Articles containing the keyword 'suot'

The paper is a review on utilization of peatlands in forestry in the countries of boreal zone: Finland, Norway, Sweden, Canada, the United States and the Soviet Union. First, the concept of peatlands, the types of peatlands throughout the zone are defined, and the use of natural peatlands is described. Finally, the drainage of peatlands for forestry purposes in the countries is reviewed. According to the statistics, a total of 13 million ha of peatlands have been drained in Fennoscandia and the Soviet Union.

• Päivänen, E-mail: jp@mm.unknown

Refertilization with PK, about 15 years after the first fertilizer application, increased tree growth and the amount of nutrients in tree litter in Scots pine (Pinus sylvestris L.) and birch (mainly Betula pubescens Erhr.) stands on a drained fertile mire in Northern Finland (65°34 N’, 25°42’ E). The increase in growth and nutrient contents after refertilization was greatest in the mature pine stand where the application of nitrogen and micronutrients gave an additional response compared to the PK-application.

The PDF includes an abstract in Finnish.

• Paavilainen, E-mail: ep@mm.unknown

The area of stands studied by line plot survey was 594 ha. On the basis of the length of the inventory line the estimated proportion of harvesting strips was 14% and that of ditch openings 6% of the area. The calculated strip road spacing was 29 m. The option of the minimum diameter made it difficult to use the number of stems as criterion for thinning intensity. Thinning intensity evaluated according to the basal area had been stronger than recommended with low values of dominant height and milder with high values. The estimated removal according to stumps was 38 m³/ha on the average between the strips. The real removal has, however, been larger than that, as the strip road openings are made in connection with the first thinning.

The PDF includes an abstract in English.

• Rantonen, E-mail: hr@mm.unknown
• Päivänen, E-mail: jp@mm.unknown

The effect of drainage on structure of tree stands is analysed by comparing the average structural characteristics (e.g. diameter distribution) of stands in the data for different drainage age classes and selected site types. The material consists of ca. 4,400 relascope sample plots, which are part of a large drainage area inventory project. The uneven-aged structure of the virgin peatland forest is preserved for several decades after drainage. This is enhanced by the post-drainage increase of small-diameter trees, especially birch. The number of trees per hectare increased during a period of ca. 30 years and levelled off thereafter. The increase in the number of saw log stems is clearly related to the fertility of the site and its geographical location.

The PDF includes a summary in English.

• Hökkä, E-mail: hh@mm.unknown
• Laine, E-mail: jl@mm.unknown

Young Norway spruce (Picea abies (L.) H. Karst.) are susceptible to early summer frost damage. Birch (Betula pubescens Ehrh.) naturally colonize rich or fairly rich drained peatlands after clear cutting, and can provide protection for developing seedlings. The report describes the development of spruce stands after various types of handing of the birch nurse crops.

Different proportions of birch and spruces did not have any influence on the spruce stand production. In cases where the nurse crop stand is removed when the spruce stand age was 20 years and height 4 m the spruce suffered badly but recovered with time, reaching the spruce stand growing under a nurse stand within the next 20 years. The height growth of spruce depends on the density of the nurse stand, especially on fertile sites. The development of diameter growth also depends on the density of the nurse trees. Removal of the nurse stand in spruce stands on the sites concerned should be done when the spruce stand is 20 years old and at the height of 4 m.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

A survey was carried out among forest foremen and forest technicians to record their observations on the value of various swamp and forest types as producers of berries and on the effect of drainage of peatlands upon the berry yields. Comparative agreement existed on the best blueberry (Vaccinium myrtillus L.) forest types and on the best lingonberry (Vaccinium vitis-idaea L.) forest types of rather dry upland sites. Fuscum pine swamps or fuscum bogs were considered best for the most part as regards the yield of cloudberry (Rubus chamaemorus L.). The replies showed rather great dispersion.

Agreement existed as well on the relation between drainage of peatlands and the yields of our economically most important swamp berries, cloudberry and cranberry. 90% of those responding were of the opinion that drainage reduces the cloudberry yield in the long term and a full 97% indicated that cranberry crop diminishes as well.

The PDF includes a summary in English.

• Sepponen, E-mail: ps@mm.unknown

The effects of variations in the intensity of drainage and NPK fertilization on the natural regeneration and planting results and the subsequent development of seedling stands under various climatic conditions on drained nutrient poor pine bogs was investigated in a 16-year-old study.

Comparison of height development of Scots pine (Pinus sylvestris L.) stands on drained peatlands to that of pine stands growing in mineral soil sites show that in Southern Finland the most efficient forest improvement measures (10 m ditch spacing and 1,000 kg/ha NPK-fertilization) resulted in growth that corresponds a to a height index of a stand in a Vaccinium type site. Less efficient treatment (30 m ditch spacing and no fertilizer) resulted in growth corresponding the development of young stand in a Calluna type site. In Northern Finland the effect of fertilization on height growth was almost negligible. This is possibly due to a decrease in the nitrogen mobilization from south to north of Finland. Thus, it seems evident that fertilization of young Scots pine stands on nutrient poor drained peatlands can be recommended only in the southern part of the country.

The effect of ditch spacing is same in the whole country. The narrower the spacing the better the height growth. In the south planted stands thrive better than naturally regenerated stands, but the situation is reversed in the north.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Lepola, E-mail: jl@mm.unknown

The aim of the paper was to describe the development of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) seedling stands on drained peatlands and to find out the principal factors influencing their growth. The material under survey consists of 180 sample plots distributed from southern coast of Finland to the Polar Circle.

The most important growth factors have been the accumulated temperature sum, site quality, drainage intensity and silvicultural condition, such as the density of the stand, the proportion of birch in the stand, and the amount of possible shelterwoods. The influence of these factors, and to some extent the influence of fertilizing, and the disturbing effects of some forest damages, such as frost, growth disturbances and elk damages were investigated. Comparisons of the development in the seedling stands on drained peatlands with the known development of seedling stands in mineral soils were made.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The objective of the investigation was to determine the differences between timber grown on a peatland before and after draining, in respect of compressive strength parallel to the grain, static bending strength and density. In addition, the characteristics of boundary zone between the wood formed before, and after the draining with wider growth rings was studied. 41 Scots pine (Pinus sylvestris L.) and 22 Norway spruce (Picea abies (L.) H. Karst.) trees were studied.

The compressive strength of pine usually decreased from the butt end upwards, but no trend was observed in spruce wood. In coniferous trees, wide-ringed wood formed subsequent to draining was slightly lighter than the close-ringed wood produced prior the draining. The density of pine as well as spruce increases as the width of the growth rings decrease up to a certain limit. The strength of the different kinds of wood seems to decrease from the butt end upwards.

In both species, the compressive strength parallel to the grain and the bending strength are lowest in such wood that contains exclusively wide-ringed wood formed subsequent to draining. Also, compressive and bending strength increase with decreasing width of the growth rings. The longitudinal shrinkage of compression wood in spruce was several times that of normal wood, and the bending strength was lower than that of normal wood particularly in spruce. The compressive strength parallel to the grain in dry condition was, however, higher than in normal wood both in pine and spruce.

The PDF includes a summary in English.

• Ollinmaa, E-mail: po@mm.unknown

Questionnaires were sent out to determine the volume of wood harvested from peatlands during 1978 and the harvesting problems encountered. In total there were 110 responses which accounted for 8 million m3 of wood harvested, of which 1.0 million m3 (14%) was harvested from peatlands. The largest proportion of wood harvested from peatlands was during the winter. Most of the respondents reportet that they wait for the soil frost to set before harvesting is started on peatlands. Respondents indicated a total of 263 machines bogging down in to the soil or, for 1978, a total for Finland of 750 to 1,000 machines.
The PDF includes a summary in English.

The PDF includes a summary in English.

• Saarilahti, E-mail: ms@mm.unknown

The present paper deals with the most important factors of peatland hydrology and the influence of forest drainage on the hydrology of peatland itself and its surroundings. It is compiled of six seminar papers written by students in the Department of Peatland Forestry in the University of Helsinki. Special attention is paid to the hydrological consequenses of the maintenance of drained areas. Also ways and measures to minimize the negative environmental effects of these treatments are discusses.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Joensuu, E-mail: sj@mm.unknown

The aim of this study was to determine under what conditions and with what premises the growing of Betula pubescens Ehrh. is an economically competitive alternative to the growing of Scots pine (Pinus sylvestris L.) in drained peatlands. The basic material consisted of all drainage projects in Ostrobothnia in Western Finland in 1937–38 and 1957–59, according to the archives of the Central Board of Forestry Tapio, including such areas that were at least moderately fertile and had birch dominated young stands or no tree cover. A total of 202 sample plots were measured.

According to the results, the discounted timber yield of the thinned B. pubescens stands is about 10% greater than that of untreated stands. The removing of birch seedlings and the subsequent growing of fully stocked Scots pine is more profitable than growing B. pubescens stands only if the establishment and subsequent development of the pine stand involve no costs. If the site in question is a fertile open drained peatland, establishment of a pine stand is obviously a better financial proposition than a naturally regenerated birch stand. However, if there is already a fully stocked young birch stand on the site, it is more economical to let it grow using a shortish rotation time.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The ash content has been found to correlate with the fertility of peatlands. Relationship between height of 80-year-old stands and ash content of peat in topmost 30 cm layer was examined in Lithuanian conditions. On drained peatlands with ash content of peat from 3% to 8% pine stands increase in height. Ash content of peat being about 7% Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on drained sites are found to be of equal height. Ash content of peat more than 8–9% has no significant effect on growth of pine or spruce stands. Birch (Betula verrucosa (B. Pendula Roth.) and Betula pubescens Erhrh.), stands are less sensitive to ash content of peat compared with other species. Black alder (Alnus glutinosa L. Gaertn.) stands occurred in sites with ash content of peat more than 8–10%. The height of the stands become equal both in drained and undrained sites in the cases where ash content of peat is about 16–18%. Ash (Fraxinus exelsior L.) stands attain high productivity on drained sites with ash content of peat about 20%.

The PDF includes a summary in English.

• Kapustinskaité, E-mail: tk@mm.unknown

During the next decade there will be a marked increase in the allowable cut in drained peatlands. At the same time, the mechanization in logging proceeds, and in short-distance haulage the use of forwarders will increase. This study, based on literature and some observations, deals with logging conditions in drained peatlands with special reference to the suitability of heavy logging machines for use in such terrain. In addition, soil frost and the bearing capacity of the frozen peat soil were studied.

Freezing of the soil in a drained peatland area depends prevailingly on the weather conditions during early winter. The factors influencing soil freezing of a drained peatland are completely different from those regulating the freezing of natural peat soils. The frost penetrates in general deeper in the drained than virgin peatland. The topmost peat layer does not, however, freeze uniformly. Generally speaking, the bearing capacity of a drained peat soil is lower than that of undrained peat due to lower water content.

It is concluded that heavy logging machines are probably not fitted for use in drained areas on peatland even if the average soil frost values recorded would suggest it. Moreover, because of their extremely superficial root systems, peatland forests are exposed to damages by heavy machines in thinning operations.

The PDF includes a summary in English.

• Hannelius, E-mail: sh@mm.unknown

The paper describes the results obtained from an investigation into the effect of ditch spacing, ditch depth and furrowing on ground water table and on development of a Scots pine (Pinus sylvestris L.) plantation on open small-sedge bog in Central Finland (60° 50’ N; 24° 20’ E), drained in 1967. The area was planted in 1968 with 2+1 Scots pine transplants, and fertilized with Y fertilizer for peat soils. The seedlings were measured in 1972.

The depth of the ground water table was greater, the narrower the ditch spacing. The water furrows shortened the duration of the high ground water and lowered the ground water table particularly in the case of ineffective drainage. The narrower the ditch spacing within the blocks, the higher were the young trees. On the other hand, the differences in the height of the trees between the ditch spacings were eliminated by the effect of the furrows.

The PDF includes a summary in English.

• Päivänen, E-mail: jp@mm.unknown

The paper deals with the relationships between macronutrients, ground vegetation and tree crop on a drained peatland area in Central Finland. The former herb-rich spruce swamp was drained in 1930s. The Norway spruce (Picea abies (L.) H. Karst.) stand was established by planting under a nurse crop of birch, which was removed later.

There was a negative correlation between the thickness of the peat layer and the volume and mean height of the growing stock. This was found to depend on the negative correlation prevailing between the potassium content of the topmost peat layer and the thickness of the peat cover. The deficiency of potassium is clearly discernible as deficiency symptoms in the needles, the intensity of which showed a strong correlation with the stand characteristics studied. Among the nutrient characteristics of the topmost peat layer, total potassium and the N/K and P/K ratios showed the closest correlation with the stand characteristics. The communities into which the ground vegetation was divided differed from each other with regard to the calcium content of the peat substrate.

The PDF includes a summary in English.

• Mannerkoski, E-mail: hm@mm.unknown

The paper describes the results obtained from an investigation into the effect of thinning of different intensity and fertilization on the depth and water equivalent of the snow cover as well as on the depth of the soil frost in a young Scots pine (Pinus sylvestris L.) stand growing on drained peatland in Central Finland. Thinnings and fertilization was carried out in 1968, and the snow cover was followed in the winters 1970/71 and 1971/72.

Only extremely heavy thinnings (60% of the volume) seemed to increase the depth and water equivalent of the snow cover. The indirect effect of fertilization on the snow cover was insignificant. In the clear-cut sample plot of the study, soil frost was either not found at all or the depths of the frozen soil layer was smaller than in the other plots. When deciding the silvicultural measures to be taken in the case of tree stands growing on drained peatlands, there seems to be reason to avoid radical thinnings. Otherwise, the favourable influence of the trees on a site on its water relationships will be diminished.

The PDF includes a summary in English.

• Päivänen, E-mail: jp@mm.unknown

The aim of the present study was to assess whether two-year old Betula verrucosa Ehrh. (now Betula pendula Roth.) transplants can be used in afforestation of drained peatlands and what factors affect the development of the young trees. The seedlings were planted in 1967. The site was repair planted next spring due to mortality caused by a undefined fungal disease, and the plantations were fertilized with NPK fertilizer (soil application. The seedlings were measured twice a year until the autumn 1970.

Only 28% of the original transplants, and 73.4% of the repair plantations were alive in 1970. In some cases, fertilization improved the results, while in others it was detrimental to the trees or had no effect on survival. According to peat analysis, the poor survival and development of the plants could be due to the too high ratios of N/Ca and N/P. Stunted or dead trees displayed often necrosis caused by Godronia multispora. According to the experiences, Betula verrucosa plantations are inferior to those obtained with Scots pine (Pinus sylvestris L.). In addition, the results indicate that in old draining areas calcium and phosphorus are often too low in comparison to nitrogen.

The PDF includes a summary in English.

• Lehtiniemi, E-mail: tl@mm.unknown
• Sarasto, E-mail: js@mm.unknown

The possibilities of using a pot method to determine the need for fertilizer application were studied. Seedlings of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) were grown in peat samples that had cylindrical shape with a diameter of 25 cm and height of 35 cm. The samples represented three different peatland types, and were fertilized with two levels of phosphorus, potash and nitrogen. Two transplants were planted per pot. The development of the seedlings was followed for three years.

Phosphorus seemed to be of greatest importance for the growth of the seedlings, but nitrogen was also required in the poorest peatland type. Potash did not give statistically significant results. NPK application gave the best response. The usability of the method was studied by following the development of the roots. It seemed that the diameter of the pots was too small and restricted the growth of the root systems.

The PDF includes a summary in English.

• Erjala, E-mail: pe@mm.unknown
• Saramäki, E-mail: js@mm.unknown

The changed in size and shape of ditches made by draining plows and tractor diggers were followed over a one-year period after the draining in four different peatland types. The material consists of 51 ditches made with each method in dwarf-shrub pine bog, herb-rich spruce swamp, in herb-rich sedge bog and sedge pine bog. The measurements were made immediately after the digging, and one month and a year later.

Ditches made by plowing and surrounded by peat became shallower quickly during the first 2–3 days after plowing due to the pressure of the surrounding peat. Ditches made with tractor diggers did not become shallower as fast, and their bottom did not widen to the same extent than plown ditched. During the first year, machine-made ditches change in a same way as handmade ditches, especially when compared to ditches made by tractor digger.

Immediately after digging the ditches made by tractor digger were 10 cm deeper and 0.13 m³ larger than plown ditches. One year later the values were 7,5 cm and 0.09 m³, respectively. Plown ditches made in the peat were 14.4 cm deeper than ditches that penetrated into the subsoil, for tractor digger the value was 13.2 cm. Ditches made with a tractor digger were deeper than plown ditches both in soils with deep and shallow peat layer.

The changes were largest and fastest in the wettest peatland type herb-rich sedge bog. In herb-rich spruce swamps, which have a shallow peat layer, the shallower plown ditches kept their form better than ditches dug by tractor digger.

The PDF includes a summary in English.

• Timonen, E-mail: et@mm.unknown

The paper describes the results obtained from an experiment of fertilization of drained treeless peatlands in connection of planting in three sites in Central Finland. Scots pine (Pinus sylvestris L.) seedlings 2+0 was used. The fertilizer (Y-fertilizer for peat soils, 14% N, 18% P₂O₅, 10% K₂O) was applied in rates of 0, 20, 40 and 80 g/transplant. The fertilizer was strewn either around the plant within a circular patch of 20 cm in diameter, in a ring with a radius of 10 cm and in a ring with a radius of 20 cm. The seedlings were measured two and five years after planting.

The greater the quantity of fertilizer applied and the closer it was applied to the plant the higher was the mortality of transplants. Fertilization increased the mortality during the first two growing seasons after application. Later, however, the mortality decreased to a similar level irrespective the way the fertilizer was applied. In the beginning of the second growing season the fertilized plants showed considerably better height growth than the control plants. The smallest quantity of fertilizer applied produced almost full increase in growth. The pattern of application of the fertilizer had little effect on the growth.

It was concluded that a use of small amounts of fertilizer can be recommended in connection with planting and that it should not be applied very near the seedlings.

The PDF includes a summary in English.

• Seppälä, E-mail: ks@mm.unknown

The aim of the present study was to increase the knowledge of the anaerobic conditions prevailing in virgin peat soils of different kinds, and on the fluctuation of the aerobic limit. Silver rod method was used to indicate anaerobic conditions and to locate the aerobic limit. The material included 18 peatland sample plots on treeless bogs, in pine bogs and in spruce swamps in Southern Finland. Observations of the discoloration of the silver rods and measurements of ground water level were made from 8 June to 13 August 1968.

The results show that the location of the aerobic limit is dependent of the depth of the ground water table, and usually lies 5–15 cm above the ground water table. Down to 10–20 cm below the aerobic limit, where it reaches maximum, the rate of decomposition of sulfurous organic matter is positively correlated with the distance from the aerobic limit. Deeper it gradually decreases, and in the depth of 25–35 cm no hydrogen sulphide seems to be released.

In the forested peatland types the volume of the growing stock and the increment were dependent on the depth of the aerobic limit only when nutrient content and pH of the peat was more or less constant. Where the aerobic limit was close to the ground surface but the nutrient contents were relatively high, the volume of the growing stock may be comparatively high. Birch (Betula sp.), better than the conifers, is able to stand conditions poor in oxygen. The growing stock was poor in sites where the aerobic limit was near the ground surface, but the nitrogen and phosphorus contents were high, or vice versa. Consequently, aerobic limit is of great importance as an indicator of site quality.

The PDF includes a summary in English.

• Lähde, E-mail: el@mm.unknown

This paper presents the results of a contest performed on behalf of the Finnish bank Kansallis-Osake-Pankki and the Central Forestry Board Tapio on growing trees on peatlands. Over 5,000 sample plots were established on drained peatlands in various parts of Finland. The aim was to achieve a best possible growth of seedling stands on peatland. The factors influencing the growth of 85 best Scots pine (Pinus sylvestris L.) and 60 best Norway spruce (Picea abies (L.) H.Karst.) sample plots were studied.

The height growth of the seedling stands decreased towards the north. Fertilization seemed not to decrease the regional differences; rather on the contrary. On the other hand, fertilization increased height growth, but evidently so that the increase obtained was greater in the southern than in the northern parts of the country. Light fertilization (50 kg/ha of K₂O and 60 kg/ha of O₂P₅) caused a clear increase in height growth while heavy fertilization (100 g/ha of K₂O and 120 kg/ha of O₂P₅), had same effect but to much greater extent than the former. Spruce seedling stands in particular benefitted of the heavy fertilization.

Fertilization did not eliminate the original differences in the quality of the sites in question, but these could still be seen in the height growth after fertilization. The effect of drain spacing on the height growth was not very clear. In dense seedling stands (800 seedlings/ha) the height growth of the dominant seedlings was greater than that obtained in stands of lower density. Hold-overs caused a decrease in the growth of the seedling stands.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Ouni, E-mail: jo@mm.unknown

The present paper is a preliminary report of a project designed to determine the order of profitability of various forest improvement measures – seeding and planting, drainage, and fertilization – in various types of stands and in different parts of the country on drained peatlands. Sample plot data on the effect of draining on increment was derived from areas drained 28– 36 years ago. The study was carried out in the southern half of Finland.

The observations on increment changes are based on two measurements of the sample stands 12 years apart. Supplementary calculations indicate that the stands on drained peatland, depending on site quality and tree species, have either continued to grow like mineral-soil sites of similar fertility or have somewhat increased their growth rate.

The effect of draining intensity was studied using strip measurements. It was found that both the total amount of wood produced (current stand + cutting removal + natural removal) and the current annual volume increment for the 5-year period systematically decrease as the ditch interval increases. The decrease is, however, relatively slight. In Eriophorum vaginatum pine swamps, the total amount of wood produced and the increment show a decrease of ca. 20% with an increase in ditch interval from 20 to 60 metres. In other sites, the decrease is ca. 5-10%

It can be concluded that if the increase in ditch interval do not result in considerably poorer timber assortment distributions than indicates by stand production and increment, it is profitable to pan for a relatively large ditch interval and a slightly smaller than maximum wood production. Supplementary data and check calculations may cause some changes in these preliminary results.

The PDF includes a summary in English.

• Seppälä, E-mail: ks@mm.unknown

Due to mechanization of draining of peatlands, also open peatlands have been included in the draining projects due to technical reasons. Some research has been published on afforestation of open drained peatlands, but there is yet no experiments that reaches the entire development of the stands. The purpose of this paper is to discuss the possibility of extending the planting season of Scots pine (Pinus sylvestris L.) over the entire growing season in drained peatlands, where the water condition of the site is probably not the factor limiting forest development. An open low-sedge swamps in Southern Finland were planted in early summer and two weeks in midsummer in 1967.

In the light of the results, planting Scots pine would seem possible in drained peatlands throughout the growing season. However, plants may suffer considerably from lifting for the plantation in August. The success of planting at the turn of September and October is also uncertain. The nursery must be situated close to the areas to be planted, since the transportation and handling of plants during the growing season must be carried out with extreme care. The seasonality of planting work could be decreased by extending the planting season. In the future, several transplant storing methods should be tried out in connection with similar planting-time experiments.

The PDF includes a summary in English.

• Päivänen, E-mail: jp@mm.unknown

This paper describes the preliminary results of Scots pine (Pinus sylvestris L.) seeding and planting trials on drained peat soils.

The results showed that a perpared peat surface was a better surface for seeding than the unprepared one. Planting of 2+1-year seedlings succeeded better than planting 1-year seedlings. Planting on the turf gave better survival than planting on the unprepared soil surface. The whole growing season was suitable time for planting Scots pine seedlings except May when the peat soil under the surface was still frozen.

Using fertilizers in connection with planting was surveyed in two ways. Mortality of seedlings increased when they were top-dressed with NPK fertilizer. Using a so-called spot fertilizing with several combinations of fertilizers resulted in K and N tending to increase the mortality of seedlings, but P decreasing mortality.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Päivänen, E-mail: jp@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

About one third of the land area of Finland is covered by peatlands, furthermore, some mineral soils are troubled by excess water. Due to the prevalence of peatlands, forest drainage has been the most important form of forest improvement work. Consequently, peatlands have been an extensively studied topic within forest sciences in Finland. This paper gives a review on the central research subjects in science of peatlands, introducing little less than a hundred of the hundreds of publications published in the field. The author describes in more detail research on the formation and area of peatlands, peatland types and their suitability for forest draining, site factors on peatlands, techniques of forest ditching and the management of peatland forests.

The PDF includes a summary in Finnish.

• 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

Silva Fennica Issue 92 includes presentations held in 1956 in the 8th professional development courses, arranged for forest officers working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

In 1925-1944 the Finnish Swamp Cultivation Association (now Finnish Peatland Society, Suoseura) carried out research on the arability of peatlands, mostly on state lands that were the main object of settlement work and the arability of which had been little explored. Later the work has been transferred to the Settlement Department of the Ministry of Agriculture (ASO) and some other authorities. ASO has prepared arability maps based on the nutrient analysis of the lands.

• Kotiaho, E-mail: ak@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

According to the second National Forest Survey, peatlands covered before the World War II 11,156,000 hectares, 32% of the land area of Finland. The early drainage of peatlands in 1700th century had aimed at preventing frost and increasing area of agricultural land. The experiences proved that drainage of wet forests was lucrative also in the point of view of forestry. The drainage of state-owned forest lands was promoted by the Crown Forest Committee in its report in 1900. The systematic drainage work in state lands begun in 1909. In the end of 1920s 500-700 km of ditches was dug annually.

The drainage of private lands begun after 1928, when forestry promotion work in private forests begun. By the end of 1950, 4,815 forest drainage projects had been approved by the Forest Service in the private lands. In addition, 286,000 ha of peatlands was drained on work organized by the central forest associations in 1930-1950, and 239,272 ha by timber companies in 1902-1950. The drained area totalled 755,892 ha. The area of drainable and drained peatland was estimated to be 4.4 million ha.

The article includes an abstract in English.

• Tirkkonen, E-mail: ot@mm.unknown

The aim of the study was to develop an determination method to define vegetation type of fen-like pine swamps, which are combinations of two peatland types, quagmire and pine swamp. Typical for this peatland type is that the vegetation is very heterogenous. Patches of different types of plant communities are found within a small area, but in a large scale, there are only few main types of plant communities. The commonly used way to use sample plots to study tree stands suit poorly to determine the type of this kind of heterogenous ground vegetation. The article compares strip survey and circular plot survey, of which circular plot survey is determined to be less time consuming. The article describes a way to choose the locations of sample points to achieve most correct areas for different plant communities.

The article includes an abstract in German.

• Heikurainen, E-mail: lh@mm.unknown

Silva Fennica issue 46 includes presentations held in professional development courses, arranged for foresters working in public administration in 1937. 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 inspection of forest regeneration of mineral soil forest types and drained peatlands, and inspection of ditches. 

• Ahola, E-mail: va@mm.unknown

Silva Fennica issue 46 includes presentations held in professional development courses, arranged for foresters working in public administration in 1937. 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 afforestation of drained peatlands. 

• Lukkala, E-mail: ol@mm.unknown

The present investigation revealed that the influence of a forest cover on the water economy of the soil is very great in Finland. Cutting of the forest gave cause to a rise of the ground water table, which, when clear-cutting is in question, reached a magnitude of 20–40 cm. The water supplies of the soil increased 40–60 mm. In the winter, too, the ground water remaind at a lower level in the forest than in opening, however, the difference is rather small. Thinnings had same kind of effect as clear-cuttings, but the influence of even heavy thinnings was still relatively small.

The water supplies of the soil after felling decreased mainly due to the decrease in the interception in the canopy. When the water table is at the same level in the forest and in opening, evapotranspiration might be greater in the forest than in openings. However, when the water level is during the growing season considerably lower in the forest than in an opening, the evapotranspiration is strongly decreased in the forest, which means that more water is evaporated and transpirated from the opening than from the forest. Because the water table is at a higher level in the opening than in the forest, runoff from clear-cut areas has exceeded that from the forest. This means that the influence of felling on the water economy of the soil is actually even greater than indicated in this work.

The results mean that the influence of the forest cover makes up that of drainage. This affects the need for maintenance of ditches. On the other hand, the final cutting will rise the ground water strongly.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The determination of biologically most favourable strip width in peatlands to be drained has been hindered by lack of information of the temperature conditions in the surface peat and in the air close to the ground after drainage of different intensities. Temperature measurements were carried out on peatlands drained to different degrees in Central Finland in the summers of 1960 and 1961. The ground water level in the measuring points, and the strip width served as the criterion for differences in water condition.

When the drainage became more intensive, the temperature of the surface peat decreased. However, temperature differences were small, and discernible only when the differences of water conditions were considerable. The effect of strip condition to temperature seems to be of similar nature than the ground water level. Even in extreme cases temperature differences due to different drainage intensity were relatively small, and seldom exceeded 2°C.

Differences in temperature dependent on the growing stock may be as high as 10°C. Thus, the temperature of the surface peat may be dependent on factors more important than temperature differences caused by aspects of drainage. A well-drained peatland is coldest at the beginning of a growing season compared with poorly drained peatland. The temperature differences increase deeper in the peat. This is caused by the better heat conductivity of the moist peat. Also, daily variations in temperature in the surface peat are large in moist peat.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

Decomposition of the peat using von Post Humification Scale (1–10), developed by Lennart von Post, can be determined based on characteristics of peat, such as fibre integrity, colour and viscosity of exudate, and presence of colloidal particles, of handful of peat squeezed in the hand. It is easy to use and has proved useful in the practical work. The method developed by Pjavthenko is mostly based on specific weight off a dried sample in percentage, and requires analysis in the laboratory. The aim of this study was to compare the results of these two methods by measuring 156 peat samples representing different stages of decomposition.

The methods are based on different principles, which is reflected in small differences of the results. The maximum scores of the methods are clearly in different level. The maximum grade of 9–10 in von Post scale correspond decomposition percentage 51 in the scale of Pjavtsheko. However, the decomposition values in von Post scale are placed evenly on the scale of Pjavtshenko. This suggests that the von Post Scale is consistent and accurately developed. According to the study, the Pjavtshenko method is a good method to validate results of von Post Humification Scale, and can be used when decomposition of peat samples is determined in laboratory.

The PDF includes a summary in German.

• Sarasto, E-mail: js@mm.unknown

Since Finnish professor A.K. Cajander published his theory on forest types, there have been discussion and contradictory studies on certain forest types. This paper is a litterature review on the thick-moss type in Northern Finland and its parallel types in Kainuu and Southern Finland. First, the principles of Cajander’s theory on forest types is described and discussed. It is concluded that Cajander has described forest site types as their common, genuine variants. Borderline variants have been excluded from the description. 

Second, the North Finnish thick-moss type (Hylocomnium-Myrtillus type, HMT) and its position in Cajander’s system is discussed. Concepts of this forest type have varied considerably, and it has been argued that the type does not fit Cajander’s system very well, as it arises as a result of the invasion of other forest types by Norway spruce (Picea abies (L.) Karst.) with consequent degeneration of the site.  

The writer concludes findings of the results of the previous studies about MHT and its relations to the Myrtillus type. Cajander in his system included the thick-moss type in the moist upland forests as a type whose vegetation is less exacting than that of the Myrtillus type. This position seems to be the right one. Some factors point out the moist nature of HMT: the ability of Norway spruce to compete, a relatively high persipitation, the humidity of the climate in general and the rather poor water percolation capacity of the moraine soil. The HMT sites are relatively poor. It is stated that the opinion that the thick-moss type is secondary state of development of the Myrtillus type has no plant sociological, ecological, mensurational or silvicultural foundation. The type is probably Finland's most dynamic forest type, but in the natural forest its dynamics are confined to such changes as are permitted within the same forest type. HMT must be described as three series of plant association types, which differ from another to some extent. 

The PDF includes a summary in English. 

• Keltikangas, E-mail: vk@mm.unknown

Prescribed burning has been used to treat the mineral soil sites, but the method has been little used in drained peatlands. The course and methods of prescribed burning in drained peatlands, and the effect of burning on sprouting of broadleaved trees, growth of ground vegetation and regeneration of Scots pine (Pinus sylvestris L.) by sowing was studied in drained pine bogs in Southern Finland. The top layer of the peat was mostly Sphagnum peat. The material included a prescribed burned 12 ha drained peatland area in Tuomarniemi district, in addition to which ten previously burned areas were investigated.

The burning had succeeded mostly well, but also unsuccessfully burned sites were observed. Estinguishing of the fire was easy, and no peat fires occurred. The fire burned only the logging residue, ground vegetation and the dry top layer of the peat. The roots of brushwood and grasses survived in the peat that insulated the top layer from the heat. For instance, the abundance of cloudberry (Rubus chamaemorus L.) increased after the fire. Similarly, burning did not affect sprouting of the stumps of downy birch (Betula pubescens Ehrh.). It cannot thus be used as a method to restrict the growth of coppice in regenerated areas. The seeds of Scots pine germinated well on the burned surface. 46% of the seeds developed to seedlings on sphagnum-shrub vegetation and 16% in feathermoss-shrub vegetation.

The PDF includes a summary in German.

• Yli-Vakkuri, E-mail: py@mm.unknown

According to studies following the development of vegetation of drained peatlands, it seems that they have transformed to a relatively stable plant communities during the succession. In earlier studies it was assumed that after drainage a mire type would develop to a corresponding forest site. This investigation studies what kinds of plant communities are formed during succession of different mire types on peatlands drained for forestry in the southern half of Finland. Understorey vegetation was studied in 18 sample plots established by Forest Research Institute on drained peatlands. In addition, sample plots were studied on peatlands in natural state.

The results suggest that understorey vegetation on peatlands drained for forestry have developed into plant communities, the most advanced of which are the so-called dry plant communities. They represent transformed site types, which are the following: drained peatlands with upland herb-rich vegetation, drained peatlands with upland grass-herb vegetation, drained peatlands with upland Myrtillus site type vegetation, drained peatlands with upland Vaccinium site type vegetation, and drained peatlands with upland Calluna site type vegetation. Drained peatlands with upland Cladonia site type vegetation seem to be a temporary type caused by incomplete drainage. The transition between Myrtillus and Vaccinium dominated dry plant communities is not clear, but especially the pure Vaccinium vitis-ideae communities justify its place as an independent plant community. The dry drwarf shrub plant communities are also stable.

The PDF includes a summary in German.

• Sarasto, E-mail: js@mm.unknown

The article deals with forest ditches dug by manual labour in drained peatlands in Central and Southern Finland, ranging in age from 16 to 25 years. The ditches have been allowed to develop in a natural state. A total 1,160 of randomly selected sample plots were studied.

The results show that the originally dug ditch depth has not been the decisive factor from the viewpoint of maintaining the ditch repair. Ditches dug in thick peat layer have maintained their repair better than those dug in thin peat layer. Apparently, the influencing factor is the type of soil, to a certain extent parallel to the thickness of peat layer. In ditches dug mainly in mineral soil, the type of soil has essentially contributed to maintaining the ditch repair. Ditches in coarse-grained soils maintained a better repair than those in fine-grained soils. Also, the steeper the gradient of the ditch the better the ditch repair has been maintained. There was no relationship between the thickness of peat and the filling up of ditch bottom, because of the influence of mineral soil. Filling up of a ditch seems to be mainly due to the sinking of peat. The filling up of ditch bottom was more pronounced in clay-silt soil than in other soil types. The filling up of ditch bottom by varying gradient is due to the fact that with a small gradient the speed of water is so slow as to permit the soil particles to sink to the bottom. Another factor affecting filling up of the ditches is wetness of the peatland. Deepening of ditches happens mainly through erosion, if the gradient is large enough. The study suggests that a 50-m spacing with about 60-cm ditchc depth would be most profitable.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

Pine swamps are easily regenerated by natural regeneration of Scots pine (Pinus sylvestris L.). Usually seeding felling is used, but also strip system or clear cutting and regeneration along stand edge has been suggested. This article discusses the regeneration by clear cutting and sparing the existing undergrowth. The article focuses on pine swamps to be drained and the ones in natural state.

Pine swamps in natural state usually have plenty of trees of smaller diameter classes, that can be trusted to form the future tree generation after the felling. This shortens the rotation by 20-30 years. The undergrowth has been shown to recover quickly. The method suits for regeneration of drained peatlands but could fit also for regeneration of pine swamps in natural state.

The seedlings in the pine swamps are mainly 1-5 years old, and the stock is changing. It seems that larger trees produce a wider selection of age groups, but the seedlings survive longer under smaller mother trees. Part of the younger generations of seedlings seem to be destroyed when the peatland is drained. Further studies are needed to investigate how the draining and felling are to be performed to spare the young seedlings.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

The PDF includes a summary in German.

• Heikurainen, E-mail: lh@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 article introduces methods that can be used to calculate economic profitability of draining of peatlands, and discusses their advantages and weaknesses. The time span from draining of a peatland and the future income is usually decades, which makes it difficult to assess profitability for the investment. For instance, income from future fellings depends on chosen rotation time, and price of timber that can fluctuate strongly.

When calculating the profitability, the drained area can be treated as a separate unit of account or as a part of the forest holding. In the first case, several methods can be used. First, yield in terms of value is a suitable method only if the peatland has no existing forest. Second, annual yield of a drained peatland and peatland in natural state can be compared. In this case yield can be defined in several ways. Third method uses value increment of the growing stock. Fourth method estimates value of increment for both the growing stock and land. Fifth method is based on present value of the future felling income, and sixth on actual value of the growing stock and yield in terms of value.

The PDF includes a summary in German.

• Saari, E-mail: es@mm.unknown

The relation between the occurrence of forest site types and swamp types was studied using data collected in the national line survey of Finnish forests carried out in 1921‒1924. The majority of peatlands in Finland has been formed by forest land becoming paludificated. When the peat layer is thin, the fertility of the peatland depends on the underlying mineral soil, consequently, good swamp types occur on fertile subsoil and poor types on poor subsoil. When the peat layer becomes thicker, the relationship weakens. The surrounding mineral soils influence the quality of the peatland by the runoff from the catchment area. The direct comparison of forest site and swamp types is not possible, because for one forest site type there are several swamp types that have different levels of humidity. According to the study, a very distinct mutual relation can be seen between occurrence of forest site types and swamp types.

The PDF includes a summary in English.

• Ilvessalo, E-mail: yi@mm.unknown

The vegetation of the forest and peatland site types in Northern Finland differ markedly from those in Southern Finland, also the vegetation of the subtypes in the north is distinctive. A line survey was conducted to study the distribution of forest and peatland site subtypes in Northern Finland.

The vegetation of rich grass-herb forest types differs little from the poorer grass-herb forest types in Northern Finland. They abundance decrease towards north. The main fresh mineral soil sites are Myrtillus site type, Hylocomnium-Myrtillus site type and their paludified forms. The abundance of the fresh mineral soil sites decreased towards north so that in Kemi the proportion was 20.5 and in Lapland 12.0%. A transition from the fresh to the drier site types is gradual. The Vaccinium site type that is dominant in the south, is rare in the north, where it is replaced by Empetrum-Vaccinium type. The proportion of dry forest sites increase towards north, in average their distribution is 25% of the lands. There are numerous subtypes, which can be merged in to four main site types: Calluna, Cladina-Calluna, Myrtillus-Cladina and Cladina site type. The peatlands are more abundant in the southern part of the study area. The most common peatland types are pine swamps.

The PDF includes a summary in German.

• Multamäki, E-mail: sm@mm.unknown

• Kujala, E-mail: vk@mm.unknown

Peatlands amount to more than a third of the land area of Finland. The article includes a review on the peatland complexes and types, their distribution in Finland and how different peatland types suit for draining. Finnish peatlands have typically relatively shallow peat layer, which influences how they suit for agricultural lands or forestry.  Systematic draining of peatlands has been practiced since 1908 in the state forests. In 1908-1919 Metsähallitus (Forest Service) drained slightly over 200,000 hectares of peatlands, and the forest companies are estimated to have drained about similar area. An estimate of how big proportion of the peatlands would be worth draining is deduced, based on existing statistics of the state lands, and on a line survey. In the state lands 35% of the peatlands, about 2 million hectares, are worth draining. If an estimate of the figures of private lands is added, of the total of 5 million hectares of peatlands in Finland about 54% is suitable for draining.

The PDF includes a summary in German.

• Multamäki, E-mail: sm@mm.unknown

An extensive field-based survey was conducted to establish the distribution of site types on drained peatlands, the condition of the drainage networks, the post-drainage development of the tree stands, their structure and silvicultural condition and the corresponding requirements for operational measures. The data is based on sampling of the forest drainage undertaking during 1930–78 and consists of 1,312 km inventory transect, 6,030 relascope sample plots and 21,700 studied ditches.

Of the studied peatlands more than 60% were Scots pine (Pinus sylvestris L.) mires, slightly under 20% Norway spruce (Picea abies) mires, and under 10% each treeless mires and paludified upland forest sites. The remaining peatland area that is to be considered suitable for forest drainage according to criteria used by Heikurainen (1960) now consists mainly of spruce mires and paludified upland forest types; about 1 million ha both groups still remain undrained.

The proportion of ditches in need of ditch cleaning was estimated to be under 10% in the youngest drained areas and under 30% in the oldest. The mean tree stand volumes of the drained peatlands of different site types show the same dependence on the trophic level as in earlier studies but the volumes seem to be some 5–10% lower. These results compare favourably with those of the 7th national forest inventory.

Trends in the post-drainage development of tree stand volumes and increment are also, generally, in accordance with earlier findings but have somewhat lower values. The development of the nutrient-poor site type stands, especially in Northern Finland, seems to be significantly poorer than was earlier assumed.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown
• Laine, E-mail: jl@mm.unknown
• Puttonen, E-mail: pp@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The possibilities of using microwave techniques in detecting the trafficability of peatlands is discussed. Three microwave methods were tested. 1) A FM-CW radar using 1.0–1.8 GHz frequency was used to measure the frost thickness of peat layer. It was possible to follow the variations in snow and frost layer thickness. Total reflected power might indicate the wetness class of the peatland, which is also a trafficability factor. 2) A short-pulse radar with 100 MHz frequency was tested in summer condition. Good profiling of peat layers was obtained, giving basic information for trafficability analysis. 3) A mapping of brightness of temperature of peatlands in summer conditions using a 790 MHz radiometer. The measured brightness temperature was correlated with vegetation cover, thus giving some information of trafficability.

The PDF includes a summary in English.

• Saarilahti, E-mail: ms@mm.unknown

The aim of this investigation was to examine the dependence of stand volume and increment on different growth factors on drained peatlands drained 20 years ago. Measurements were made in 1977-79 on 35 sample plots in Central Finland on relatively poor pine bogs with a thick peat layer.

It became evident that the stand volume, increment and radial growth and growth development are primarily functions of groundwater depth. Groundwater depth is dependent, in the first place, on ditch depth and ditch condition. With regard to the variation in ditch spacing (ca. 35-70 m) under examination, the effect of ditch spacing on the stand was insignificant. As a practical recommendation it was concluded that ditches should be kept deep enough (> 70 cm) in order to maintain undisturbed stand development.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The Oulanka National Park is situated in the district of Kuusamo on the eastern border of Finland, close to the Arctic Circle and within the coniferous forest zone. It covers a surface area of 107 km², and is known for the richness of its vegetation and flora, a product of a varied bedrock pattern including occurrences of dolomite. A description is given of the vegetation of the 9 forest and 47 peatland types distinguishable in the area by means of tables based on quadrat surveys. The distribution of each forest and peatland type is described in a vegetation map. The vegetation types are discussed in terms of the structure of their soil and the ecological and floristic features of their plant cover.

The PDF includes a summary in English.

• Söyrinki, E-mail: ns@mm.unknown
• Salmela, E-mail: rs@mm.unknown
• Suvanto, E-mail: js@mm.unknown

The paper presents some preliminary results of a 10-year-old study the purpose of which is to determine the effect of simultaneous variations in the intensity of drainage and fertilization on the development of planted and natural seedlings on peatlands under various climatic conditions. The development of the Scots pine (Pinus sylvestris L.) seedlings appeared to be better the more intensive the degree of drainage and fertilization used. The increase in the temperature sum had a positive effect on the development of pine seedlings and decreased the mortality rate.

The best growth result was obtained with a 10 m ditch spacing and strong fertilization. As it is difficult to decrease the 10 m ditch spacing for cost reasons, it can be concluded that on such oligotrophic peatlands as were used in this experiment, only an average growth level in the seedling stands can be reached even with the most efficient forest improvement measures. Broadcast fertilization used in the experiment, at least in large doses, increases seedling mortality, as well as the coverage of the ground vegetation, particularly that of cottongrass and fireweed, and also the shrub height, thus increasing competition. It cannot be recommended for afforestation, and today spot fertilization is used. According to this experiment natural seedlings seem once they have recovered after the first years, to grow better than the planted seedlings. This was true especially in the north and in areas, where drainage was not efficient. The height and height growth of the seedlings were to a large extent dependent on the temperature sum.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Laine, E-mail: jl@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

In Finland The Central Forestry Board Tapio conducts forest drainage operations on swamps owned mainly by private individuals. This drainage is almost totally financed by the Government either as loans or subsidies. The local contractors have left bids about new forest drainage projects, and the best bid has won the contract. The trend of the average price for forest drains has been declining during the last 11 years although digging costs have increased. The aim of this study was (1) to explain the regional price variation of forest drains made by tractor-diggers and (2) to describe competition among tractor-digger contractors and to measure its effect on prices.

Correlation and regression analyses support the hypothesis that competition among tractor-digger contractors has decreased forest drain prices, especially in 1967. In the course of the last two years this competition effect has been lessening. The most significant other variables explaining price variations were the proportion of winter drainage, length of drainage work done for each participant in the project, and density of drains.

The PDF includes a summary in English.

• Palo, E-mail: mp@mm.unknown

The aim of the study was to determine how the spacing of drains affects the economic results of forest drainage projects. On the basis of empirical material consisting of 411 sample plots, it is presented marginal cost curves showing how many meters more of drains it is needed to increase the value of stock, 35 years after the drainage, by a value equivalent of one cu.m of coniferous pulpwood. Results indicate that wider spacings ought to be used on poor sites, on sloping swamps, and in the north.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown

In 1965 and 1966 a total of 25 experiments were laid out in various parts of Finland in order to find out the effect of simultaneous variation in the intensity of drainage and fertilization on the development of plantations and natural seedling stands of Scots pine (Pinus sylvestris L.) growing on pine swamps. The fertilizer used was Y fertilizer for peat soils, a fertilizer mixture containing 14 % N, 18 % P₂O₅ and 10 % K₂O. It was applied in rates of 500, 1,000 and 1,500 kg/ha. The ditch spacings studied were 10, 20 and 30 m. The present paper is a preliminary report on a series of studies, the experiments will be observation for a total of 15–20 years.

Mortality of the planted seedlings was found to be the higher after the first growing season, the larger the quantity of fertilizer that had been applied. Fertilizing caused an increase in seedling mortality even after the first growing season following application. At the end of the fifth growing season the height of both natural and planted seedlings is the greater, the larger the quantity of fertilizer that has been applied. Analysis of the height growth of the seedlings showed that larger quantities of fertilizer did not increase growth in the same proportion. The occurrence of growth disturbances is the greater, the more fertilizer has been applied.

Fertilization also changed the composition of ground vegetation. The in the beginning of the experiment  birch (Betula sp.) was absent in the area, but was found in the stands the greater abundance the higher application of the fertilizer.

From the viewpoint of growth of the seedlings the best results were obtained with the greatest intensity of fertilization and the narrowest ditch spacing used in the study. The results also show that strong fertilization and a high degree of drainage intensity are not capable of bringing about any particularly good growth on peatlands which originally are relatively poor in nutrients. The growth values now obtained equal only one third of those obtained on peat soils of greater fertility.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown
• Veijola, E-mail: pv@mm.unknown

The present study deals with the ground water table in the soil of drained peatlands and with the technique used for its determination. The terms depth and height of the ground water table are defined in the paper. Because of the fact that the surface of peatlands moves under the influence of a great number of different factors, the depth of the ground water table and the height of the ground water table are not parallel concepts. The present paper concentrates on the depth of the ground water table.

Observations on the depth of the ground water table in the sample plots in 1966-67 and 1968-69 show that the maximum of the late summer usually exceeds that of the early spring, and that the minimum occurring in the period of snow melting is more clearly discernible than that of the fall. Great differences occur in the depths of the ground water table in different sample plots. These differences are due to the specific properties of the peat of different peat layers, which are expressed in terms of the ground water coefficient. The duration of the depth of the ground water table proved to be a useful way to express the long-term changes.

Four kinds of short-term fluctuations in the ground water table were observed: a) the ground water table falls during the night hours, although the rate of falling is slower than in daytime, b) the ground water table rests at the same depth during the night, whereas during the day it clearly falls, c) the descent of the ground water table is similar throughout the whole 24-hour period, d) the ground water table rises during the night hours and falls in daytime. Occurrence of these types are discussed. Typical short-term fluctuation is the fall due to evaporation in the daytime.

The third part of the paper discusses the techniques used to measure the changes in ground water table.

The PDF includes a summary in English.

• Heikurainen, E-mail: lh@mm.unknown

The present study is an attempt to establish the response to drainage of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) on some peatland sites, and to determine the revival of the trees and continuance of the growth after drainage. Growth of trees in four types of peatland types of drained peatlands drained between 1908-1918 were studied, and the results were compared with corresponding mineral soil sites

In pine the response to drainage was faster than in spruce in all age classes. Even the oldest groups of trees showed as good growth as trees of the same size growing on mineral soils. The rapidity of revival and the radial growth maximum are affected by the age of the tree at the time of ditching and the site fertility. The size of the trees, too, is of importance for the magnitude of post-drainage radial growth; the influence is similar in different sites. The basal area growth of trees growing on peat usually showed an unbroken increase during the entire post-drainage period. Neither the height growth indicates a decline in growth over time.

In the light of the results from sample tree analysis, it seems that tree growth gradually rises even after the revival period in peatlands originally covered by forest. The are some errors in the comparisons made, but it can be observed that aging of drainage areas as such does not mean that growth conditions become poorer.

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• Seppälä, E-mail: ks@mm.unknown