Suo - Mires and peat 27 (1976)

The results of plant coverage analyses carried out in summer 1976 on a peatland drained in 1950 are presented in this article. The results from earlier analyses (1950, -52, -54, -59, -63 and -70) have earlier been published (Mannerkoski 1970). The tree stand characteristics measured in 1961, -66 and -73 are also presented (Table 1). The results for the plant coverage analyses (Table 2, Fig. 2 and 3) have been obtained from five plant coverage sample plots. The tree stand consists mainly of Scots pine and has grown well. The mean stand increment during the period 1966—73 was 5.8 (A26) and 4.0 (A28) m3/ha/yr calculated as the difference between the volumes with bark. There was a lot of Norway spruce and birch seedlings growing in the stand but only few pine seedlings were found (Fig. 1). The most important changes which had taken place in the coverage of different plant species since 1970 were as follows: Dicranum had increased and Sphagnum recurvum had decreased on plots 1—3, Sphagnum robustum had increased on plots 3 and 4 and Vaccinium oxycoccos had decreased on all the plots. Aulacomnium palustre, Eriophorum vaginatum and Carex canescens had completely died out. It can be clearly seen from figures 2 and 3 that the increase in Vaccinium vitisidaea has stabilised and that Polytrichum commune is still present in large numbers. It appears that the changes in the coverage of different plant species are dependant on the effect of shading and competition by the tree stand. Only those species with the greatest moisture requirements have disappeared within the first few years after draining as a result of drying out of the surface peat (cf. Mannerkoski 1970).

• Mannerkoski, Sähköposti: ei.tietoa@nn.oo

This paper presents the results of heavy metal (trace element) analyses of plant samples collected from three undrained ombrotrophic bogs in southern Finland (60—61°N, Fig. 1). The species studied included three mosses — Sphagnum fuscum, S. balticum, S. majus — and four lichens — Cladonia stellaris (= C. alpestris), C. arbuscula, C. rangiferina, Hypogymnia (= Parmelia) physodes. Also the needles of stunted bog pines Pinus silvestris) were collected and separated according to age (current vs. 1—2-year-old needles). Collective samples (5—10 replicates) consisting only of the living top part were taken (lichens 4—5 cm, hollow mosses 3—6 cm, hummock mosses 2 cm). The samples were dry-ashed at + 500° C, then dissolved with cone, hydrochloric acid, diluted with distilled water and analysed for metals with Varian Techtron AA-1200 atomic absorption spectrophotometer at Botany Dept., University of Helsinki. Duplicate samples were also digested directly with HNO3 and HCl for control. The results of the former method are presented in Figs. 2—4 on oven-dry ( + 70°C) weight basis. Among bryophytes, the contents of Pb, Zn and Mn were in all cases highest in hummock species Sphagnum fuscum and lowest in the wet-hollow species S. majus. Among lichen species, the concentrations of lead and zinc decrease in the order: Hypogymnia physodes (epiphyte) > Cladonia rangiferina > C. stellaris, C. arbuscula. In Pinus the needles from the current year contain less metals than the needles from previous years. A comparison of different plant groups depends upon the element analysed (see Figs. 2—4). Mn content is highest in pine needles followed by Sphagnum fuscum and lowest in lichens and hollow mosses. Zn content is greatest in the epiphytic lichen Hypogymnia followed by pine needles, then by bog mosses and reindeer lichens. As opposed to zinc, the content of lead is lowest in pine needles which fact suggests a low absorption capacity of atmospheric heavy metals by pine needles. On the other hand, zinc and manganese seem to be actively translocated by pine. Consequently, needle analysis does not appear to be an appropriate method for monitoring the deposition of heavy metals. Both lichens and mosses (with the exception of hollow species), however, seem to be efficient accumulators of zinc and lead at least. If the annual primary production of mosses can be determined, it becomes possible also to estimate the deposition rate per surface area of some heavy metals.

• Pakarinen, Sähköposti: ei.tietoa@nn.oo
• Mäkinen, Sähköposti: ei.tietoa@nn.oo

Observations are presented from an excursion made by the authors in 1973 to the peatlands in the vicinity of Heart Lake, located 40 to 50 km west of the city of Hay River in the Mackenzie District, N.W.T. Two mire complex types were distinguished, namely aapa-mires and raised bogs. Apparently referring to similar peat-land types, Zoltai et al. (1974) have used the terms «string fens» and «peat plateaus», respectively. The extensive aapa-mires of the study area (southwest of Great Slave Lake) have a reticulate structure, i.e. the strings (= peat ridges) form a continuous net which alternates with wet flarks (= rimpis). It is noticed that aapa-mires with similar surface pattern have been described from N. Finland just south of the palsa mire zone (Ruuhijärvi 1960). Due to the calcareous nature of bedrock, the aapa-mires in the Heart Lake area studied are strongly minerotrophic (eutrophic). Particularly the moss species, but also many vascular plants allow a comparison to the mire types in northern Finland; such homologues are for example the «Rimpibraunmoore», «Campylium stellatum -Braunmoore» and «Braunmoor-Reisermoore» described by Ruuhijärvi (1960). Special attention was paid to the plant species indicating a transition from minerotrophic (aapa-mire) to ombrotrophic (raised-bog) conditions. «Fen windows» or minerotrophic hollows (cf. Sjörs 1963) in raised-bog were characterized by Carex aquatilis and Sphagnum riparium. In the marginal parts of the raised bog, several sedge species, Equisetum spp., Betula glandulosa and Larix laricina were the last remaining indicators of minerotrophic effect. Tamarack (Larix) is relatively easy to identify also from aerial photographs and therefore it could probably be used in mapping extensively bogs and fens in the northern boreal (or subarctic) zone. Trichophorum caespitosum, Drosera anglica and Carex limosa were commonly found in the minerotrophic peatlands visited, but these species were lacking in ombrotrophic sites with comparable water level. In less continental climate — e.g. in Ontario (Sjörs 1963) or in Finland — these three species are, however, frequent components of ombrotrophic bog vegetation. It is assumed that the low nutrient content of mire water in northern continental raised bogs restricts the occurrence of many species to minerotrophic sites. The vegetation of treeless bogs in the Heart Lake area will be treated in detail in a future publication (Talbot & Pakarinen, in prep.).

• Pakarinen, Sähköposti: ei.tietoa@nn.oo
• Talbot, Sähköposti: ei.tietoa@nn.oo

The paper deals with the extent of peat-land utilization for different purposes such as forestry, agriculture, peat mining, berry picking, water reservoirs, peatland conservation, etc. It appears that in some cases it is possible to use the same peatland area for several purposes at the same time (multiple use). However, sometimes the use of a particular peatland area is so intensive that no other uses are possible. For this reason a special council for peatland research and utilization was appointed by Suoseura (Finnish Peatland Society) in the spring 1976. The task of this council is to coordinate all activities in this field.

• Päivänen, Sähköposti: ei.tietoa@nn.oo

Kirjoituksessa tarkastellaan yhteensä noin 600 kuusi- ja mäntykoepuusta suoritetun sädekasvuanalyysin perusteella, miten puiden ojitushetken läpimitta vaikuttaa niiden ojituksen jälkeiseen säde- ja pintakasvuun tapauksissa, joissa puut kuuluvat samaan rinnankorkeusikäluokkaan. Päätulokset on sädekasvun osalta esitetty kuvassa 1 ja sivun 57 asetelmassa, pinta-kasvun osalta kuvassa 2 ja sivun 58 asetelmassa. Näyttää ilmeiseltä, että samanikäisten puiden ojituksenjälkeisen sädekasvun pitkän ajan (tutkitussa tapauksessa n. 50 vuoden) keskiarvot ovat varsin riippumattomia puiden paksuudesta. Kasvun ojituksen-jälkeinen rytmi on sen sijaan eripaksuisilla puilla toisistaan poikkeava. Tutkitun aineiston edustamissa vaihtelurajoissa tietynikäis-ten puiden ojituksenjälkeinen pintakasvu on sitä suurempi, mitä paksumpia ne ovat olleet ojitushetkellä.

• Seppälä, Sähköposti: ei.tietoa@nn.oo

The first part of the study is concerned with some general aspects of the various stages of the Baltic Sea, land uplift and shore-line displacement during the period following the last glacial period. Land uplift was much faster immediately after the end of the glacial period than it is today. As a result of land uplift, regressive shoreline displacement, i.e. movement of the shore-line seawards, has prevailed along the coast of Finland during the time following the glacial period. However, in SE Finland the sea has risen during two separate periods, at a faster rate than the rate of land emergence, and so land which has earlier emerged from the sea has again been covered, i.e. transgression has taken place. The Ancylus transgression occured around 9500—9000 B.P. and was caused by the damming up of the water in the Baltic Sea basin at a level above that of the sea during the Ancylus Lake stage. Towards the end of the Ancylus Lake stage rapid regression took place as the surface of the lake subsided to the level of the Atlantic Ocean. Regression changed to transgression after the surface of the ocean had risen, due to the so-called eustatic rise, above the threshold level of the Straits of Denmark. The eustatic rise caused by melting of the glaciers produced a considerable amount of transgression in the Baltic Sea basin during the warm period which started in the Mastogloia stage and continued into the first half of the Litorina Sea stage. At the start of the Litorina Sea stage, between 7500—7000 B.P., the water in the Baltic Sea basin clearly became salty brackish water. The transgression which occured during the Litorina Sea stage extended from the coast of SW Finland as far as the Helsinki—Espoo area. Further west, however, land uplift occured at such a fast rate that shore-line movement throughout the warm period was regressive. In the latter half of the paper, a number of examples have been presented to show, how the various phenomena connected with the development phases of the Baltic Sea and shore-line movement can be seen in the peatland and lake-sediment layers. Examples of peat layers showing transgression are to be found in Hangassuo swamp, near Anjalankoski (Eronen 1976) and Bastuberg swamp, near Porvoo (Eronen 1974). The peat layer covered by the Ancylus transgression is visible in the peat profile from the former swamp. On the other hand, the sediment layer of a small lake is covered by the Litorina transgression in the Bastuberg swamp. In addition to these, a number of examples have been presented of transgression sediment layers produced by the large lakes of the Finnish Lake District. After contracting from the Baltic Sea basin, the water in the Finnish Lake District flowed towards the Gulf of Bothnia. However tilting of the lake basins caused by land uplift of varying degree resulted in transgression, especially in the southern and south-eastern parts of large lakes. Transgression of Lake Päijänne can be seen in layer series from Lahnalampi (Asikkala) (Saarnisto 1971). Transgression of Lake Saimaa has been demonstrated in bottom layer sediments from Puntusensuo (Kerimäki) (Saarnisto 1970). Transgression ceased in both of these large lakes after a new discharge channel had formed. The water from Lake Päijänne started to flow southwards in about 6000 B.P. and the water from Lake Saimaa broke through Salpausselkä II in about 5000 B.P. forming River Vuoksi.

• Eronen, Sähköposti: ei.tietoa@nn.oo

This investigation deals with the peat types, their degree of humification, acidity, water and ash contents, phosphorous, sul-fide and nitrate contents of three peat bogs Hangasneva, Puurokeidas and Suomikeidas situated in North-Satakunta, western Finland. The Sphagnum peats of Puurokeidas bog and Suomikeidas bog are less humified and have lower pH-values than the peats at Hangasneva (Tables 1—2) which contain a higher proportion of Carex residues. The ash contents of Hangasneva peats are greater than those of other bogs. The phosphorus, sulfide and nitrate contents are low. This is very typical of bogs occuring in areas where the bedrock is granite. The history of development of the investigated peat bogs has determined by pollen analysis datings. Peat accumulation started at the time of the boreal age.

• Terho, Sähköposti: ei.tietoa@nn.oo

Different kinds of waste waters can be purified by peat. The right choice of peat quality and its correct handling may be the qualification for reaching the optimum result, i.e. the use of one and the same peat quality for all kinds of purification purposes is not possible. In the present paper, the subject is confined to discussing removal of heavy metals and oils from waste waters, as we have advanced the furthest in these fields and also because peat applies most economically to the purification of relatively small and special flows of waste water. Compared with other sorbents and adsorbents, one of the greatest advantages of peat is its price per removed impurity. At the University of Sherbrooke in Canada, a process has been developed for the removal of heavy metal ions. In this process metal ions are removed in a 2 mm thick continuously moving peat filter. Prior to this phase, the pH of waste water has been changed or sodium sulphide has been added to it. By means of this test equipment, waste waters containing mercury, copper, zinc, iron and chromium have been purified, the removal percentage being from 98 to 99 %. Five units of this process have already been sold. In an investigation carried out at the Technical Research Centre of Finland, the influence of a number of variables, such as particle size, bed thickness, bed density, heat treatment, peat quality, emulsion stability, on the purification degree, oil-binding capacity, headloss and changes in the bed have been investigated. A 98 % removal was reached by means of a 0.05 ... 0.2 m thick peat bed depending on other process parameters, and the oil-binding capacity has been from 0.1 to 0.2 l oil/l peat (corresponding to about 1 ... 2 kg oil/kg peat). An initial difficulty caused by the shrinkage of the bed has been reduced by choosing a better peat quality and optimum conditions. In a peat filtering process either equipment with a fixed bed or continuously running equipment can be used. A modification of the last-mentioned piece of equipment is being developed at the Technical Research Centre of Finland. Cost estimates indicate that a peat filter is favourable alternative in many cases. Furthermore, there are cases where the purification possibility in general is concerned, e.g. many pollution cases, rather than the economical aspects. Provided the production of filtering peat can be started by some enterpriser, there is every probability that even equipment manufacturers will be found.

• Asplund, Sähköposti: ei.tietoa@nn.oo

According to results presented previously by the author (Pelkonen 1975), a high water table during the late summer and fall has a harmful effect on tree growth on peatlands drained for forestry purposes. No harmful effect seemed to be involved, when the water table was maintained close to the soil surface in spring and early summer. In this paper, more data is presented on the influence on tree growth of a high water table in spring and early summer. In addition, some points concerning practical runoff regulation are discussed. In two stands the water table was artificially maintained close to the soil surface for varying periods in the course of four summers (1972— 1975). In the pine stand, an increase in circumference growth was recorded irrespective of treatment duration (Fig. 4). However, the increase was the greater, the longer the treatment duration. In 1975, the difference between treatments of different duration became apparent during a prolonged dry period (Fig. 6). In the spruce stand, a significant decrease in growth was recorded in 1973 (Fig. 5). This was obviously due to abundant cone production in the stand during that particular year (c.f. Simpanen 1972). In the case of Norway spruce, circumference growth was not as clearly influenced by treatment duration as was Scots pine. However, even in this case the increase in circumference growth appears to be greatest on the plot with the longest treatment duration. Precipitation, depth of the water table, and cumulative circumference growth in 1975 are presented in Figure 7. It appears that no clear differences have developed between treatments of different duration in the course of the dry spell in July—August. The different response of Scots pine and Norway spruce might be due to site differences. On the basis of this experimental data, it seems probable that tree growth could be stimulated by maintaining the water table close to the soil surface in spring and early summer. In practice, the regulation of runoff from drained areas can easily be carried out by constructing peat dams in the ditches with plastic discharge tubes.

• Pelkonen, Sähköposti: ei.tietoa@nn.oo

The material used in this study consists of two peat profiles taken from the raised bog at Ylimysneva, Parkano, in south-western Finland (Fig. 1). The correlation between the results obtained from various methods of determining the degree of humification was calculated. The methods used included the humification scale according to von Post (1922), the colon-metric method of Kaila (1956), the bulk density measurements (Päivänen 1969) and the fiber content estimation of Sneddon, et. al. (1971). The negative correlation found between the humification scale according to von Post and the fiber content proved to be statistically highly significant (Fig. 2 and 3). There was a highly significant negative correlation between the fiber content and the bulk density in the case of profile II (Fig. 5) and significant negative correlation with respect to profile I (Fig. 4). The results showed that the fiber content seems to be well suited for measuring the degree of humification. The correlations found between the colorimetric method of Kaila and the other methods were relatively weak (Table 1). This is partly due to the fact that the method is not suitable for use with all the different types of peat. The correlations which were found between the humification degree according to von Post and figures for the bulk density were lower than those reported in the literature. This is very likely caused by layers of charcoal and alluvial material in the peat.

• Raitio, Sähköposti: ei.tietoa@nn.oo
• Huttunen, Sähköposti: ei.tietoa@nn.oo

In the paper, a preliminary model of the structure and function of a boreal mire ecosystem is presented. In addition, a research plan leading to the model is described. In the exploitation and management of natural resources, information about the ecosystem as a functional unit is needed, if ecological principles are to be applied. In Finland, mires (peatland ecosystems) have been subject to exceptionally severe exploitation since forest drainage and fertilization effectively started in the 1960's, However, mires represent one of the least known ecosystems. The mire ecosystem has been defined according to Ellenberg's (1973) criteria as follows. A mire is an ecosystem maintained by cool and humid local climatic conditions and a high water table, which results in deficient decomposer activity and accumulation of organic matter (peat-forming process). The most striking features in the energetics of the system are a relatively ineffective input of energy and an even more ineffective use of it. This is indicated in the metabolism of the system by an excess production of oxygen and, in addition, by losses in the carbon, mineral, and nitrogen cycles. A general model of the mire ecosystem is presented in Figure 1, which simultaneously serves as a framework for the study. The individual parts of the project are planned to be as follows: (1) environmental factors, (2) plant community and primary production, (3) secondary production, in which (3a) energy flows through herbivores, and (3b) energy flows through decomposers, (4) nutrient cycle, (5) the accumulation of peat, and (6) succession in the mire ecosystem. In (1), special attention has been paid to factors characteristic of mires, especially the factors connected with the water table. As the aim of the study is to obtain a dynamic model of a biotic phenomenon, emphasis has been put on the continuous observation of environmental factors. In (2), a graphic model (Fig. 3) has been chosen as the primary goal. Graphic models of a few peatland site types based on preliminary studies already exist. When constructing dynamic ecosystem models, the growth rhythm of the plant communities is the most important study object. Some advances in the methodological development of measuring the growth of mire plants have been achieved. For instance, the problems involved in measuring the height growth of Sphagnum mosses in field conditions have partly been solved. An application of the IRGA-technique to studying the organic matter production of the Sphagnum — dwarf shrub community is ready for use in field conditions, but the methods for combining direct measurement data with IRGA results are still inadequate. The main task in (3) is characterized by Figure 2, i.e. energy flow and material should be divided into biotic components. By using population studies, decomposition tests, and experimental respiration techniques, a more detailed quantitative model of these pathways can be constructed. Preliminary results for total decomposer activity and the role of soil animals in detritus energy flow have already been revealed. Branches (4) and (5) are very closely connected with each other and with (3b). A detailed study into the different terms which make up the accumulation equations as a function of the environmental factors has been proposed. In (6), the suitability of the mire ecosystem as a study object of stability and succession problems has been emphasized. The successio-nal stage of the ecosystem is very strongly affected by forest improvement measures. For this reason, the study of the regulation mechanisms of mire communities is important in Finland, where about 4.5 mill. ha. out of a total of 10 mill. ha. have been drained and partly fertilized so far for forestry purposes. Finally, the future of the planned research project The structure and function of mire ecosystems and the effects of forest improvement on them is discussed. The working group consisting of biologists from the Finnish Forest Research Institute (Department of Peatland Forestry) and from a number of departments at Helsinki University (Botany, Zoology, Microbiology) is waiting for the research plan, now connected with the MAB-program of Finland, to be financed. The preliminary studies are continuing on a small scale.

• Reinikainen, Sähköposti: ei.tietoa@nn.oo

The insect fauna of Finnish peatlands is considered from the ecological point of view. The article is based on the literature published in Finland and on the author's own observations on the lepidopterous fauna of peatlands. Insects play an important role in peatland ecosystems. Several families of Diptera, e.g. Culicidae, Chironomidae, Tipulidae and Tabanidae make large contributions to the total biomasses. Dipterous insects constitute the chief food source of many waders, passerines and other birds. It is suggested that peatlands would be devoid of birds if there were no insects. The characteristic microclimate of peatlands is supposed to produce a complex of ecological factors which often determines the habitat selection and geographical range of different species. In pine bogs the temperature variations are very great as a result of the weak thermal conductivity of the Sphagnum moss layer. The most extensive temperature variations occur in relatively dry pine bogs (a "continental" climate) and the least variations in fens containing large volumes of water (a "maritime"" climate). Moisture and acidity (pH) of the moss layer are other ecological factors considered. The lepidopterous fauna is richest on pine bogs. A list is given of the most typical butterfly and moth species found on peatlands and an attempt has been made to assign the species to different peatland types, r = on pine bogs, n = on open bogs, l = on fens, k = on spruce swamps, + = on other biotopes, too, N = mostly or exclusively in Northern Finland and S = only in Southern Finland. It is stressed that the draining of peatlands has a very serious effect on the insect fauna owing to their high sensitivity to change in the microclimatic conditions. "

• Mikkola, Sähköposti: ei.tietoa@nn.oo