Current issue: 54(1)
Under compilation: 54(2)
This lecture discusses the problem of the annual variation in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.), and its significance. A newly constructed instrument for field measurements of diameter growth is described, also the latest of the Royal College of Forestry’s series of machines for annual ring measurement. The method of constructing an annual ring index is also mentioned.
Examination of material from undisturbed stands in Northern Sweden has shown that the annual ring index series for pine are characterised by a relatively marked autocorrelation, which increases with latitude, implying that the annual ring index for a given calendar year is positively correlated with that for the year immediately preceding it. However, this seems not to be so in spruce, in which the annual ring index series is marked by the effect of the changes in cone production from the year to year. The annual ring index for spruce may be expressed in the form of climatic functions, according to which the index can be approximately calculated or known values of the meteorological variables contained in the function, in association with numerical expressions for the cone production. By means of a number of examples illustrating annual ring series from thinned stands. It is shown finally how the response to thinning can be presented in a more essential form from the variation in the annual rings, and how climatically corrected increment can be determined.
The PDF includes a summary in English.
The paper concerns relationship between climatic factors and annual ring indices mainly in Southern Finland. The studied index series were from papers of different authors and from different localities. The monthly mean temperatures and precipitation sums were derived from the measurements of meteorological stations. Effective temperature sums for different periods of the year were calculated from the monthly mean temperatures.
The autocorrelation functions were estimated for each index series. The autocorrelations at lag I were significant except for one series. Altogether the differences in the structures of the index series were noticeable, especially between the Scots pine (Pinus sylvestris L.) index series. The influence of climatic factors on the annual ring index variation was studied using cross correlation analysis, simple distributed lag models and transfer function-noise models.
The decisive factor for the annual ring index variation of Norway spruce (Picea abies (L.) H. Karst.) appears to be the effective temperature sum of the growing season. Warm periods during latter parts of previous summer had a negative effect on indices. For the variation of the Scots pine indices the most important climatic factors were the effective temperature sum of the latter part of the growing season and, especially on the arid sites, the precipitation sum during May-July.
The PDF includes a summary in Finnish.