Current issue: 58(5)
Articles containing the keyword 'measuring'
Category : Article
A measurement system developed for the parallel and real-time measurement of temperature, matric potential and oxygen diffusion rate (ODR) of a growth medium was assessed. The system consisted of a portable computer, a datalogger, temperature sensors, tensiometers and an ODR-meter with Pt-sensors.
For the measurements, proper sensor contact with the growth medium was needed. For matric potential measurement, appropriate shape and material of the tensiometer tips should be selected for different measurement purposes. The determination of oxygen diffusion rate is based on single, non-continuous measurements. The ODR-measurement required special care with the insertion and handling of the electrodes and selection of applied voltage. The ODR-measurement of a coarse peat medium was applicable only at matric potentials > -5 kPa. This measurement system was shown to be useful and suitable for accurate determination of thermal-, water- and aeration conditions of a growth medium under greenhouse conditions.
The PDF includes an abstract in Finnish.
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Heiskanen,
E-mail:
jh@mm.unknown
- Laitinen, E-mail: jl@mm.unknown
A third generation of forest tree gas exchange measuring system design for the use in the field is described. The system is designed to produce data for determining the dependence of the rate of tree photosynthesis, respiration and transpiration on environmental factors. The system consists of eight cuvettes, a tubing system, two infrared gas analysers, an air flow controller, a data logger, and a computer. The measuring cuvette is a clap type, i.e. it is mostly open, only closing during measurement. CO2 exchange is measured as the change in the cuvette concentration of CO2, and, transpiration is measured as the increase in water vapour concentration while the cuvette is closed. The environmental factors measured are temperature, irradiance and air pressure. The system was planned in 1987 and constructed in 1988. It worked reliably in late summer 1988 and the quality of data seems to be satisfactory.
The PDF includes an abstract in Finnish.
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Hari,
E-mail:
ph@mm.unknown
- Korpilahti, E-mail: eeva.korpilahti@luke.fi
- Pohja, E-mail: tp@mm.unknown
- Räsänen, E-mail: pr@mm.unknown
Berry yield of rowan tree (Sorbus aucuparia L.) was studied by picking and weighing the berries in a tree, counting the number of clusters by the eye, estimating the number of clusters by samples of 0.5 m2, and by counting the dropped berries. In the last tree methods average weight of berries in a cluster was assessed by weighing a sample of clusters. The size of the tree and the abundance of the berries influenced the choice of method. The first two methods suited for small trees, the third for a tall tree with berries in abundance, and the fourth for those cases where birds had eaten a large portion of the berries.
The berry yields of 88 rowan trees were studied in Central Finland in 1983, a year of exceptionally high berry yield. The yield of berries averaged 23 kg per tree, the number of clusters 1,249 per tree and the number of berries 42,500 per tree.
The PDF includes a summary in English.
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Raatikainen,
E-mail:
mr@mm.unknown
- Rossi, E-mail: er@mm.unknown
- Vänninen, E-mail: iv@mm.unknown
The choice of sampling method is of prime importance when seeking relevant information about the height distribution and spatial arrangement of seedlings in the regeneration surveys. It is suggested that the size of sampling plots should depend on the height of the seedlings. Tall seedlings should be sampled from a larger area than short ones since tall seedlings are more important for the future development of the stand. We suggest principles for a technical development task to construct a device which is easy to use in practical regeneration surveys and by which sampling can be made proportional to plant height or any desired function of height.
The PDF includes a summary in Finnish.
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Lappi,
E-mail:
jl@mm.unknown
- Kotisaari, E-mail: ak@mm.unknown
- Smolander, E-mail: hs@mm.unknown
A technique for instrumental scoring of damaged leaves on tobacco (Nicotiana tabacum) indicator plants caused by ozone in the lower atmosphere is being developed. The leaves are photographed in situ with an integrated unit, which illuminates the leaf from behind and keeps the camera in a well-defined position. By using microfilm and a minus green filter, it is possible to obtain negatives where the necrotic flecks appear as dark spots on a white leaf. The negatives are scanned in a TV-system and the size of the damaged fraction of the leaf is calculated by a microprosessor and is shown as a percentage of the leaf.
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Mortensen,
E-mail:
lm@mm.unknown
- Weisberg, E-mail: kw@mm.unknown
Light and economic FM-CW radar has been developed for controlling the bearing capacity of ice roads and landings on ice used for timber transportation and storage of timber in Finland. It was tested on natural ice and ice roads of three lakes in Southern Finland and one location on sea on the southren coast of Finland (a total of 166 observations). Ice thickness varied from 0 to 100 cm. Correlation coefficient between auger and radar measured ice thickness was r=0.99 and absolute error varied from -10 to +7 cm. The quality of ice had no influence, but by improving the interpretation of results, also the quality factors might be detected.
The PDF includes a summary in Finnish.
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Saarilahti,
E-mail:
ms@mm.unknown
Ashed tree samples from sound and decayed Norway spruce (Picea abies (L.) H. Karst.) were studied by means of fast neutron activation analysis, and for comparison, also by X-ray fluorescence analysis. In fast neutron activation analysis, the following elements were detected: (Na), Mg, Al, Si, K, Ca, Mn, Rb, Sr and Ba, and according to the results of the X-ray fluorescence method the elements present in the wood samples were: K, Ca, Mn, Rb, Sr and Ba. A general diminishing was revealed by both methods in most elemental concentrations studied, with exception of K and Rb, when going from a sound tree to a decayed one. The use of the ratio of the amounts of potassium to calcium as an indication of the degree of decay is therefore proposed.
The PDF includes a summary in Finnish.
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Raunemaa,
E-mail:
tr@mm.unknown
- Hautojärvi, E-mail: ah@mm.unknown
- Jartti, E-mail: pj@mm.unknown
- Laurén, E-mail: jl@mm.unknown
- Lindfors, E-mail: vl@mm.unknown
- Räisänen, E-mail: jr@mm.unknown
This paper describes the design and functioning of an electronic auxanometer designed for field use, and some results obtained with it. The changes in stem radius are monitored with a micrometer screw turned by an electirc motor. A potentiometer transforms the position of the screw into an electronic signal, which is recorded. The accuracy of the device is approximately 1–2 μm. Field experiments with the auxanometer are described and discussed. The accuracy of the device was found to be sufficient for measuring hourly changes in stem radius.
The PDF includes a summary in Finnish.
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Hari,
E-mail:
jh@mm.unknown
- Hari, E-mail: ph@mm.unknown
- Kanninen, E-mail: mk@mm.unknown
According to the available literature, the times when pulpwood limbing was made by axe and barking by hand tools, barking either had no effect on the pile density (if limbing quality was good) or increased pile density (if limbing was bad). When rotary barking machines are used, the branch stumps remain intact during barking. Therefore, if there are branch stumps in the pulpwood, barking decreases the pile density. Nowadays, when power saw limbing is a common practice in Finland, barking presumably greatly decreases the pile density, due to the fact that in power saw limbing branch stumps are numerous and high. Therefore, the method to estimate the solid volume of a pile of unbarked pulpwood are not applicable to barked pulpwood without modification.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
The investigation is concerned with testing chemical totalizer of radiation (Frankfurt radiometer) for use in measuring the components of a simple energy balance (latent heat = net radiation – sensible heat) so as to gain an estimate for evaporation. The meter is based on the temperature dependence of the inversion rate of sugar solution. The relationship is exponential. It was found that radiation sums for 2–6-day periods can be reliably determined with this meter when global radiation is below 20 MJ·m-2d-1. Determining sensible heat is noticeably inaccurate, and hence the calculation of evaporation values, too. In comparing evaporation from different types of ground and plant cover one thus has to be content with drawing conclusions on the basis of net radiation values. The totalizer is therefore only suited to describing radiation conditions.
The PDF includes a summary in Finnish.
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Mannerkoski,
E-mail:
hm@mm.unknown
The paper describes a method for the measurement of basic density of total tree chips. In the method the chips are placed in a container, which is immersed in a cylinder full of water, and the container is weighted at two levels. In the upper part of the cylinder the pressure against the air bubbles is smaller than in the lower level. In this method, the effect of air bubbles in the result can be eliminated. Besides this, due to homogenization of the material to be measured only small number of samples are needed for the estimation of the average basic density.
The PDF includes a summary in English.
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Kärkkäinen,
E-mail:
mk@mm.unknown
Light intensity inside the canopy varies considerably both in space and time. A new apparatus was developed which is disturbed as little as possible by the above-mentioned variation. The construction is based on the linear relationships between light intensity (measured using silicon diodes) and photosynthesis. This procedure permits linear operations (summing and integration) to be carried out on the output of the diodes without any loss of accuracy. There are five diodes in each assimilation chamber. A model, in which the independent variables include ligth, measured with the present equipment, and temperature, fits the photosynthetic rates well even inside the canopy.
The PDF includes a summary in Finnish.
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Hari,
E-mail:
ph@mm.unknown
- Huhtamaa, E-mail: mh@mm.unknown
- Pelkonen, E-mail: pp@mm.unknown
- Pohjonen, E-mail: vp@mm.unknown
- Salminen, E-mail: rs@mm.unknown
Category : Article
When the volume of the pulpwood was determined from the dimensions of the stack, the practice was to add an agreed percentage to the height of the stack which took account of the sinking of the stack as the wood dried. The stack was piled to the agreed added height, or the percentage was compensated when the stack was delivered to the buyer. The aim of the study was to determine a more accurate percentage to be used in the pulpwood sales.
The dimensions of a stack of Norway spruce (Picea abies (L.) H. Karst) pulpwood and the diameter of each log was measured during the drying. The 223 cm high pile sank by 0.8% to 221 cm, and the stacked cubic meter decreased from 4.46 m3 to 4.42 m3. However, the shrinkage of a solid cubic meter of the wood was 2.8%, markedly more than the sinking of the stack.
The PDF includes a summary in German.
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Wuoti,
E-mail:
ew@mm.unknown
Volume formulas have been developed already for long time but there are still some questions to be solved. The volume of a stem can be calculated based on measurements of diameter on various heights or based on mathematic formula. The article presents the formula development for that. The study is based on measurements of 24 pine stands.
The results of the new formula can be seen satisfactory with the relatively small data of this study. Coincidentally the formally best mean solution of the here compared volume calculation formulas was the one based on Denzin’s formula. There the deviation from total mean is almost zero.
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Lönnroth,
E-mail:
el@mm.unknown
The article presents the principle of working if a dendrometer and the mathematical theory behind it. Dendrometer is a new measuring instruments used to determine the height and diameter of a standing tree. The usability of the instruments is proofed to be very good thought there are some limitations to its use.
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Lönnroth,
E-mail:
el@mm.unknown
