Acta Forestalia Fennica vol. 26 | 1923

The study is based chiefly on statistics of forest fires in the state forests in 1911-1921, published in the annual reports of Board of Forests (now Metsähallitus, Forest Service). Forest fires burned 37,200 hectares of forests in the state forests in 1911-1921. In Southern Finland the number of fires was 795 and in the Northern Finland 610. The frequency of forest fires is higher in south because of the denser population in the area. The average forest fire ranged 118 hectares in Southern Finland and 39 hectares in the north. Fires broke out most often because of careless use of fire. Weather conditions and the type of the forests influenced the risk of fire. In the north, risk for forest fire is lower because of the high proportion of peatlands. Only 14% of the fires burn the trees of the stand. In Southern Finland 50% of the fires and in Northern Finland 42% of the fires damage only part of the stand. Rest of the fires were surface fires that do not burn the trees. The value of damages by forest fires in the state forests in 1901-1922 was annually in average 139,400 Finnish marks.

The PDF includes a summary in English.

• Saari, E-mail: es@mm.unknown

The hard climate and other environmental conditions cause irregularities in the growth of trees in Lapland. Those changes weaken the characteristics of the tree for industrial use and hence lowers the timber price. The eccentricity is mainly caused by the strong wind burden.

The data for the article consists of 428 increment core samples from pine trees different ages, sizes and growth rate. There were collected in years 1910-1912 in Finnish Lapland, regions Utsjoki and Inari. The increment cores were collected on the height of 1.3 meters in south-north direction straight crosswise through the whole tree. The difference of length was measured between southern and northern half rays. Earlier studies show that the eccentricity remains the same in different heights of the tree. Hence studying the variations only on the breast height radiuses is possible.

The mean eccentricity is 12.3% and its maximum varies mostly between 20 and 25%. There are no differences in eccentricity between trees of different age classes or diameter. 

• Renvall, E-mail: ar@mm.unknown

Shrinking of timber when drying is a phenomenon that causes variation in measuring of timber in timber trade and on using the timber for construction or other purposes.   

The data for the article consists of 332 increment core samples from pine trees different ages, sizes and growth rate. There were collected in years 1910-1912 in Finnish Lapland, regions Utsjoki and Inari. The increment cores were collected on the height of 1.3 meters in south-north direction straight crosswise through the whole tree. The samples are 6mm thick. The diameter of the samples was measured immediately after making the sample and after several years’ storage in room temperatures. Also the age of the trees was determined.

The results are presented in tables. The degree of shrinkage varies heavily between the samples but stays anyhow between 1.5 and 3.9%. The mean degree of shrinkage for 314 samples was 2.9%. The results seem to indicate that the bigger the shrinkage the denser the annual growth ring system of the tree, meaning the slower the growth has been.  The older and of diameter bigger trees shrink less than younger and smaller trees. 

• Renvall, E-mail: ar@mm.unknown

A strip survey was performed in the counties of Sahalahti and Kuhmalahti in Häme, situated in Central Finland, to study the condition of the private forests. The forests cover 78% of the total land area of 37,420 hectares. The forest site types were relatively fertile. Scots pine (Pinus sylvestris L.) dominated forest covered 43%, Norway spruce (Picea abies (L.) H. Karst.) 30% and Betula sp. 23% of the forest land. The productivity of the forests could be improved by changing the species so that they suit the site. The volume of the standing crop is 67.2 m³ per hectare. The volume of the growing stock in the area could be 1 million m³ larger if the forests were nearer to the natural state. The annual growth of the forests is low, and could be much improved by correct forest management.

One of the aims of the survey was to study how the distance between survey lines should be adjusted to give acceptably accurate results, in a way that the strip-survey method can be adapted to large areas. The largest distance between the lines that gave results that differed less than 10% from the correct results, varied between 10 and 1.5 kilometres depending on the variables. For instance, to get accurate results for the rarest forest site types required line distance of 1.5 kilometres, but accurate results for the most common forest site types could be achieves with line distance of 10 kilometres.

The PDF includes a summary in German.

• Ilvessalo, E-mail: yi@mm.unknown

Work in the forestry, for instance, in logging operation during winter, has been important source of employment for the rural population in Finland. The study is based on statistics of forest work, felling, felled timber, workforce and horses used in the forest work in the state forests, published in the annual reports of Metsähallitus (Forest Service) in 1911-1913. The administrative and silvicultural work, for instance, sowing and planting, clearing of the felling area, building forest roads or work in the nurseries, range from 20% to 22% of all work done in the forestry. Major part of the work time is used in felling. To harvest one cubic meter of timber requires 0.3 man-days and 0.2 horse-days. The work is seasonal; felling work is available for about 90-100 days a year. Forest haulage is possible only in the winter, and for instance sowing and planting in the summer. The employees have secondary jobs in agriculture and in other sectors.

The PDF includes a summary in German.

• Helander, E-mail: ah@mm.unknown