Articles containing the keyword 'measuring instrument'

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.

• Lappi, E-mail: jl@mm.unknown
• Kotisaari, E-mail: ak@mm.unknown
• Smolander, E-mail: hs@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.

• Hari, E-mail: jh@mm.unknown
• Hari, E-mail: ph@mm.unknown
• Kanninen, 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.

• Mannerkoski, E-mail: hm@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. 

• Lönnroth, E-mail: el@mm.unknown