Humans have affected the Swedish forests for a long time, mainly through agriculture and forestry. Since the beginning of the 20th century, a lot of changes have taken place in forest policy, which have affected the structures of our forests, such as tree age, size and species distributions. By using information from different types of historical data, we can increase our understanding of the earlier structures of forests and how to manage them in the future. This study investigated changes in annual growth and changes in age, diameter, height and tree species distribution in the forests of Östergötland from year 1927 to the period 1983-2017, using data from the Swedish National Forest Inventory. Six tree species where used, Picea spp, Pinus spp, Quercus robur, Betula spp, Alnus spp and Populus tremula. There was an increase in the proportion of Picea spp, and a decrease in the proportion of Pinus spp since 1927. The proportion of deciduous trees also increased but not as much. Interestingly, the proportion of Betula spp had fallen since 1927, but the now larger proportion of young trees indicate that the proportion of Betula spp is increasing again. Q. robur, P. tremula, Picea spp and Pinus spp also had a larger proportion of younger trees in the more recent period. There was a significantly higher proportion of tall trees during the latter period for all tree species. For growth rate in width, the results varied among tree species. For Betula spp it had decreased and for Q. robur it had increased. For the coniferous trees there was hardly any difference between the periods. Overall, the results show that Östergötland's forests have been influenced by forestry and increased ungulate populations since the first inventory 1927 and that there have been changes in the composition of the forests. / Människan har länge påverkat de svenska skogarna. Sedan 1900-talets början har en hel del förändringar skett inom skogspolitiken, vilket har påverkat bland annat skogarnas ålder- och storleksfördelning, samt trädslagsfördelning. Genom att använda information från olika typer av historiska data kan vi öka vår förståelse om hur skogar såg ut förr och vad som har påverkat dem. Denna studie undersökte skillnader i tillväxt, höjd-och diameterfördelning, samt åldersfördelning i Östergötlands skogar från år 1927 till perioden 1983–2017, med hjälp av data från riksskogstaxeringen. Sex trädslag användes; gran (Picea spp), tall (Pinus spp), ek (Quercus robur), björk (Betula spp), al (Alnus spp) och asp (Populus tremula). En kraftig ökning av andelen gran hade skett sedan 1927, medan andelen tall hade minskat. För lövträden hade det endast skett en liten ökning i andel. Intressant var också att andelen björk hade minskat sedan 1927 och att andelen björkar yngre än 50 år var större den senare perioden, vilket indikerar att björkens andel kan vara på väg att öka igen. Ek, asp, gran och tall hade också en större andel yngre träd under den senare perioden. För alla trädslag fanns det en betydligt mindre andel höga träd år 1927. För årlig tillväxt i bredd varierade resultaten trädslagen emellan. För björk hade årsringsbredden minskat sedan 1927, medan den hade ökat för ek. För barrträden var det knappt någon skillnad mellan perioderna. Resultaten visar att Östergötlands skogar har påverkats mycket av skogsbruket, samt klövviltsbete, sedan 1927 och att det har skett flera strukturella förändringar i skogarnas sammansättning.

Time-since-fire data are used to describe wildfire disturbances, the major disturbance type in the Boreal forest, over a landscape. These data can be used to calculate various parameters about wildfire disturbances, such as size, shape and severity. Collecting time-since-fire data is expensive and time consuming; the ability to derive it from existing forest inventory data would result in availability of fire data over larger areas. The objective of this thesis was to explore the use of forest inventory information for the prediction of time-since-fire data in the mixedwood boreal forests of Saskatchewan. Regression models were used to predict time-since-fire from forest inventory variables for each inventory polygon with a stand age. Non-water polygons with no stand age value were assigned values from neighbouring polygons, after splitting long polygons that potentially crossed many historic fire boundaries. This procedure filled gaps that prevented polygons from being grouped together in latter analysis. The predicted time-since-fire ages were used to generate wildfire parameters such as age-class distributions and fire cycle. Three methods were examined to group forest inventory polygons together to predict fire event polygons: simple partitions, hierarchical clustering, and spatially constrained clustering. The predicted fire event polygons were used to generate polygon size distribution wildfire metrics. I found that there was a relationship between time-since-fire and forest inventory variables at this study site, although the relationship was not strong. As expected, the strongest relationship was between the age of trees in a stand as indicated by the inventory and the time-since-fire. This relationship was moderately improved by including tree species composition, harvest modification value, and the ages of the surrounding polygons. Assigning no-age polygons neighbouring values and grouping the forest inventory polygons improved the predicted time-since-fire results when compared spatially to the observed time-since-fire data. However, a satisfactory method of comparing polygon shapes was not found, and the map outputs were highly dependent on the grouping method and parameters used. Overall it was found that forest inventory data did not have sufficient detail and accuracy to be used to derive high quality time-since-fire information.

LiDAR (Light Detection and Ranging) directly measures canopy vertical structures, and provides an effective remote sensing solution to accurate and spatiallyexplicit mapping of forest characteristics, such as canopy height and Leaf Area Index. However, many factors, such as large data volume and high costs for data acquisition, precludes the operational and practical use of most currently available LiDARs for frequent and large-scale mapping. At the same time, a growing need is arising for realtime remote sensing platforms, e.g., to provide timely information for urgent applications. This study aims to develop an airborne profiling LiDAR system, featured with on-the-fly data processing, for near real- or real- time forest inventory. The development of such a system involves implementing the on-board data processing and analysis as well as building useful regression-based models to relate LiDAR measurements with forest biophysical parameters. This work established a paradigm for an on-the-fly airborne profiling LiDAR system to inventory regional forest resources in real- or near real- time. The system was developed based on an existing portable airborne laser system (PALS) that has been previously assembled at NASA by Dr. Ross Nelson. Key issues in automating PALS as an on-the-fly system were addressed, including the design of an archetype for the system workflow, the development of efficient and robust algorithms for automatic data processing and analysis, the development of effective regression models to predict forest biophysical parameters from LiDAR measurements, and the implementation of an integrated software package to incorporate all the above development. This work exploited the untouched potential of airborne laser profilers for realtime forest inventory, and therefore, documented an initial step toward developing airborne-laser-based, on-the-fly, real-time, forest inventory systems. Results from this work demonstrated the utility and effectiveness of airborne scanning or profiling laser systems for remotely measuring various forest structural attributes at a range of scales, i.e., from individual tree, plot, stand and up to regional levels. The system not only provides a regional assessment tool, one that can be used to repeatedly, remotely measure hundreds or thousands of square kilometers with little/no analyst interaction or interpretation, but also serves as a paradigm for future efforts in building more advanced airborne laser systems such as real-time laser scanners.

Background: The objective of this study was to verify the effect that plot locational errors, termed plot co-registration errors, have on the strength of regression between LiDAR canopy metrics and the measured total standing volume (TSV) of plots in a Pinus radiata forest. Methods: A 737 hectare plantation of mature Pinus radiata located in Northern Hawkes Bay was selected for the study. This forest had been measured in a pre-harvest inventory and had aerial LiDAR assessment. The location of plots was verified using a survey-grade GPS. Least square linear regression models were developed to predict TSV from LiDAR canopy metrics for a sample of 204 plots. The regression strength, accuracy and bias was compared for models developed using either the actual (verified) or the incorrect (intended) locations for these plots. The change to the LiDAR canopy metrics after the plot co-registration errors was also established. Results: The plot co-registration error in the sample ranged from 0.7 m to 70.3 m, with an average linear spatial error of 10.6 m. The plot co-registration errors substantially reduced the strength of regression between LiDAR canopy metrics and TSV, as the model developed from the actual plot locations had an R2 of 44%, while the model developed from the incorrect plot locations had an R2 of 19%. The greatest reductions in model strength occurred when there was less than a 60% overlap between the plots defined by correct and incorrect locations. Higher plot co-registration errors also caused significant changes to the height and density LiDAR canopy metrics that were used in the regression models. The lower percentile elevation LiDAR metrics were more sensitive to plot co- registration errors, compared to higher percentile metrics. Conclusion: Plot co-registration errors have a significant effect on the strength of regressions formed between TSV and LiDAR canopy metrics. This indicates that accurate measurements of plot locations are necessary to fully utilise LiDAR for inventory purposes in forests of Pinus radiata.

The deficiencies of traditional dendrometry mean improvements in methods of tree mensuration are necessary in order to obtain accurate tree metrics for applications such as resource appraisal, and biophysical and ecological modelling. This thesis tests the potential of SfM-MVS (Structure-fromMotion with Multi-View Stereo-photogrammetry) using the software package PhotoScan Professional, for accurately determining linear (2D) and volumetric (3D) tree metrics. SfM is a remote sensing technique, in which the 3D position of objects is calculated from a series of photographs, resulting in a 3D point cloud model. Unlike other photogrammetric techniques, SfM requires no control points or camera calibration. The MVS component of model reconstruction generates a mesh surface based on the structure of the SfM point cloud. The study was divided into two research components, for which two different groups of study trees were used: 1) 30 small, potted ‘nursery’ trees (mean height 2.98 m), for which exact measurements could be made and field settings could be modified, and; 2) 35 mature ‘landscape’ trees (mean height 8.6 m) located in parks and reserves in urban areas around the South Island, New Zealand, for which field settings could not be modified. The first component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which 2D (height, crown spread, crown depth, stem diameter) and 3D (volume) tree metrics could be estimated. Each of the 30 nursery trees was photographed and measured with traditional dendrometry to obtain ground truth values with which to evaluate against SfM-MVS estimates. The trees were destructively sampled by way of xylometry, in order to obtain true volume values. The RMSE for SfM-MVS estimates of linear tree metrics ranged between 2.6% and 20.7%, and between 12.3% and 47.5% for volumetric tree metrics. Tree stems were reconstructed very well though slender stems and branches were reconstructed poorly. The second component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which height and DBH could be estimated. Each of the 35 landscape trees, which varied in height and species, were photographed, and ground truth values were obtained to evaluate against SfM-MVS estimates. As well as this, each photoset was thinned to find the minimum number of images required to achieve total image alignment in PhotoScan and produce an SfM point cloud (minimum photoset), from which 2D metrics could be estimated. The height and DBH were estimated by SfM-MVS from the complete photosets with RMSE of 6.2% and 5.6% respectively. The height and DBH were estimated from the minimum photosets with RMSE of 9.3% and 7.4% respectively. The minimum number of images required to achieve total alignment was between 20 and 50. There does not appear to be a correlation between the minimum number of images required for alignment and the error in the estimates of height or DBH (R2 =0.001 and 0.09 respectively). Tree height does not appear to affect the minimum number of images required for image alignment (R 2 =0.08).

Subject of research: : Kaišiadorys state forest enterprise, Žiežmariai district, central part of Strošiūnai forest. Goals of the research: Using Strošiūnai forest 1904, 1947, 1977, 1987 and 2002 years forest inventory data describe forest settlement, forest inventory works, changes in forest resources and possible reasons for that. Methodology: comparative analysis using data grouping, comparing data, indicators specialization, average values and percentages calculation and generalization methods. Research results: Strošiūnai forest, like separate economic unit was created in 1871 during forest inventory works carried out at Bačkonys (55,5 ha), Žasliai (225,4 ha) forests and Strošiūnai forest (804,2 ha), total 1085,2 ha.In years 1871-1904 total area increased by 37,9 ha, woodlands - 46,4 ha (0,8%), areas covered by forests 62,1 ha (2,5%), decreased areas without forest 15,6 ha (1,7%), agriculutural land 0,4 ha and land not used 8,2 ha (0,8%). Total forest area in years 1947-2002 decreased by 25,6 ha, forestland 2,7 ha, woodlands increased by 24%. Not a forestland area decreased by - 22,9ha (1,7%). Area of land dedicated for technological use increased by 21ha (1,6%), agricultural land decreased by 13 ha (1%). In years 1871-1904 pinewoods decreased from 92,7% to 89,8%, birch woodlands stayed the same, spruce forestland increased - from 3,4% to 7,7%. In years 1947-2002 pinewoods decreased almost a half from 82,1% to 46,0%. Areas with spruce increased almost three times (2... [to full text]

Time-since-fire data are used to describe wildfire disturbances, the major disturbance type in the Boreal forest, over a landscape. These data can be used to calculate various parameters about wildfire disturbances, such as size, shape and severity. Collecting time-since-fire data is expensive and time consuming; the ability to derive it from existing forest inventory data would result in availability of fire data over larger areas. The objective of this thesis was to explore the use of forest inventory information for the prediction of time-since-fire data in the mixedwood boreal forests of Saskatchewan. Regression models were used to predict time-since-fire from forest inventory variables for each inventory polygon with a stand age. Non-water polygons with no stand age value were assigned values from neighbouring polygons, after splitting long polygons that potentially crossed many historic fire boundaries. This procedure filled gaps that prevented polygons from being grouped together in latter analysis. The predicted time-since-fire ages were used to generate wildfire parameters such as age-class distributions and fire cycle. Three methods were examined to group forest inventory polygons together to predict fire event polygons: simple partitions, hierarchical clustering, and spatially constrained clustering. The predicted fire event polygons were used to generate polygon size distribution wildfire metrics. I found that there was a relationship between time-since-fire and forest inventory variables at this study site, although the relationship was not strong. As expected, the strongest relationship was between the age of trees in a stand as indicated by the inventory and the time-since-fire. This relationship was moderately improved by including tree species composition, harvest modification value, and the ages of the surrounding polygons. Assigning no-age polygons neighbouring values and grouping the forest inventory polygons improved the predicted time-since-fire results when compared spatially to the observed time-since-fire data. However, a satisfactory method of comparing polygon shapes was not found, and the map outputs were highly dependent on the grouping method and parameters used. Overall it was found that forest inventory data did not have sufficient detail and accuracy to be used to derive high quality time-since-fire information.

The aim and objectives. Overall: To improve forest inventory methods using laser scanning. Specific: To create methodological background for laser scanning in the Lithuanian forest inventory and to provide practical suggestions for the use of remote sensing technique in practice. To attain the objective, the following tasks were formulated: 1. To investigate the influence of forest cover on the digital surface model accuracy when it is drawn up based on laser scanning data; 2. To investigate estimation peculiarities of individual tree characteristics using laser scanning data in the Lithuanian forest conditions; 3. To investigate estimation peculiarities of stand characteristics using laser scanning data in the Lithuanian forest conditions; 4. Provide practical suggestions for the use of laser scanning technology in the Lithuanian forest inventory. Novelty and originality. In Lithuania it is the first research work of a similar nature in forestry, thus from this viewpoint all topics are new and significant. The results obtained studying the issues of surface digital models based on laser scanning data in forest-covered areas are actual to professionals and practitioners also in other fields of science in Lithuania. Other aspects of the work allowing to consider its originality on the international level: • The use of standwise forest inventory data along with laser scanning data both in the estimation of tree dendrometric characteristics and determination of forest... [to full text] / Tikslas ir uždaviniai. Tiriamajam darbui buvo iškeltas tikslas: Bendrasis: Tobulinti miškų inventorizacijos metodus naudojant lazerinį skenavimą Konkretusis: Sukurti lazerinio skenavimo naudojimo vykdant Lietuvos miškų inventorizaciją metodinius pagrindus bei pateikti praktinius pasiūlymus šiai nuotolinių tyrimų technologijai naudoti praktikoje. Tyrimo tikslui pasiekti išsikelti šie uždaviniai: 1. Ištirti miško įtaką skaitmeninio žemės paviršiaus modelio tikslumui, kai šis sudaromas lazerinio skenavimo duomenų pagrindu; 2. Ištirti atskiro medžio charakteristikų nustatymo ypatumus naudojant lazerinio skenavimo duomenis Lietuvos miškų sąlygomis; 3. Ištirti medyno charakteristikų nustatymo ypatumus naudojant lazerinio skenavimo duomenis Lietuvos miškų sąlygomis; 4. Pateikti praktinius pasiūlymus lazerinio skenavimo technologijai naudoti Lietuvos miškų inventorizacijoje. Naujumas ir originalumas. Šio darbo mokslinį ir praktinį naujumą reikia nagrinėti keliais aspektais. Pirmiausia, Lietuvos mastu tai yra pirmas miškotyros mokslinis darbas, nagrinėjantis lazerinio skenavimo taikymą miško inventorizacijoje, todėl visos temos yra naujos ir reikšmingos. Rezultatai, gauti tiriant skaitmeninių Žemės paviršiaus modelių sudarymo lazerinio skenavimo duomenų pagrindu klausimus mišku padengtose teritorijose yra aktualūs ir kitų Lietuvos mokslo sričių specialistams bei praktikams. Vertinant darbo naujumą viso pasaulio kontekste – dauguma naudotų sprendimų yra adaptuoti Lietuvos sąlygomis... [toliau žr. visą tekstą]

The aim of the study – improvement of on-going in Lithuania forest inventories based on satellite images and GIS databases. Specific objective of the study – to explore the possibilities of methods applied for the collection of information from satellite images and GIS databases and its processing in order to determine various Lithuanian forest characteristics, focusing on a variety of forest inventory schemes. 4 The goals of the study: 1. To discuss methodological assumptions for the use of satellite images and GIS database information to estimate various characteristics of the Lithuanian forests. 2. To investigate methodological assumptions for the application of two-phase sampling scheme based on medium-resolution satellite images for the estimation of Lithuanian forest characteristics. 3. To investigate the possibilities of application of medium-resolution satellite images on the basis of two-phase sampling scheme in stand-wise, mature stands and pre-harvesting forest inventories. 4. To investigate methodological decisions and application peculiarities of fast detection of changes in the forest using medium-resolution satellite images under Lithuanian conditions. Scientific novelty The development of methodological background for the use of medium-resolution satellite images and two-phase sampling-based schemes in Lithuanian forest inventory. The use of stand-wise forest inventory data as an auxiliary information together with medium-resolution satellite images in... [to full text] / Bendrasis darbo tikslas – Lietuvoje vykdomų miškų inventorizacijų tobulinimas kosminių nuotolinių tyrimų vaizdų bei GIS duomenų bazių pagrindu. Darbo konkretusis tikslas – ištirti kosminių nuotolinių tyrimų vaizdų ir GIS duomenų bazių informacijos, jos apdorojimo metodų galimybes nustatant įvairias Lietuvos miškų charakteristikas, orientuojantis į įvairias miško inventorizacijos schemas. Darbo uždaviniai: 1. Aptarti kosminių nuotolinių tyrimų vaizdų ir GIS duomenų bazių informacijos naudojimo vertinant įvairias Lietuvos miškų charakteristikas metodines prielaidas. 2. Ištirti dviejų fazių atrankos schemos taikymo vidutinės skiriamosios gebos kosminių vaizdų pagrindu vertinant įvairias Lietuvos miškų charakteristikas metodines prielaidas. 3. Ištirti dviejų fazių atrankos schema grindžiamo vidutinės skiriamosios gebos kosminių vaizdų taikymo sklypinėje, brandžių medynų bei prieškirtiminėje miškų inventorizacijose galimybes. 4. Ištirti operatyvaus pakitimų aptikimo miške, naudojant vidutinės skiriamosios gebos kosminius vaizdus, metodinius sprendimus bei jų taikymo Lietuvos sąlygomis ypatumus. Mokslinis naujumas Išvystyti vidutines skiriamosios gebos kosminių vaizdų ir dviejų fazių atranka grindžiamų vertinimo schemų naudojimo Lietuvos miškų inventorizacijoje metodiniai pagrindai. Sklypinės miškų inventorizacijos duomenų naudojimas kaip pagalbinė informacija kartu su vidutinės skiriamosios gebos kosminiais vaizdais dviejų fazių atrankos schemose vertinant miško charakteristikas... [toliau žr. visą tekstą]

Made available in DSpace on 2015-03-26T13:32:13Z (GMT). No. of bitstreams: 1 texto completo.pdf: 739954 bytes, checksum: 58f3879d83e13777643ea5fe0ef74001 (MD5) Previous issue date: 2011-06-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The general objective of this work was to evaluate if estimates of wood volume obtained from geostatistics techniques are more accurate than those obtained from classical statistical techniques.The study was conducted in stands of Tectona grandis L.f. with the dendometric volume trait measured in 101 plots laid along a sampling spacing with UTM coordinates, distributed in 17 plots with a total area of 391.87 ha. By adjusting the experimental semivariogram model, index of spatial dependence and cross-validation statistics it was obtained two estimates of the forest inventory: one by using the classical statistics and the other by using geostatistics. Methodology of systematic sampling with intensity of sampling of one plot for every 4 ha was used in the conduction of the classical estimation. A semivariogram model, used to assess the structure of spatial dependence of the variable volume per ha in the study area was adjusted in the prediction by geostatistcs. Then, block kriging was used to obtain predictions of the average volume of each plot. Comparison of the two methods of estimation was made based on the sampling error, in which a minor error with geostatistics was found. Therefore, it is concluded geostatistics should be used for forest inventory when there is spatial dependence structure in the region under study inasmuch as it provides more accurate predictions. / Este trabalho teve por objetivos geral avaliar se as estimativas do volume de madeira obtidas a partir de técnicas geoestatísticas são mais precisas do que as obtidas a partir de técnicas da estatística clássica. O estudo foi realizado em povoamentos de Tectona grandis L.f. com a característica dendrométrica de volume mensurada em 101 parcelas lançadas ao longo de uma malha de amostragem com coordenadas UTM, distribuídas em 17 talhões, com uma área total de 391,87 ha. Com o ajuste do modelo semivariograma experimental, do índice de dependência espacial e das estatísticas da validação cruzada, foram obtidas duas estimativas do inventário florestal: uma utilizando estatística clássica e a outra, geoestatística. Na realização da estimação clássica, foi considerada a metodologia de amostragem sistemática, com a intensidade de amostragem de uma parcela para cada 4 ha. Na predição por geoestatística, foi ajustado o modelo de semivariograma, utilizado para avaliar a estrutura de dependência espacial da variável volume por ha na área de estudo. Em seguida, utilizou-se a krigagem em blocos para obter as predições do volume médio de cada talhão. A comparação das estimações dos dois métodos foi feita com base no erro de amostragem, sendo encontrado um menor erro com a geoestatística. Conclui-se, assim, o uso da geoestatística para realização de inventário florestal, quando existir estrutura de dependência espacial na região em estudo, uma vez que ela fornece predições mais precisas.