Articles containing the keyword 'selection cuttings'

This article reviews experiments and practical experience of forest management by the selection system in Finland. In an experiment of 25-year duration the annual growth of uneven-aged Norway spruce (Picea abies (L.) H. Karst.) stands was only about 50% of the average annual yield of even-aged stands in normal rotation on the same site.

In Finland the selection system is applicable under exceptional conditions only, viz. In intensively managed park stands and, on the other hand, on very marginal sites, e.g. on peat bogs and mountains near the tree-line. Even normal silviculture, however, may include cuttings which somewhat resemble selection system, e.g. removal of standards or restoration of mismanaged forests.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

The forest management practices in Finland are closely related to the industrial history in the country. The selection cutting method used previously has now been gradually disappearing, and differences in the quality of forest management can still be observed between different owner groups. The national forest inventories indicate that farm woodlots show the poorest silvicultural state among the ownership categories. This study analyses social and economic causes responsible for variation in the silvicultural state of farm woodlots managed jointly with a cultivated land holding. The study is based on the data of third national forest inventory in Finland, and a factor analysis was calculated using the data.

Although the model developed explains more than a half of the total variance of the level of silviculture, only less than third of this is clearly explained by economic and social factors. The remaining two thirds are explained by the ’nature factor’, which includes both economic and site factors. This affects the effect of different kinds of forest policy measures. Of the variables in the model, the strongest influence in the level of silviculture have income, size of woodlot, size of land area under cultivation and distribution of forest types. The differences in the level of silviculture between different woodlots and different districts, may be explained by the theory of cumulative process. Regional differences in economic phenomena cannot be explained without taking into consideration the social value hierarchy in each region, which determines the range of variation of economic variables.

The PDF includes a summary in English.

• Riihinen, E-mail: pr@mm.unknown

Permanent sample plots are considered to be the most reliable basis for investigations into structure and development of stands. Such sample plots, established since 1924 in Finland, have been used to study thinnings of varying intensity. These studies are yet too short to give comprehensive conclusions. It is also possible to base the studies on sample plots measured in managed forests and gain in this way information suitable for practical purposes. In this investigation development of stands treated by two different methods, repeated thinnings and repeated selection cutting were studied in pure, even-aged Scots pine (Pinus sylvestris L.) stands in Southern Finland, on three forest types.

The results show that volume increment level of naturally normal stands seem to have been reached easily by stands treated with repeated thinnings. With advancing age, the growing stock of thinned stands fall short from the natural stands. As thinnings have removed primarily the poorest trees, the increment is distributed over trees of a larger size more in thinned than in naturally normal stands.

When intensive cuttings have resulted in a relatively small growing stock, the decrease in volume increment leads to considerable decrease in volume. The size of the tree has no essential effect – within certain limits - on the volume increment of the stand, if the volume removed is similar. However, every intermediate thinning removing largest-sized trees may result in the prolonged rotation. Since the volume increment of an older stand is much smaller than earlier, intermediate thinnings removing largest-sized trees should be avoided if the aim is the greatest volume yield. The growing stock of middle-aged or older stands untreated or treated with slight cuttings only can as a rule be considerably reduced without volume increment declining.

The PDF includes a summary in English.

• Nyyssönen, E-mail: an@mm.unknown