Suo - Mires and peat

Sylvain Jutras, André Plamondon. Vedenpinnan nousu avohakkuun jälkeen ojitetulla puustoisella suolla.

English title: Water table rise after harvesting in treed fen previously drained for forestry.

Avainsanat: forest drainage; water table level; forested peatland; black spruce

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Water table measurements were obtained in a treed fen that was drained in 1987 and harvested for timber in 1997. The water table level was quantified at five different distances from the ditch for three ditch spacing. Water table levels were compared between pre-drainage, post-drainage and post-removal of the canopy. The phenomenon of watering-up after clear-cutting did not occur where a drawdown of at least 10 cm was caused by the drainage. This lowering was observed across the 20 m ditch spacing and within the first 6 m from the ditch, in the 40 and the 60 m spacing. The water table fluctuations were also reduced after harvesting.

Jutras, Forest Biology Research Centre, Université Laval, Sainte-Foy, QC G1K7P4 Canada Sähköposti: ei.tietoa@nn.oo
Plamondon, Sähköposti: ei.tietoa@nn.oo

Risto Lauhanen, Erkki Ahti. Kunnostusojituksen vaikutus rämemänniköiden kehitykseen.

English title: Effects of maintaining ditch networks on the development of Scots pine stands.

Avainsanat: forest drainage; peatland; ditch cleaning; complementary ditching; tree stand; Pinus sylvestris L.; volume growth

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This study aimed at finding out the effects of maintaining ditch systems by ditch cleaning and complementary ditching on volume growth of drained Scots pine (Pinus sylvestris L.) stands. Volume growth during the first ten post-treatment years was increased by 0.16 m3 ha-1 a-1 after ditch cleaning, 0.36 m3 ha-1 a-1 after complementary ditching, and 0.48 m3 ha-1 a-1 after the combined treatment. The average growth reactions during the second five-year period were considerably higher than during the first one. No drastic reductions in stand growth, however, occurred in the untreated plots during the post-treatment period of ten years.

Lauhanen, The Finnish Forest Research Institute, Kaironiementie 54, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
Ahti, Sähköposti: ei.tietoa@nn.oo

Juhani Päivänen, Sakari Sarkkola. The effect of thinning and ditch network maintenance on the water table level in a Scots pine stand on peat soil.

Avainsanat: forest drainage; peatland; hydrology; ditch cleaning; complementary ditching; tree harvesting

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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

Hannu Hökkä, Virpi Alenius, Hannu Salminen. Kunnostusojitustarpeen ennustaminen ojitusalueilla.

English title: Predicting the need for ditch network maintenance in drained peatland sites in Finland.

Avainsanat: forest drainage; ditch network maintenance; logistic regression; site

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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

Risto Lauhanen, Seppo Kaunisto. Kunnostusojituksen vaikutus rämeiden ravinnetilaan.

English title: Effect of drainage maintenance on the nutrient status on drained Scots pine mires.

Avainsanat: forest drainage; peat; Scots pine; ditch cleaning; complementary ditching; nutrients; needles

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The effects of drainage maintenance on the nutrient contents in peat and Scots pine needles on drained pine mires were studied. The material consisted of twelve Finnish field experiments. Drainage maintenance (increasing ditching intensity; no treatment at all, mere ditch cleaning, mere complementary ditching, and both of them together) was carried out in 1982-1985. The needles were sampled in 1994-1995 and peat in 1996. There were great differences in the site types and consequently also in the peat and needle nutrient concentrations between the experiments. The needle Mn concentrations demonstrated a fairly good drainage status in all the treatments. Drainage maintenance had only minor effects on the nutrient status of peat and needles. Ditch cleaning decreased magnesium, manganese and zink amounts in the surface peat. Increasing the intensity of drainage maintenance increased the 100-needle dry mass, but decreased the needle boron concentrations. Peat and needle nitrogen concentrations increased slightly (not significantly) along with the increased intensity in drainage maintenance. The peat nutrients classified correctly 83.7% of the fertility classes for drained peatlands.

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

Risto Lauhanen, Marja-Leena Piiroinen, Timo Penttilä, Eero Kolehmainen. Kunnostusojitustarpeen arviointi Pohjois-Suomessa.

English title: Evaluation of the need for ditch network maintenance in northern Finland.

Avainsanat: forest drainage; ditch cleaning; complementary drainage; tree stand; stand growth; decision making

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Factors affecting the need for ditch network maintenance in northern Finland were studied. In addition, the effect of ditch network maintenance on stand growth was estimated. A dataset containing ditch, tree stand, site type and climate variables was built up on the basis of the permanent sample plots (SINKA) on peatlands. Regression analysis as well as discriminant analysis were used to identify factors and criteria that could be used to identify sites that would respond to ditch network maintenance. Instead of the ditch condition class, ditch age and depth proved to be the variables reflecting the need for ditch network maintenance. The volume of the tree stand was influenced the most by the temperature sum and age of ditching. Stand volume growth was influenced the most by the volume of the tree stand. The site type index or the volume of the tree stand did not give useful information for the planning of ditch network maintenance. When ditch age was 10-40 years, complementary ditching increased annual stand growth of pine mires by 0.6-1.0 and 1.5-1.9 m3 ha-1 a-1 on spruce-birch swamps.

Lauhanen, The Finnish Forest Research Institute, Parkano Research Station, FIN-39700 Parkano, Finland Sähköposti: ei.tietoa@nn.oo
Piiroinen, Sähköposti: ei.tietoa@nn.oo
Penttilä, Sähköposti: ei.tietoa@nn.oo
Kolehmainen, Sähköposti: ei.tietoa@nn.oo

Leena Hytönen, Jukka Aarnio. Kunnostusojituksen erilliskannattavuus muutamilla karuhkoilla rämeillä.

English title: Profitability of ditch-network maintenance on some oligotrophic pine mires.

Avainsanat: forest drainage; Scots pine; internal rate of return; net present value

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The paper presents the results of a study to assess the profitability of ditch-network maintenance on some oligotrophic pine mires. The alternative ditch-network maintenance methods compared were: ditch cleaning, complementary ditching, and ditch cleaning and complementrary ditching combined. Nine drained pine-dominated mires were chosen for investigation. Only the ditch-network maintenance costs were included in the calculations. Profitability was calculated for two cases: 1) the forest owner pays all the costs and 2) he obtains the maximum state grant. Without the state grant ditch-network maintenance provided a net present value of 870 FIM ha-1 with a 3 % rate of interest, of 220 FIM ha-1 with the 5 % rate of interest, and on internal rate of return of 5 %. With the state grant the results were: 1620 FIM ha-1, 970 FIM ha-1 and 10%, respectively. The conclusions were that in most cases ditch-network maintenance is profitable even without state grant. By using 3 % and 5 % interest rates, the complementary ditching and combination provided similar profitability, specially when the state grants were provided. Using the IRR criterion, the complementary ditching provided the best profit.

Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland Sähköposti: ei.tietoa@nn.oo
Aarnio, Sähköposti: ei.tietoa@nn.oo

Hannu Hökkä, Timo Penttilä. Sekakoivikon reaktio ensiharvennukseen mustikkaturvekankaalla Lapissa.

English title: Thinning response of a young, birch-dominated mixed stand on Vaccinium myrtillus peatland forest type in Lapland.

Avainsanat: forest drainage; growth; thinning; Betula pubescens

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The five-year response of a birch-dominated mixed stand (80% Betula pubescens, 14% Betula pendula) to thinning was studied in a thinning experiment in a mesotrophic, shallow-peated site in Ylitornio, northern Finland. Four thinning intensities (0%, 47%, 57% and 71 % removal of the initial stem number, i.e. 0%, 17%, 27% and 52% removal of the initial basal area), with three replications, were arranged in a randomized block design. At the time of thinning, the stand age was 30 a, and the dominant height was 11.5 m. Light (15%) and normal (27%) thinning decreased the rates of stand-level basal area growth by 12 and 15%, respectively. Thinning resulted in a significant increase in the growth of mean height and a subsequent increase in volume growth in the normally-thinned plots. Following heavy thinning, the volume and basal area growth rates were 35% and 32% less than those in the control treatment. The relative basal area increment, as well as the increase in mean diameter, was at its maximum in the heavily-thinned plots. Keywords: Betula pubescens, forest drainage, growth, thinning

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

Risto Lauhanen, Pekka Pietiläinen, Markku Saarinen, Eljas Heikkinen. Väri-infrakuvat kunnostusojituksen kohdevalinnan tukena.

English title: Usability of infra red imagery in the planning of ditch network maintenance.

Avainsanat: forest drainage; biodiversity; ditch cleaning; environmental protection; complementary ditching; IR imagery; decision making system

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The purpose of the study was to determine the usability of infra red imagery in evaluating the need for ditch network maintenance on nutrient-poor Scots pine mires. After interpreting a total of 75 tree stands in six peatland areas from the IR imagery, the stands were inventoried in the field. Site type, growing stock and ditch condition were determined. In addition, possible silvicultural treatments were suggested. Sphagnum fuscum, reddish-brown in the imagery indicated ditching areas unsuitable for ditch cleaning or complementary ditching. The estimated mean volumes of the tree stands were -37-+11% of the mean ground inventory values. The true proportions of tree species were in good agreement with the estimations based on the TR imagery. All in all, it was concluded that IR imagery is suitable in evaluating the need for ditch network maintenance on nutrient-poor mires. However, the validity of the method depended on the quality of the imagery and the skill of the interpreter. Keywords: forest drainage, ditch cleaning, complementary ditching, IR imagery, decision making system, environmental protection, biodiversity

Lauhanen, The Finnish Forest Research Institute, Kannus Research Station,FIN-69101 Kannus, Finland Sähköposti: ei.tietoa@nn.oo
Pietiläinen, Sähköposti: ei.tietoa@nn.oo
Saarinen, Sähköposti: ei.tietoa@nn.oo
Heikkinen, Sähköposti: ei.tietoa@nn.oo

Hannu Hökkä, Timo Penttilä. Harvennushakkuun vaikutus pohjavedenpinnan syvyyteen ojitusalueilla Pohjois-Suomessa.

English title: Effect of thinning on groundwater table depth in drained peatlands in northern Finland.

Avainsanat: forest drainage; Pinus sylvestris; groundwater table; thinning

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The effect of thinning on the groundwater table level was studied in four stands of Scots pine (Pinus sylvestris) on drained peatlands in northern Finland. Four thinning intensities (0-50% removal of the initial stocking), with three replications arranged using a randomized block design, were used in each experiment. If found to be in an unsatisfactory condition, the ditch networks were repaired at the time of thinning. Data from nine groundwater wells on each plot were used to determine the average depth of the groundwater table. The wells were monitored at two-week intervals during the latter parts of the growing seasons in 1991-1993. The mean groundwater table depth was used as the dependent variable in ANOVA with repeated measurements. In most cases, the groundwater table depth was lowest in the control plots, but significant differences between the treatments were found only in 1993 in two experiments. It was concluded that thinning caused no rise, or only a slight rise, in the groundwater table level. Keywords: Forest drainage, groundwater table, Pinus sylvestris, thinning

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

Risto Lauhanen. Kaivukaluston aiheuttamat puustovauriot kunnostusojituksessa.

English title: Tree damage caused by excavating machines in ditch network maintenance.

Avainsanat: forest drainage; excavator; ditch cleaning; work studies; backhoe; ditch digging; environmental protection

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An inventory of tree damage caused by five excavators, four backhoes and one small-size single-track backhoe was carried out in western Finland during the frost free season. The proportion of damaged trees was 1.1-2.4 % in tree stands ditched using backhoes and excavators, if the ditch lines had been opened in advance. The corresponding proportion caused by the single-track backhoe was 0.9%, if the ditch lines had not been opened in advance. The damage to tree stands was affected by the machine type, the work type and the width of the opened ditch line. Excavators caused more stem damage in the ditch cleaning than backhoes did (p<0.02). The mean distances of the damaged trees from the center line of the ditch were 226-264 cm on the work sites ditched using backhoes and excavators. The mean DBH of the damaged trees was 8-10 cm depending on work and machine type. The optimum width of the ditch line for the different machine types was assumed to be 400-500 cm when considering the growth losses of tree stand, the tree damage and the work productivity. Keywords: backhoe, ditch cleaning, ditch digging, environmental protection, excavator, forest drainage, work studies R. Lauhanen, The Finnish Forest Research Institute, Kannus Research Station, FIN-69101 Kannus, Finland

Lauhanen, The Finnish Forest Research Institute, Kannus Research Station, FIN-69101 Kannus, Finland Sähköposti: ei.tietoa@nn.oo

Risto Lauhanen. Kaivukaluston tuottavuus, työnjalki ja kustannukset kunnostusojituksessa.

English title: The productivity, work quality and the costs of employing backhoes and excavators in ditch network maintenance.

Avainsanat: forest drainage; additional ditching; ditch cleaning; excavating machines; work studies

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Four backhoes and four excavators were studied in different excavation difficulty classes (1-5) during the unfrozen period in the western part of Finland. The productivity (per effective hour) of the backhoes in ditch digging (additional ditching) was 54-172 m/h and 68-202 m/h in ditch cleaning. The productivity of the excavators was 114-289 m/h and 88-250 m/h, respectively. Productivity decreased as the difficulty class increased. It was affected by the width of the ditch line opening, the stoniness, and ditch depth. Productivity seemed to be affected by the machine operator, too. The work quality was acceptable. The operating costs were 268-388 FIM per hour for the machines costing 400 000-1000 000 FIM. Key words: additional ditching, ditch cleaning, excavating machines, forest drainage, work studies

Lauhanen, The Finnish Forest Research Institute, Kannus Research Station, FIN-69100 Kannus, Finland Sähköposti: ei.tietoa@nn.oo

Stanislav E Vompersky, Ivanov Anatolij. Soiden luokittelu metsätaloutta varten entisessä Neuvostoliitossa.

English title: Classification of mires in the forestry in the former USSR.

Avainsanat: forest drainage; Russia; Latvia; Lithuania; Siberia

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Peatlands and paludified forests have been regarded and classified as forests on peat soil in the former USSR. Treeless mires and sparsely forested mires with poor-quality tree stands have considered to be real mires. That is why in Russia, the term of forest type is traditionally used instead of mire type. The dominant tree species has the indicator role of the site type and this is also reflected in the name of the forest type. Besides the nationwide classification based on Sukachev's works, there are also some interesting regional (now national) classification systems especially in Latvia and Lithuania. Key words: forest drainage, Latvia, Lithuania, Russia, Siberia

Vompersky, Institute of Forest Research, Russian Academy of Sciences, Uspenskoye, Moscow Region, 143030 Russia Sähköposti: ei.tietoa@nn.oo
Anatolij, Sähköposti: ei.tietoa@nn.oo

Paula Isoaho, Risto Lauhanen, Markku Saarinen. Metsäojien jatkuvan kunnossapidon vaikutus ojitusalueiden tilaan Keski-Pohjanmaalla.

English title: Effects of continuous ditch network maintenance on the condition of forest drainage areas in Central Ostrobothnia district.

Avainsanat: forest drainage; Alternative excavating methods; ditch maintenance; stand volume

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The estimated annual need for ditch network maintenance in Finnish peatland forests is over 100 000 hectares, most of it consisting of ditch cleaning. However, there are not enough funds available for the needs of remedial ditching. In addition, environmental aspects in peatland forestry must be considered more than in the past. Thus, it is necessary to evaluate alternative work methods of ditch network maintenance. This paper presents the effects of continuous ditch network maintenance on the dimensions and the condition of ditches, as well as on the development of the tree stands on ditched sites. Key words: Alternative excavating methods, ditch maintenance, forest drainage, stand volume

Isoaho, The Finnish Forest Research Institute, Kannus Research Station, FIN-69100 Kannus, Finland Sähköposti: ei.tietoa@nn.oo
Lauhanen, Sähköposti: ei.tietoa@nn.oo
Saarinen, Sähköposti: ei.tietoa@nn.oo

Peitsa Mikola. Suot Suomen metsätaloudessa.

English title: Peatlands in Finnish forestry.

Avainsanat: forest drainage; peatlands

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Up to the present 5 Mha of peatland, i.e. 50% of the total peatland area of Finland, have been drained for forestry. The annual growth of peatland forests has increased from 6 Mm3 in the 1920s up 15 Mm3 in the 1980s, which is 22% of the total annual growth of the country's forests. To maintain the drainage systems, about 40 000 km of ditches should be cleaned annually. Silvicultural management of tree stands on peatlands is another urgent task in the near future. Keywords: Forest drainage, peatlands

Mikola, Department of Silviculture, University of Helsinki, Unionin-Icatu 40 B, SF-00170 Helsinki, Finland Sähköposti: ei.tietoa@nn.oo

Eero Paavilainen. Satakunnan suometsien kehitys vuosina 1977-1987.

English title: The development of peatland forests in Satakunta Forestry Board District between 1977 and 1987.

Avainsanat: forest drainage; inventory; peatland forests

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The development of peatland forests over a 10-year-period (1977-1987) in Satakunta Forestry Board District, Western Finland, is presented, based on the results of the 7th and 8th National Forest Inventories. Over this period the amount of peatlands classified as forest land (MAI over bark over a 100 years rotation ≥ 1 m3ha-1) and the total volume and increment of peatland forests considerably increased, mainly as a result of drainage. Keywords: Forest drainage, inventory, peatland forests

Paavilainen, Finnish Forest Research Institute, P.O. Box 18, SF-01301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo

Henry Schneider. Quebecin soista ja metsäojitustoiminnasta.

English title: Peatlands and forest drainage in Quebec, Canada.

Avainsanat: Quebec; forest drainage; site type classification

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The interest in peatland forestry in Quebec is increasing as the peatlands of the St-Lawrence valley are considered to have a good drainage response capacity A relatively important forest drainage project is being carried out on a practical scale. However, the lack of a practically oriented peatland classification system is an important drawback. This paper is an attempt to produce a preliminary classification system intended for practical peatland forestry. Keywords: Quebec, forest drainage, site type classification.

Schneider, University of Helsinki, Department of Peatland Forestry, Unioninkatu 40 B, SF-00170 Helsinki, Finland Sähköposti: ei.tietoa@nn.oo

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