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Upper Stem Diameter and Volume Prediction Strategies in National Forest Inventory (NFI)

Show simple item record 2019-05-08T14:40:28Z 2019-05-08T14:40:28Z 2019-05-08
dc.title Upper Stem Diameter and Volume Prediction Strategies in National Forest Inventory (NFI) en
ethesis.discipline Metsävaratiede ja -teknologia fi
ethesis.discipline Forest Resource Science and Technology en
ethesis.discipline Skogsresursvetenskap och -teknologi sv
ethesis.department Metsätieteiden laitos fi
ethesis.department Department of Forest Sciences en
ethesis.department Institutionen för skogsvetenskaper sv
ethesis.faculty Maatalous-metsätieteellinen tiedekunta fi
ethesis.faculty Faculty of Agriculture and Forestry en
ethesis.faculty Agrikultur- och forstvetenskapliga fakulteten sv
ethesis.faculty.URI Helsingin yliopisto fi University of Helsinki en Helsingfors universitet sv
dct.creator Stenman, Virpi
dct.issued 2019
dct.language.ISO639-2 eng
dct.abstract In forest inventories, the field data is needed as a reference data, calibration and for assessing the accuracy. Gathering the field data needs resources, such as work forces, equipment and data management operations. This means that time and budget as well as quality must be carefully considered when National Forest Inventory activities are to be planned. Therefore, the development of cost efficient, simpler, safer and more accurate and reliable field data measurement methods and tools are topics of great interest. One of the field measurement variables is the upper stem diameter, which has been part of the NFI field data set until the 11th NFI. The measured upper stem diameter helps to produce more reliable tree stem volumes with 3-parameter Laasasenaho volume model. However, only if the quality of the measurements is on an adequate level. The upper stem diameter has been traditionally measured with parabolic caliper assembled in the top of the 5-meter aluminium rod. This equipment combination takes time to assemble and disassemble, it is not very compact to be carried around as well as it can be a health and safety issue during the thunderstorm. Therefore Criterion, laser-based dendrometer performance was further examined in this study as an optional measurement equipment for future upper stem diameter field measurements. The Criterion upper stem as well as dbh measurement precision was analysed based on the 326 sample tree measurements with Sonar, Caliper and Criterion. The standard error for Criterion was 17,26 mm in dbh measurements for all species and 10,36 mm in d6 measurements for all species. The reference standard errors from earlier studies were 2,70 mm for dbh with Steel Caliper and 7,00 mm for d6 with Caliper. When analysing the Criterion performance with reference to mean of the measurements, the standard error in dbh measuements for all species was 9,72 mm and for d6 measurements 7,07 mm. Furthermore, the accuracy and precision were analysed with Bland-Altman technique, which is a suitable method for comparing two measurements of the same variable when both have some errors. The Bland-Altman results supported the earlier findings. Within and between observer analysis showed that the impact in measurement accuracy or precision is not caused by the observers. The comparison of the sample tree volumes produced the results that the relative standard error was increased by 2,13 % for all species when 2-parameter volume model was compared with 3-parameter model. Likewise, the relative bias was increased by 1,53 %. In efficiency experiment the scenario where only one sample tree with measured d6 was chosen from each of the sample plot and dbh percentile of p70 was providing most accurate and precise sample plot volumes with RMSE of 3,92 m3/ha and bias -0.78 m3/ha. The results show that there is a real challenge to achieve reliable and accurate upper stem diameter measurements and therefore new measurement methods need to be further studied and analysed. en
dct.subject measurement errors en
dct.subject forest inventory en
dct.subject accuracy en
dct.subject mittausvirheet fi
dct.subject metsän inventointi fi
dct.subject tarkkuus fi
dct.language en
ethesis.language englanti fi
ethesis.language English en
ethesis.language engelska sv
ethesis.supervisor Kangas, Annika
ethesis.supervisor Vastaranta, Mikko
ethesis.thesistype pro gradu -tutkielmat fi
ethesis.thesistype master's thesis en
ethesis.thesistype pro gradu-avhandlingar sv
dct.identifier.ethesis E-thesisID:faebfbdf-89d6-4e3e-93d6-d25728b11e36
ethesis-internal.timestamp.reviewStep 2019-04-04 14:25:16:554
ethesis.principalprofessor Holopainen, Markus
dct.identifier.urn URN:NBN:fi:hulib-201905081912
dc.type.dcmitype Text
dct.alternative Yläläpimitan ja puustotilavuuden ennustamisen strategiat valtakunnan metsien inventoinnissa (VMI) fi
ethesis.facultystudyline.URI none
ethesis.mastersdegreeprogram.URI none

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