Suo - Mires and peat 51 (2000)

Summary: Organized by The International Peat Society (IPS), The International Asociation of Ecologists (INTECOL ), The International Mire Conservation Group (IMCG), and The Society of Wetland Scientists (SWS), The Millennium Wetland Event held in Québec City, Canada, on 6–12 August 2000 was the biggest ever organized congress devoted to mires and peat. Almost 1900 delegates (with accompanying persons almost 2100 participants) from 75 countries all over the world guaranteed that the programme and sessions were versatile and informative. The 12th IPS congress “Wise use of peatlands” will be organised in Tampere, Finland, between 6th and 11th August 2004 and that is why the Finnish candidate (Markku Mäkelä from Geological Survey of Finland) was elected as the first vice-president of IPS. Gerry Hood from Canada was elected as the president of IPS and Jack Rieley from Nottingham, UK, as the second vice-president for the next four years. In this review some Finnish specialists write about the themes they followed in Québec (Harri Vasander — general, Raimo Heikkilä and Leila Korpela — mire conservation and biodiversity of peatlands, Markku Mäkilä — peat geology, Sanna Saarnio — gas exchange studies, Juhani Päivänen and Sakari Sarkkola — ecology and management of forested peatlands, Arvo Leinonen and Pirkko Vesterinen — peat technology, Olli Reinikainen — horticulture, Juhani Päivänen — wise use of peatlands, Lasse Aro — restoration of peatlands and the post-congress excursion). The Millennium Wetland Event was considered to be a unique opportunity to visit, meet collegues and to update knowledge about mire and peat science. A great thank you for all the organisers of this magnificant occasion. Un grand merçi pour tous les organisateurs du congrès: "Évènement du millénaire sur les terres humides". C’était une occasion inoubliable et un excellent début pour le nouveau millénaire.

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

The occurrence of raw humus layer and its relationship to the structure of the vegetation and the environmental variables were studied on 501 sample plots located systematically in drained peatland forests. The drainage had been done in the 1930s – 60s. The correlation between the amount of raw humus and the two-dimensional GNMDS (global nonmetric multidimensional scaling) ordination space was 0.57. The thickness of the raw humus layer increased in the direction of the drainage succession gradient. The correlations between the thickness of the raw humus and the measured environmental variables were weak. The strongest correlation was with the stand volume (0.31) and the drainage age (0.21). Weakness of these correlations was most probably due to the regressive succession on many plots. On average, the raw humus layer was thickest , 6.5 cm, in Vaccinium vitis-idaea transformed type I (developed from genuine forested mires) and 5.4 cm in type II (developed from treeless or composite types). In Vaccinium myrtillus types the corresponding mean thickness was 5.2 cm (I) and 3.2 cm (II) and in dwarf-shrub types 3.3 cm (I) and 4.6 cm (II). The secondary succession is slower and the amount of the needle litter (of Pinus sylvestris) smaller in the dwarf-shrub type than in the V. vitis-idaea type. In the V. myrtillus type the origin of the litter is more dominated by deciduous trees, the decomposition faster and the coverage of Pleurozium schreberi clearly smaller than in the nutrient-poorer types. P. schreberi tolerates the litterfall well and together with especially conifer litter, and maybe with slow decaying fine roots, too, it forms a loose raw humus layer on old drained peatlands. Being a poor germination bed, the raw humus makes successful stand regeneration difficult.

• Saarinen, The Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
• Hotanen, Sähköposti: ei.tietoa@nn.oo

Both minerotrophic (fens and transitional mires) and ombrotrophic (raised bogs) mires occur in Latvia. Distribution of mires and diversity of mire vegetation are determined by geology of area, origin of mires and climatic differences between coastal and continental parts of Latvia. Fens started to develop in the early Holocene in the Preboreal 10 000 years BP. Later, during the Atlantic many fens transformed into transitional mires and gradually into raised bogs. Today Latvian mires are represented by all these types and they cover 4.9% of the country. Mires are protected in the North Vidzeme Biosphere Reserve, National Parks (Slitere, Kemeri and Gauja), Strict Nature Reserves (TeiEi, Krustkalni and Gripi), Nature parks and 140 nature reserves, as well as in protected landscape areas.

• Pakalne, Department of Botany and Ecology, university of Latvia, Kronvalda Boulevard 4, LV-1586, Riga, Latvia Sähköposti: ei.tietoa@nn.oo
• Kalnina, Sähköposti: ei.tietoa@nn.oo

The mycorrhizal infection of the roots of four-year-old Scots pine seedlings was stud ied by analysing root ergosterol, endogenous polyamines, nitrogen, phosphorus and potassium concentrations after two years in the field.The seedlings had been planted in a 25-year-old pine plantation on an originally treeless mire representing a wide peat nitrogen gradient.Common mycorrhizal types with Scots pine, such as Cenococcum Piloderma and Boletaceae types, and a number of unidentified types were found in the roots.The roots contained quite normal or a little lower levels of ergosterol than re ported elsewhere on tree roots in mineral soil forests.After two growing seasons in the field a positive correlation (r =0.584**)was found between the root ergosterol and peat nitrogen concentrations.The root ergosterol and spermidine concentrations correlated positively.This may be due to a more abundant physical presence of the fungal tissue which contains more spermidine than the other polyamines, or it may be due to a posi tive effect of the mycorrhizal fungi on the metabolic activity of the roots.

• Sarjala, Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
• Kaunisto, Sähköposti: ei.tietoa@nn.oo

Wetlands play a special role in diverting plant materials towards fossilisation. These habitats are sinks for the atmospheric carbon: mineralisation of organic materials is inhibited by specific effects of the local N and S cycles, anaerobiosis, low pH, etc. It is not surprising therefore that microbial activity was detected to be highest in the rhizosphere of wetland plants. Cattail (Typha angustifolia L.) withstands extremely low soil redox values. Cattail root samples were collected in a floating mat at the Soroksár Arm of the River Danube. The root-tip regions were used for bacteriological studies. Using the plate-count technique an average of 3.3*104 CFU/g actinomycete rhizoplane count was detected. All actinomycete colonies were isolated, purified, and strains subjected to differential diagnostic analysis (phenotypical and chemotaxonomical tests). The dominant rhizoplane actinomycetes were: Streptomyces anulatus, and Str. albidoflavus, Micromonospora chalcea and M. carbonacea, Micrococcus luteus, Brevibacterium sp. and Gordona sp. Streptomycetes were characteristic for autumn sample, whereas the other actinomycetes dominated the rhizoplane microbiota early in the vegetation period. The ecological tolerance abilities of the members of dominant groups indicate that these bacteria might be active in the rhizosphere and can be present there in their vegetative forms.

• Rifaat, Department of Microbiology, Eötvös Loránd University, Múzeum krt. 4/a., 1088 Budapest, Hungary Sähköposti: ei.tietoa@nn.oo
• Márialigeti, Sähköposti: ei.tietoa@nn.oo
• Kovács, Sähköposti: ei.tietoa@nn.oo

An inventory of wetlands in Poland was completed in 1994 and it opened the possibility of starting a planned supplementation of the reserve network on wetland.For this pur pose, it is necessary to carry out an evaluation of the existing objects.The studies include 52 existing and 72 planned nature reserves on wetland in the middle-west part of Poland (area of 33 600 km2 ).An original evaluation method uses seven criteria, which are evaluated in a three degree scale each.On this basis three classes (highest, medium, lowest value)were assigned.Only a small number of existing reserves are found in the extreme classes.In the highest class, there are only six nature reserves.In the lowest class there are small objects with little differentiated forest communities and high endangerment by degradation.A definite majority of the existing reserves are found on fens.Raised and transitional bogs are represented by a comparatively great number of small objects not exceeding 15 ha.The representativeness of the existing reserves in relation to the plant communities encountered on the wetland of this region is not the best one.

• Ilnicki, Agricultural University Pozna , Department of Environmental Protection and Management, ul. D browskiego 159, 60-594 Poznan, Poland Sähköposti: ei.tietoa@nn.oo

The gaseous plant hormone and air pollutant ethylene (C2H4) has a strong effect on plant physiological processes, such as ripening and senescence, and its removal is often required from contaminated air.This study tested the efficiency of indigenous microor ganisms in horticultural peat-soil to purify C2H4 contaminated air under biofilter condi tions.Peat-soil, acclimated to C2H4 removal, was placed in a biofilter (687 cm3) and subjected to an air flow (73 mL min–1 ) with ~117 ppm C2H4 (ppm, parts per million; equivalent to µL L–1 ).C2H4 was removed to a lowest level of 0.034 ppm after operation of the biofilter for 12 days at 26°C. This corresponded to a C2H4 removal efficiency of >99.9%and a specific C2H4 removal rate of 6.4 µg C2H4 g–1 dry wt soil h–1 (wt, weight). However, this efficient C2H4 removal was only transient (4 days), and during day 16 to 21, the C2H4 removal efficiency decreased to 51%. In contrast to this result, it was previously found that, under comparable biofilter conditions, cultivated ethylene-oxidizing bacteria were able to survive and efficiently remove C2H4 for at least 75 days. Thus, prolonged and efficient purification of highly C2H4 contaminated air by horticultural peat-soil under biofilter conditions apparently depended on bacterial inoculation.

• Elsgaard, Danish Institute of Agricultural Sciences, Department of Crop Physiology and Soil Science, Research Centre Foulum, P.O. Box 50, DK-8830 Tjele, Denmark Sähköposti: ei.tietoa@nn.oo

Soils store more carbon (C) than does vegetation and in Northern Ireland peat has been estimated to account for about 42% of the soil C store. This estimate, however, was based on incomplete field evidence, including uncertainty on peat depths and peat bulk density. This paper aims to show how the estimate might be improved, taking into account bulk density and carbon density measurement. Trial 3-D models are presented to estimate total C content of individual bogs. Results suggest that C stores in northern Irish lowland raised bogs are lower than previously estimated primarily because of low bulk densities which showed no consistent increase with peat depth. Bulk density varied within and between bog profiles on the same bog and between bogs leading to different estimates of C stores. The research indicates a need for more precise modelling of bogs based on stratigraphy and dating of layers and a need for standardised measurement of peat bulk density and carbon storage. The findings, particularly if they apply to the extensive blanket bog, affect local and national totals of soil C stores and have implications for national policies on increasing/preserving C stores.

• Tomlinson, School of Geography, The Queen’s University of Belfast, BT7 1NN, Northern Ireland Sähköposti: ei.tietoa@nn.oo
• Davidson, Sähköposti: ei.tietoa@nn.oo

A mechanistic simulation model of organic matter accumulation for a developing fen/ raised bog complex in Ireland is presented.Parameter/variable values have been prima rily drawn from the published literature.The development of the theoretical considera tions of fen peat as a substratum to a raised bog is evaluated using the model.Terrestri alization is the pathway of hydroseral succession.The conceptual model treats peat growth as the accumulation of a series of parcels comprising both a labile and a non- labile component.The fen phase of the model uses a discrete description of organic matter accumulation while the raised bog phase uses a continuous description.Both phases use a constant decay rate.The model integrates changes in net primary produc tivity and aerobic decay to simulate four climatic periods.The model generates outputs for peat depth and mass with time and profiles of bulk density with depth.Results over a simulated period of 10 000 years demonstrate how changes in surface net primary productivity and aerobic decay can change the rate of peat accumulation in the develop ing fen/raised bog complex.Sensitivity analysis showed that the most important pa rameters influencing simulated depth and mass were the labile fraction in organic mat ter (raised bog)followed by net primary productivity (raised bog).The potential sig nificance of underlying fen peat as a proportion of the total depth and mass of a devel oping fen/raised bog complex was evaluated and shown to be substantially diminished after 5 000 years.It was established that the model predictions corresponded well with data for Irish Midland bogs and given suitable adjustment of values, could potentially simulate Fennoscandian conditions as well.

• Gilmer, Department of Agricultural & Food Engineering (Peat Technology Centre), University College Dublin, Earlsfort Terrace, Dublin 2, Ireland Sähköposti: ei.tietoa@nn.oo
• Holden, Sähköposti: ei.tietoa@nn.oo
• Ward, Sähköposti: ei.tietoa@nn.oo
• Brereton, Sähköposti: ei.tietoa@nn.oo
• Farrell, Sähköposti: ei.tietoa@nn.oo

The liquid-soil contact angle indicates the wettability of a solid. This study was con ducted to determine the apparent water-solid contact angle in peat-moorsh soils located in the Biebrza River Valley using two indirect methods.One of them was the height of the capillary rise at the equilibrium, and the other was a dynamic capillary rise ap proach.The measured values of the contact angle ranged from 64.2 to 83.1 degrees using the equilibrium height of capillary rise approach, whereas for the dynamic capil lary rise method varied from 86.3 to 89.8 degrees.Comparison of the experimental results showed that the values of contact angles obtained using the dynamic capillary rise approach were about 12% higher than the values obtained from the capillary rise equation.The determined value of the apparent contact angle was affected by the gravi metric moisture content and bulk density.The contact angle values measured in peat- moorsh soils confirm that these soils exhibit some degree of hydrophobicity (water repellency)at all water contents and packed densities.

• Waniek, Department of Environmental Development and Land Improvement, Warsaw Agricultural University, ul. Nowoursynowska 166, 02-787 Warsaw, Poland Sähköposti: ei.tietoa@nn.oo
• Szatylowicz, Sähköposti: ei.tietoa@nn.oo
• Brandyk, Sähköposti: ei.tietoa@nn.oo

The paper presents the results of laboratory-and field-measured soil moisture retention characteristics for different layers in peat-moorsh soil developed from a fen.Field de termination was based on the measurements of the moisture content and pressure head values performed on undisturbed soil columns during a drying process.Laboratory measurements were performed with sand table and pressure chambers.In order to ob tain moisture retention characteristics related to actual volumetric moisture content, the shrinkage characteristics were measured for different soil layers.The comparison of the laboratory and field measured moisture retention characteristics showed that the results of field measurements were very close to those of laboratory measurements, expressed in terms of fictitious volumetric moisture content.This expression of water content based on initial soil volume provides a better estimation of differential water capacity.

• Oleszczuk, Department of Environmental Development and Land Improvement, Warsaw Agricultural University, ul. Nowoursynowska 166, 02-787 Warsaw, Poland Sähköposti: ei.tietoa@nn.oo
• Szatylowicz, Sähköposti: ei.tietoa@nn.oo
• Brandyk, Sähköposti: ei.tietoa@nn.oo
• Gnatowski, Sähköposti: ei.tietoa@nn.oo

The effect of tree stand thinning and ditch network maintenance on the water table level was studied in an uneven-aged Scots pine (Pinus sylvestris L.) stand growing on a drained dwarf shrub pine bog in southern Finland. The water table level was monitored once a week during the growing seasons (May–September) of 1991–1999. This time span is divided into the following treatment periods: calibration (1991–1992), thinning (1993–1994), ditch cleaning (1995), and proper ditch network maintenance (1996–1999). The growing season of 1995 was not included in the calculations because the ditch cleaning treatment failed. The layout included three thinning intensities (9.5, 15.0, and 28.1% removal of the initial stand volume) and an unthinned control. For the ditch maintenance treatment there was an additional control sample plot. The effect of the treatments on the water table level was evaluated both by a graphical approach and linear regression analysis. Only a slight, ecologically insignificant rise in the water table level was caused by the thinning cuttings. Ditch maintenance seemed to eliminate this change. It was concluded that in the planning stage, a careful evaluation of the real need of maintaining the ditch network (ditch cleaning or complementary ditching) should be done in connection with the first commercial thinning in order to avoid unnecessary costs.

• Päivänen, Department of Forest Ecology, Box 24, FIN-00014 Helsinki University, Finland Sähköposti: ei.tietoa@nn.oo
• Sarkkola, Sähköposti: ei.tietoa@nn.oo

Peat hydraulic conductivity, shear strength, plant composition and runoff at seven peat harvesting sites in Central Finland were measured. A large variation in hydraulic conductivity (10–8–10–6 m s–1 ), peat shear strength (302–413 kPa), and peak runoff (97–898 l s–1 km–2 ) was observed between different harvesting sites. The hydraulic conductivity showed a clear correlation with peat shear strength (r = –0.89), which has not been previously observed. The correlation between hydraulic conductivity and degree of humification was weak (r = 0.60). Soil lowering decreased the hydraulic conductivity and the peat shear strength. These reductions, with reduced drainage depths, increased peak flow and changed runoff generation patterns by increasing the possibility of Horton and saturation excess overland flow.

• Kløve, Jordforsk, Norwegian Centre for Soil and Environmental Research, 1432 Ås, Norway Sähköposti: ei.tietoa@nn.oo

A 800 ha area of drained peatlands in the Hautes-Fagnes (Belgium) was surveyed by means of a ground-penetrating radar and a global positioning system.The survey pro vided very accurate information about the subsurface relief and the thickness and extent of the peat deposit, as well as stratigraphical information and suggestions of possible links between subsurface, hydrology and present vegetation.

• Wastiaux, Université de Liège, Station scientifique des Hautes-Fagnes, rue de Botrange, 137, B-4950 Robertville, Belgium Sähköposti: ei.tietoa@nn.oo
• Halleux, Sähköposti: ei.tietoa@nn.oo
• Scumacker, Sähköposti: ei.tietoa@nn.oo
• Streel, Sähköposti: ei.tietoa@nn.oo
• Jacqmotte, Sähköposti: ei.tietoa@nn.oo

The aim of this work was to determine physical properties of organic soils developed in different sites of the mountain area of Stolowe Mountains National Park, Poland. The profiles with different botanical composition of peat were analysed and classified by types and species of peat. Peat, muck and peat-mud were identified (9 profiles) at chosen locations. Investigation showed that top plateau organic soils were developed on a sandy-loam or sand weathered sandstone base. Organic soils in valleys and slopes were developed on a loamy-silt or clay basement. Peat horizons developed according to different types of sites (mesotrophic and eutrophic, sometimes oligotrophic). Generally, these soils are ombrotrophic, i.e. fed by atmospheric water only. These soils were classified as Fibric Histosols and Terric Histosols. Organic soils within the main regions of the park were over-desiccated, with advancing muck-forming processes being noted.

• Bogacz, Institute of Soil Science and Agricultural Environment Protection, Agricultural University of Wroc aw 50-357 Wroc aw, ul. Grunwaldzka 53, Poland Sähköposti: ei.tietoa@nn.oo

Three Greek soil profiles originating mostly from lacustrine deposits in the district of Filippoi (Northern Greece), were studied. These soils have been formed both from organic and inorganic materials that were deposited by precipitation and developed through the action of aquatic organisms. According to Soil Taxonomy (1992), they are classified as Histosols and belong to the suborder of Saprists. The pH of the soil horizons ranged among soil horizons from 6.2 to 7.8. The total soil nitrogen content ranged between 7.5 and 17.0 g kg–1 and the soil organic matter was between 108.7 and 206.4 g kg–1 . Calcium carbonate was detected into ten horizons and ranged between 1.4 and 27.8%, whilst it was not found in five of the examined soil layers. This is suggested to reflect the presence or absence of aquatic organisms, the shells of which contain CaCO3 and enrich soil by means of weathering. Heavy metals extracted by 4 M HNO3 were in the following order Fe>Mn>Zn>Pb>Ni>Cu>Cd, and their average concentrations were 7190, 294, 72.3, 58.2, 33.3, 17.3 and 5.1 µg g–1 , respectively. The distribution of trace elements greatly differs amongst the examined samples and the range of the pseudototal form of Fe was 1873–18550 µg g–1 , of Mn 54.7–585, of Cu 4.5–40, of Zn 22.0–185, of Pb 20.5–143, of Ni 15–64.7 and Cd 3.3–6.9 µg g–1 . The sequentially extracted by Na2 -EDTA, HNO3 and NaOH were found to be the prevailing metal forms. Iron deficiency symptoms have been observed in certain crops, and manganese deficiency was also detected in some maize crops cultivated in slightly alkaline soils. Furthermore, the plant available boron concentration was determined, as deficiency symptoms were observed in some districts cultivated with sugar beets. The distribution was generally not influenced by soil properties, although a weak relationship between organic carbon and boron was found. Measures such as rational water management, tillage practices, and fertilization could be applied towards minimization of soil degradation, micronutrient disorders and optimization of crop productivity.

• Karyotis, National Agricultural Research Foundation, Institute for Soil Mapping and Classification, 1 Theophrastou Str., 41335 Larissa, Greece Sähköposti: ei.tietoa@nn.oo
• Haroulis, Sähköposti: ei.tietoa@nn.oo
• Vavoulidou, Sähköposti: ei.tietoa@nn.oo
• Papadopoulos, Sähköposti: ei.tietoa@nn.oo

A natural property of mires is their ability to accumulate carbon and nutrients in the form of peat.Drainage and agricultural land use have changed the nutrient balance from accumulation to mobilisation.In this study, the effect of land use and hydrology on nitrogen dynamics is quantified using a GIS-based dynamic modelling approach.In the simulation, the nitrogen budget is controlled by drainage depth, land use type and fertilizer application.Denitrification is, next to harvest, the quantitatively most impor tant output pathway from peat soils with a predominant vertical water flow.Only for the wet Caricion elatae type was a net nitrogen accumulation simulated.The spatial visualisation of the nitrogen balance shows a high variability based on the heterogene ity of the peatland.Rewetting and extensivication can reduce the deficit in the nitrogen balance and lead to a slight increase of the accumulating area.These simulation results can be used in environmental planning to define a more sustainable land use in the future.

• Trepel, Royal Danish School of Pharmacy, Section of Environmental Chemistry, Universitetsparken 2, DK-2100 Copenhagen, Denmark Sähköposti: ei.tietoa@nn.oo
• Davidsson, Sähköposti: ei.tietoa@nn.oo
• Jørgensen, Sähköposti: ei.tietoa@nn.oo

The state of the environment is currently evaluated by indicators of air and water quality. Sustainable land use requires an assessement of soil quality. Soil quality indicators should relate soil processes to management practices. The supply of N and P contributes to crop productivity, but can degrade air and water quality. In this paper, we will present organic soil N and P attributes that can make up soil functions. Nitrate was the only detected mineral N form in organic soil materials with pH (0.01M CaCl2 ) exceeding 4.4. Lowest C/N ratio of cultivated sapric soil materials was 15, showing high nitrate-supplying capability. Total P concentration was between 760 and 1960 mg P kg–1 both in organic and inorganic forms when pH (0.01M CaCl2 ) increased above 4.7, the recommended minimum pH value for cultivated organic soils. Lowest C/P ratio as organic forms was 340 for sapric materials containing less than 22% ash, indicating organic P sequestration capability (C/P > 300). However, the low N/P ratio of 23 (i.e. 340/15) also indicated capability for organic P availability to plants. Since N and P are related to organic matter transformations, the C/N/P/S multiratios of selected organic matter fractions, analyzed as compositional data (computation procedure presented), need further consideration as integrated N and P attributes in combination with pH and climatic indexes, in order to adapt N and P diagnosis and recommendation models to specific organic soil agroecological zones.

• Parent, Centre de Recherche en Géomatique, Laval University, Ste-Foy (Quebec), Canada G1K 7P4 Sähköposti: ei.tietoa@nn.oo
• Viau, Sähköposti: ei.tietoa@nn.oo
• Anctil, Sähköposti: ei.tietoa@nn.oo

Cultivation experiments on D. rotundifolia and D. anglica were carried out in peat beds in Mikkeli, South Finland (61°44’ N, 27°18’ E) in 1992-1997. Plants were propagated by direct sowing and transplanting of small seedlings in peat beds (size 3 m2, depth 0.7 m) filled with non-fertilized peat (pH 4.0). Seed germination, growth, flowering cycle as well as fresh herb and seed yields were measured. To increase the growth, plants were regularly fed milk powder. The 7-methyljuglone, quercetin and kaempferol contents of the flowers, leaves and stems were determined from sown and transplanted, fed and non-fed Drosera plants. Both Drosera species were successfully cultivated in peat beds. Direct sowing in autumn followed by natural winter stratification seemed to be the best propagation method. Flowering started after the second and third growing years. Feeding the plants milk powder increased growth by 27-113%. The fresh yield during the third, fourth and fifth years ranged between 0.05 and 0.9 kg m-2, being highest in the first and second harvest years. Plant density decides the yield of small-sized species. The average yield was about 50 times higher in peat beds than in the nature. Feeding milk powder did not affect the secondary metabolite contents. The 7-methyljuglone content was 13-81% higher in the fed Drosera rotundifolia plants than in the non-fed ones. The quercetin and kaempferol contents were lower in the fed plant, 10-30% and 1-10% lower in D. rotundifolia and 30-60% and 1-15% lower in D. anglica, respectively. According to the results, it seems to be possible to grow Drosera rotundifolia and D. anglica under controlled conditions outside the natural ecosystem. The results also suggest that higher yields can be expected by cultivation of these species.

• Galambosi, Ecological Production, Resource Management, Agricultural Research Centre of Finland, FIN-50600 Mikkeli, Finland Sähköposti: ei.tietoa@nn.oo
• Galambosi, Sähköposti: ei.tietoa@nn.oo
• Repcák, Sähköposti: ei.tietoa@nn.oo

Yield potential and the effect of strict collection on the regeneration of natural populations of Drosera rotundifolia were studied in Finland during 1993-1999. Flowering plants were collected in July from 37 sample plots 1 m2 in size. Plant number, height of flowering plants, fresh weight as well as 7-methyljuglone, quercetin and kaempferol contents were determined. The average plant density was 45-56 plants m-2, and the average fresh weight was 6.3-6.7 g m-2 in the first and second years of collection. Regular and strict collection decreased significantly the population density. The average plant number in the third and seventh years ranged between 21 and 29 plants m-2. The collected fresh weight decreased respectively from 6.7g m-2 to 2.7g m-2. At the end of the vegetation periods the number of new seedlings averaged 188 m-2 on the observation plots, implying that the population may easily regenerate from the seed bank stock of the peat. According to the results of these experiments, the 4H organization elaborated a new, environmentally friendly collection programme for young collectors. The collectors were obliged to leave 5-10 flowering plants to spread seed and to assure natural regeneration of sundew populations.

• Galambosi, Ecological Production, Resource Management, Agricultural Research Centre of Finland, FIN-50600 Mikkeli, Finland Sähköposti: ei.tietoa@nn.oo
• Takkunen, Sähköposti: ei.tietoa@nn.oo
• Repcák, Sähköposti: ei.tietoa@nn.oo

The thermal conductivity of low-decomposed Sphagnum peat, used as a growth medium for container seedling production in tree nurseries, and of a sandy mineral soil was studied using the single thermal probe method in the laboratory. The thermal conductivity of the peat was low and decreased from 0.5 to 0.05 W m-1K-1 when the water content decreased from near saturation to air-dry. In comparison, the thermal conductivity of the sandy soil was much higher, decreasing steeply from 1.5 to 0.5 W m-1K-1 with decreasing water content. Results are in accordance with those reported earlier for similar media. The results suggest markedly weaker and more delayed temperature fluctuations in pure peat media compared with media containing mineral soil, which is in agreement with observations made in tree nurseries.

• Heiskanen, Finnish Forest Research Institute, Juntintie 40. FIN-77600 Suonenjoki, Finland Sähköposti: ei.tietoa@nn.oo

Logistic regression models were developed to predict the condition of ditch networks in drained peatland sites in Finland. The data consisted of observations from two forest inventories in which the need for ditch network maintenance had been assessed in the field by classifying the condition of the ditches in the sample stands. In the analysis an indicator variable which referred to one of two condition categories (in need of repair – not in need of repair) was used as the response variable. According to the results, the probability of being in the poor condition category was higher in sites where the time elapsed since drainage was longer, the geographic location was more northern, peat thickness was greater, and plot inclination was smaller. At a probability level of 0.5, the models predicted the category correctly in 69% of the sites in the modeling data, on average. The models were applied to a growth simulator to study the effect of poor drainage conditions on stand-level growth forecasts.

• Hökkä, Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Rovaniemi, Finland Sähköposti: ei.tietoa@nn.oo
• Alenius, Sähköposti: ei.tietoa@nn.oo
• Salminen, Sähköposti: ei.tietoa@nn.oo

Summary: The habitats of particular significance referred to in the forest act 10 § include following mire site types: herb-rich spruce swamp woods, eutrophic fens (south of the Province of Lapland) and scrubland and wasteland sparsely treed mires. Lounais-Suomi forestry centre has invented those habitats of particular significance 1997-99. This matter was also studied by the 9th National Forestry Inventory (1998). The detailed directions concerning mire site types of habitats of the forest act are performed by quide Meriluoto & Soininen (1998). Also Lounais-Suomi forestry centre has observed mainly this quide. There is however a problem with some site types for ex. herb-rich sedge hardwood-spruce fens and herb-rich sedge birch-pine fens of scrubland and wasteland, which are not classified for habitats of the forest act. Because they are rare and there is no clear legal obstacle, those mire site types are also classified habitats of the forest act by Lounais-Suomi forestry centre. Only 25 % of the mires are in Southwest Finland are in virgin state and about 15 % of these mires are located in nature preserve areas. The inventory result of the forestry centre states, that there are 863 hectacres of mire habitats of particular significance referred to in the forest act in Southwest Finland mires, which is only 1.4 % of virgin mires outside nature preserve areas. NFI 9 found three times more habitats of the forest act than the inventory of the forestry centre, because NFI 9 cannot take into account territorial frequency of habitats and demand of small size of objective. However the distribution of mire site types is similar in both inventories. The inventory result of Lounais-Suomi forestry centre proves that there is a relatively small number of herb-rich level mire site types. Especially herb-rich sedge hardwood-spruce fen (RhSK) is very rare. It is important to classify all herb-rich level mires (taking into account the restrictions of the forest act) for habitats of the forest act in the future and also in natural state which is not wholly perfect. Nutrient-poor bogs are mainly consisted of virgin mire site types. They are often large mire complexes and in that sense not suitable habitats of the forest act. In this inventory nutrient-poor bogs represent one fourth of the total number. In the future it is sensible to choose only the most representative nutrient-poor bogs for habitats of the forest act.

• Silver, Sähköposti: ei.tietoa@nn.oo
• Kajava, Sähköposti: ei.tietoa@nn.oo