Current issue: 58(5)
Articles containing the keyword 'draining'
Category : Article
The present study deals with the effect of forest drainage on some quality factors of brook waters. Under study were several brooks in the basin of the Kiiminkijoki River as well as its main tributary, the Nuorittajoki River. These are located in Northern Finland and belong to the international water program Project Aqua.
The following values were determined for the water samples: pH, electric conductivity, colour, concentration of suspended solids., NO2, NO3, and NH4 nitrogen concentrations, dissolved and total phosphorus, and Ca, Mg, K and Fe concentrations. Water quality in the brooks was monitored prior to and after ditching. A statistically significant change was noted in colour, in the concentration of suspended solids, in the NH4 concentration and in some brooks also in the pH value and in the total phosphorus, K, and Fe concentrations.
The PDF includes a summary in English.
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Hynninen,
E-mail:
ph@mm.unknown
- Sepponen, E-mail: ps@mm.unknown
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.
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Heikurainen,
E-mail:
lh@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.
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Timonen,
E-mail:
et@mm.unknown
The study attempts to establish to what extent the present regional allocation of the forest improvement subsidies equalize the profitability of forest drainage in Finland. The benefit/cost ratio has been used to describe the regional variation of the profitability
The study revealed that the forest improvement subsidies granted in 1968, even the highest possible subsidies, did not equalize the profitability of forest drainage. According to the results, the northern regions are at a disadvantage compared to the southern parts of the country. To fully equalize the profitability of forest drainage the average subsidies granted in 1968 should have been raised in the second financing zone from 22 to 32%, in the third zone from 32 to 60%, and in the fourth, northernmost zone from 43 to 86%. The study also suggests that the boundary lines of the financing zones should run, at least in Central and Northern Finland, from southeast to northwest instead from east to west, as it is now.
The PDF includes a summary in English.
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Numminen,
E-mail:
jn@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.
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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.
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Heikurainen,
E-mail:
lh@mm.unknown
Silva Fennica Issue 80 includes presentations held in 1952 in the 7th professional development courses, arranged for foresters 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.
This presentation describes the factors that limit growth of trees in peatlands, and principles of draining of peatlands.
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Mansner,
E-mail:
pm@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.
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Huikari,
E-mail:
oh@mm.unknown
Silva Fennica issue 42 includes presentations held in professional development courses, arranged for foresters working in public administration in 1936. 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 the effects of draining of peatlands on water management in the peatland and the surrounding area.
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Metsänheimo,
E-mail:
um@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.
This presentation discusses the use of peatlands in agriculture and peatlands' suitability to farming.
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Kotilainen,
E-mail:
mk@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.
This presentation gives guidelines for draining of peatlands.
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Cautón,
E-mail:
ac@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.
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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.
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Lukkala,
E-mail:
ol@mm.unknown
Draining of peatlands requires careful planning because of its costs. Only peatlands that have sufficient growth capacity in future should be drained. The future growth capacity can be estimated based on peatland type, the botanical composition of the peat layers and the quality of the surface peat layer of the swamp.
Also the draining methods should be cost effective. To keep the amount of drains low, the drain network and drain lines should be planned so that each drain has high drain effectivity. Most of the peatlands drained in Finland have been forested. Especially the young trees regain soon their growth when the peat begins to dry. It is recommended to leave the young trees, but most profitable to harvest the older forests in the drained area. Practical experiences have shown that even drained open peatlands can be naturally regenerated. Natural regeneration is almost guaranteed to succeed on peatlands, which have seed trees.
A summary in Finnish is included in the PDF.
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Lukkala,
E-mail:
ol@mm.unknown
Category : Article
The Finnish forest industry is undergoing a vast expansion, which has raised questions of forest balance. This paper studies the possibilities to increase the amount available timber by means of forest drainage. About third of the Finnish land area is peatlands. The calculations of the investigation are based on Forestry Board districts. Based on earlier studies, there is estimated to be 3,042,000 ha of true drainable swamps, 973,000 ha of poor swamps, 1,381,000 ha of uplands in need of drainage, and 1,205,000 ha of drained peatlands. Therefore, the area of drainable and drained lands totals 6,6 million ha, and requirement of forest drainage 5,4 million ha. The drainage hardly reaches this extent, however. It can be assumed that part of the poor swamps is uneconomical to drain. In addition, a half of the paludified forest land will probably not be drained. Thus, it can be estimated that the area to be drained in the future is about 5 million ha. It seems possible that this area could be drained within about 50 years with the present draining capacity.
Draining of all objects of forests would increase the annual increment of our forests, in time, by about 10.5 million m3. This would signify an increase of 23% compared to the present growth of the forests. The increase in the growth consists mainly of softwood: 16% is birch, and the remaining 84% almost equally of Scots pine and Norway spruce. The increase of growth is relatively slow. Depending on the rate of the drainage program, the mean increase of growth will be reached in about 25–35 years. The increase in removal indicated by the increase in the mean increment will be reached in only 50–60 years.
The PDF includes a summary in English.
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Heikurainen,
E-mail:
lh@mm.unknown
Draining transforms root systems of trees growing in peatlands towards the ones growing on mineral soil. However, even after efficient draining the root systems differ from the root systems of trees growing on mineral soil. This investigation concentrates on root systems of forests of similar mire types growing in similar draining conditions but having different tree species compositions. The peatland, situated in Pieksämäki in Southern Finland, was drained in 1937. Sample plots, measured in 1956, consisted of mixed forest of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and birch (Betula sp.) in different compositions, and were in natural condition.
The sedge pine bog studied in this investigation was shown to have larger total amount of roots and mycorrhiza than in previously studied dwarf shrub pine bogs. This reflects better growth conditions of the better site. The depth of root system was, however, similar. Root systems of birch were deeper than those of the coniferous tree species. Differences between Scots pine and Norway spruce were small. Corresponding differences between the species were found in the density and total number of mycorrhizas. The abundance of mycorrhizas in the roots of birch increased in deeper layers of peat, but decreased especially in spruce roots. In earlier studies the abundance of mycorrhizas decreased in the roots growing in deeper layers in pure Scots pine stands, but no such variation was seen in this study. The result suggest that the deep root system of birch may affect also the root systems of the coniferous trees. On the other hand, birch roots can have advantage over the coniferous trees.
The PDF includes a summary in German.
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Heikurainen,
E-mail:
lh@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.
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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.
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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.
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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.
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Saari,
E-mail:
es@mm.unknown
Approximately 320,000 hectares of peatlands and paludified lands had been drained for agriculture and forestry purposes in Finland by 1920. The ditch network was not optimal in the early drained areas, and the condition of the ditches declined over time. In this study, the condition of drainage system, and the natural processes that affect them, was inspected in 18 drained peatlands.
Several processes can reduce of the size of the ditches. The process of crumbling of soil in the sides of the diches can last up to three years after the draining. Erosion of the main drains, caused by water flow can, however, continue longer. The ditches also sink when the peat dries. Soil frost can affect the ditches, but as the vegetation grows its effect gradually decreases. The vegetation that grows in the ditches may finally block the ditch completely.
The PDF includes a summary in English.
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Kokkonen,
E-mail:
pk@mm.unknown
Only about 24,000 hectares of peatlands have been drained in the state lands by the 1921. The aim of this study was to define how much the growth of the trees in the drained peatland revives. Sample plots were measured in previously drained peatlands that had sufficient Scots pine (Pinus sylvestris L.) tree stand. A stem analysis was performed to one of the sample trees. The evenness of the stands was dependent on how evenly the peatlands had dried when the stand was regenerated. Thus, the sample stands were not always fully stocked. However, they had capacity to develop towards evenly structured forests as the peatlands continued to dry further. The diameter and height growth of the dried peatlands have corresponded the similar stands in mineral soil sites. In trees that have grown stunted in the peatlands, the diameter growth seems to increase faster than the height growth. The volume growth is slightly smaller than in the similar mineral soil sites due to less favorable stem form. After the draining, the roots of the trees continued to grow from the old branches of root, but start then to form new roots. When the ground water level drops, the root layer grows deeper.
The PDF includes a summary in German.
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Multamäki,
E-mail:
sm@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.
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Multamäki,
E-mail:
sm@mm.unknown
Draining of peatlands to improve forest growth started to increase in Finland in the beginning of 1900s. The aim of the study was to find out which kind of peatlands are suitable for draining. The peatlands examined in this study had been drained earlier in 1800s for other purposes, and the original peatland type was deduced afterwards. When the peatland is drained, its vegetation changes gradually towards that of mineral soil sites, depending on the original peatland type. The article includes detailed description of the vegetation on different drained peatland sites. Best represented in the study were different types of pine swamps, which change towards Calluna or Vaccinium forest site type depending on the original peatland type. The Sphangnum species and brushwood disappear gradually and Cladina sp. become common in some drained pine swamp types. Scots pine (Pinus sylvestris L.) regenerates well on most drained pine swamps, and also Betula sp may grow as dominant species. The richer pine swamp types develop to Vaccinium-myrtillus forest site type, which may grow also Norway spruce (Picea abies (L.) H. Karst). Drained treeless bogs change first towards pine swamps. However, trees regenerate poorly on these sites and the growth is low. Flark-bogs develop typically to treeless lichen heaths. Drained spruce swamps develop to forest with grass-herb vegetation or Myrtillus site type.
The PDF includes a summary in German.
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Tanttu,
E-mail:
at@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.
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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.
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Palo,
E-mail:
mp@mm.unknown
The paper is based on data collected from 411 sample plots in various parts of Finland situated on peatlands which had been drained in the 1930's. The purpose of the study was to determine the influence of ditch spacing on the volume, increment and structure of timber crops growing on drained peatlands. The ditches had been spaced 70–90 m apart, and the sample plots were placed strip wise along the ditches.
The results of the study indicate that the influence of ditch spacing on both the total volume and the volume increment is greater, the poorer the site. On the other hand, the influence of ditch spacing on the structure of the stand as described by means of the mean diameter as weighted by the basal area, seems to be of similar magnitude in all the sites covered by the study.
Generally speaking, the influence of ditch spacing on stand development is surprisingly small, even in extreme cases. The total volume and the increment of the growing stock decrease by about 20% when the ditch spacing increases from 20 to 60 m, the corresponding decrease in the mean diameter having a magnitude of 10%. This was interpreted to be due to the fact that the main part of the superior growth along the margin of the ditch is spent in compensating for the space lost in the area taken up by the ditches.
On the basis of the results obtained it was concluded that the best solution in forest drainage from the economic viewpoint is to employ relatively wide ditch spacings, which leads to a rate of stand development somewhat below the potential.
The PDF includes a summary in Finnish.
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Seppälä,
E-mail:
ks@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.
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Keltikangas,
E-mail:
mk@mm.unknown
