression. The component equations for stem density, basal area, and volume include a thinning modifier to forecast stand dynamics in thinned stands. It was shown that thinning significantly increased basal area and volume growth while reducing competition related mortality. No significant effect of thinning was found on dominant height. Model examination by means of various fit statistics indicated no obvious bias and improvement in prediction accuracy in comparison to existing models in general. An application of the developed stand-level model comparing different management scenarios exhibited plausible long-term behavior and we propose this is therefore suitable for national deployment