Articles by T. Heikkilä

A mirror dendrometer consists of a hollow metal tube and three mirrors that are installed in the tube in a certain way. The tool is used to determine the diameter of a tree trunk above the reach. The article presents the formulas that can be used to correct the measuring mistakes that are caused by the wrong position of the dendrometer.

To determine the form class of a stand with the diameter measurements from a certain height the Jonson’s diameter relations tables can be used. The calculation of the form class for a stand is presented.

The PDF contains a summary in Finnish. 

• Heikkilä, E-mail: th@mm.unknown

The result of forest valuation depends heavily on the interest rate and hence determining the rate of interest for forest is the one of the most important tasks of forest valuation.

When defining the interest rate for forests, we need to take into account not only the common interest rate in the country, but also other factors. Those are for example the increase in timber price. By calculating the land expectation value we assume that costs for felling, regeneration and other management will rise by same percent.

The article presents the common formula of land expectation value and discusses its pros and cons. Because of the bad condition of Finnish forests, the forest valuation has not been used widely in practice and hence also the research on theme has been minor. The development of the forests in future will make the theme more relevant. 

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

• Heikkilä, E-mail: th@mm.unknown

Because the cross-sectional area of a tree stem is ellipsis, it cannot be determined exactly with only the diameter measurement.  The article presents a formula and the calculation of the exact cross-sectional area. If the cross-sectional area is calculated as arithmetic mean of two diameter measurement, varies the error between two limit values. The error becomes smallest by calculating the area based on the biggest and the smallest diameter measurements. 

• Heikkilä, E-mail: th@mm.unknown

There is little knowledge about the value increment of the stands that are about to become mature for felling. Sample plots were measured in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands in the most common forest site types in Rovaniemi, in northernmost Finland. Sample trees were chosen from dominant and codominant trees of the stand.

The value increments for the stands were generally very low. The average rotation of the studied stands would be 160 years. In the better forest site type, the increments of basal-area, volume and form height decrease slowly as the diameter of the tree increases. The value increment can give valuable information for intermediate fellings. They should be targeted mainly to large codominant trees and partly also in dominant trees that do not yet give logs, because their value increment is low.

The PDF includes a summary in German.

• Heikkilä, E-mail: th@mm.unknown