Articles containing the keyword 'ojituskelpoisuus'

The study describes the relationships between a method developed by the author for the calculation of the profitability of forest drainage and the old biological method. The calculations were based on empirical data, and they aimed at finding out the effect of a variation in the profitability limit in the areas in hectares to be drained, and on the profitability of drainage. The study deals also with the profitability of present-day drainage activities. The results showed that the profitability coefficient (the ratio between the discounted increase in returns and the costs of drainage) averages 3.04 for the whole country. The corresponding value was 5.68 for Southern Finland, 3.19 for Central Finland and 1.67 for Northern Finland.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

There are about 155,000 ha of fen-like pine swamps (eutrophic pine bogs) in Finland, major part of which are situated in Northern Finland. In the classification system for drainability of peatlands, this type of peatlands had been placed in the first class. The study presents a new evaluation for the peatland type, based on vegetation and tree growth.

According to a previous study, the vegetation of fen-like pine swamps can be characterised by distinctive plant communities that seem to reflect the fertility and high pH of the underlying soil. In this study, the fen-like pine swamps were divided in two subtypes based on the vegetation: proper fen-like pine swamps and fen-like pine swamps with ericaceous shrubs. Both have distinctive vegetation, which is described in the article. The distribution of the subtypes seems to be different: fen-like pine swamps with ericaceous shrubs are more common in eastern parts of Northern Finland. The two subtypes could be divided in different drainability classes according to tree growth, proper fen-like pine swamps belonging to class 1 and fen-like pine swamps with ericaceous shrubs to class 4.

The article includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

Growth capacity of peatlands after draining depends largely on quality of the surface peat. The future growth capacity can be determined with considerable accuracy by the vegetation of the peatland. The aim of this study was to draw guidelines to identify the fertility of a peatland and its potential for draining based on its vegetation.

Certain species and plant associations were identified to describe the fertility of different peatland types. Brown mosses indicate an abundant nutrient content of the site, certain herbs moderately abundant nutrient content, sedges (Carex sp.) moderate nutrient content, shrubs poor nutrient content and vegetation indicating an oligotrophic peatland indicates excessively poor nutrient content. The article includes detailed descriptions of the vegetation of different peatland types.

Supplementary features, such as thin peat, flooded parts or abundance of Spangnum fuscum can be used as additional indications to determine the drainability of the site. The article describes an identification tool to determine the drainability of a peatland based on vegetation and the supplementary features of the peatland.

The article includes a summary in English.

• Huikari, E-mail: oh@mm.unknown

Silva Fennica Issue 39 includes presentations held in professional development courses in 1935 that were arranged for foresters working in public administration. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes different kinds of peatlands and their suitability to draining and forestry.

• Lukkala, E-mail: ol@mm.unknown

Systematic draining of peatlands begun in the state forests of Finland in 1908. It was considered necessary, because 41.4% of the state forests, 5.6 million hectares, consist of peatlands. Of the peatlands, 1.9 million hectares was estimated to be suitable for draining. Furthermore, paludification still continues in the forest lands. By the year 1926, a total of 52,275 hectares of peatland had been drained in the state lands.

Certain factors decide whether the peatland is suitable for draining: the growth increment capacity after draining, technical difficulties in draining, and difficulties in regeneration. Peatland type indicates the growth capacity of the drained peatland. The peatland should turn at least to Vaccinum forest site type or better type to be worth of draining. If the peat layer is thin, the quality of peat is an important deciding factor. The peatland may also be too expensive to drain due to, for instance, long ditches, main ditches difficult to dig, small inclination, uneven surface, and deep cavities at the bottom. The younger the trees of the stand, the faster the growth of the stand revives. The peatlands usually regenerate naturally provided there is sufficient seed trees, and there is seldom need for artificial regeneration.

The PDF includes a summary in English.

• Lukkala, E-mail: ol@mm.unknown

One of the factors that influence if a peatland is suitable for draining is the time required until fellings bring income, even if it the discounting calculations has uncertainties. This article discusses the factors that affect the economic profitability of draining peatlands.

The profitability of draining increases the more the yield or increase of the yield exceeds the costs of draining. Estimation of the yield is in Finland based on the peatland type, which reflects production capacity of the site. In addition, the growing stock of the site can vary in peatlands within same peatland type. The density and size of ditches affects the draining costs. Thus, productivity based on a peatland type alone does not describe well enough the drainability of a peatland area.

In Finnish classification of site quality of the peatlands, the treeless bogs and rich fens have been given too high a class compared to well stocked spruce swamps and pine swamps. Also, the drainability of two spruce and pine swamps can differ markedly in economic point of view if the tree’s quality, volume and ability to recover differ. The article discusses different methods to assess profitability of draining that have been descibed in the previous studies. It is suggested that the classification of peatlands by their drainability should be more selective.

The PDF includes a summary in German.

• Keltikangas, E-mail: vk@mm.unknown

According to the theory of peatland types, particular peatland types, after sufficient drainage, change into certain forest types. It has been found, that the range of forest types in peatlands in different stages of draining is as large as on mineral soil; and comprise Cladina, Calluna, Vaccinium, Myrtillus Oxalis-myrtillus and grove types. Poor peatland types change into poor forest types, better for better types. However, a Swedish scientist Mellin suggested that after effective drainage especially oligotrophic bogs, when well drained, change usually into Myrtillus type.

The different conclusions are due to the fact that the same bog type may develop into different forest types according to the effectiveness and duration of the drainage. Greater the decay of the peat bog layer, the more exacting is the type of vegetation which appears. Bog types of classes V, IV and III (Finnish classification of site quality) change into a Myrtillus type, as do the poorer peatland types of class II. The types vary, however, in their economical drainage value. The fact that bogs which in their natural stage are clearly different in their site quality change after through drainage into the same forest type, is explained by the chemical quality of the peat. However, class I and the best types of class II bogs change into better forest types because they as eutropchic bogs are richer in nitrogen and lime. This difference persists despite of effective draining.

It has been shown that the development of eutrophic peatland types at the forest type stage also differs clearly from the development of oligotrophic peatland types. The Finnish classification of drainage value shows correctly the relative drainability when using normal spacing of ditches. The notes on forest types on mineral soil should, however, be replaced by corresponding notes on the transitive types between bog and forest types.

The PDF includes a summary in Swedish and English.

• Keltikangas, E-mail: vk@mm.unknown

The study is a part in a more comprehensive series of investigations into the profitability of forest improvement measures. The present paper describes a new method for calculation of the suitability of various peatlands for forest drainage. According to this method, the net profit is calculated as the difference between the gross profit and the costs, and the profitability coefficient, as the ratio between the gross profit and the costs. The most important factors used for calculation of the gross profit and the costs are as follows: the site quality index, the volume of the tree stand capable of development at the time of draining, the temperature sum and the stumpage development at the time of draining, the temperature sum and the stumpage price. For use in the field, simplified auxliary tables have been worked out.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown