The study material consisted of 13 rather old Norway spruce (Picea abies (L.) H. Karst.) and 17 Scots pine (Pinus sylvestris L.) stands located in different parts of Finland. In each stand the seed crops, radial growth and amount of latewood were measured during a period of about ten years. Seed production reduces the radial growth of spruce and pine in the year of seed maturing. In Southern and Central Finland also the proportion of latewood is reduced. Seed production accounts for about 14% of the variation in radial growth of a spruce stand growing in Lapland, and 27% in other parts of Finland. In pine stands the seed crop explains 19% of the variation in radial growth in Lapland, and only 7% in the rest of Finland. In spruce stands an average seed crop reduces radial growth by 14% in Lapland and 5% in the rest of the country. An abundant seed production causes a reduction of about 20%. In southern parts of Finland, the proportion of latewood is reduced by 5% in an average seed year and by 24% in a good seed year. In pine stands an average seed crop decreases the width of annual ring by 5%, and a good seed crop by 15%. Outside Lapland, also the proportion of latewood is reduced: in an average seed year by 5%, and in a good seed year by 16%. The reduction in volume growth of spruce stands due to an average seed crop was estimated to be about 10% in Lapland, and 6% in other parts of Finland. A prolific seed production causes a reduction of 20%. In old pine stands the reduction is 5% in an average seed year, and 15% in a good seed year.
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The effect of competition on the radial growth of Scots pine (Pinus sylvestris L.) was studied in three naturally regenerated stands located in North Karelia, Finland. The competition situation of an individual tree was described with various competition indices which depended on the sizes and distances from the neighbouring trees. One competition index explained about 50% of the variation in 5-year radial growth in one stand. If all stands were combined, one index explained 43.5%, two indices 48.9% and three indices 51.2% of the variation. In one stand, the best competition indices accounted for about 20% of that variation which could not be explained by tree diameter. If all three stands were combined, the best index explained 11% of the residual variation. About 40% of the variation in 5-year radial growth could not be explained by the diameter and competition indices.
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Crown and stem growth of young Scots pines (Pinus sylvestris L.) were studied in relation to photosynthate supply and light condition in a stand. The magnitude of needle and bud formation, and radial and height growth were to a great extent dependent on the photosynthate supply. However, in shaded conditions the growth of each characteristics was greater than expected on the basis of photosynthate supply. In the stem system this was especially apparent for height growth. Consequently, height growth was favoured at the expense of radial growth in shaded conditions. It also appeared that the basic density of wood was negatively related to both tree position and photosynthate supply.
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Radial growth of Scots pine (Pinus sylvestris L.) was investigated in seven camping areas located in Southern Finland. Radial growth reduction of 20–40% were found. The magnitude of this reduction was related to the amount of damage in the trees, and the age of the trees. A loss of humus, exposure of the roots and soil compaction were associated with the use of area but not related to the reduction in growth.
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The radial growth of Scots pine (Pinus sylvestris L.) stands at the age 30–40 years was measured retrospectively five years after the fertilizing and thinning of the stands. The abrupt effect of fertilizing was culminated 3–4 years after the treatment. The effect of thinning increased throughout the monitoring period. In stands that had been both thinned and fertilized, the effect of thinning was covered almost entirely by the effect of fertilizing, but fertilizing and thinning gave greater response than applying fertilizer or thinning only.
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Variation in the radial growth of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) was studied in 10 localities in Southern Finland. The aim of the study was to utilize the information on variation in the growth indices for growth estimation, and to evaluate the relative accuracy of growth estimation based on the data from increment boring, in comparison to other methods.
The climatic variation in periodic growth (5-year-period) in Southern Finland is about 11% of the normal level. The results suggest that the data from 10 localities can be used in the computation of the index series for Southern Finland and that the data from 10 relascope plots are required in the study of the climatic variation in tree growth in a given locality. The standard error of the estimate in actual growth estimation for past and future periods by the stand function method is about 23%, the errors of the method involving increment boring being 6% and 16% respectively in past and future growth estimation. The respective methods yield about 20% and 13% error in average growth estimation. With aid of the average growth indices for Southern Finland in local growth estimation the accuracy is distinctly improved, the error being equal to 12% only, while the accuracy in other cases is slightly improved.
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