Artikkelit kirjoittajalta Timo Penttilä
Harvennusten ajoittaminen ojitetuilla soilla — metsiköittäin vai kunnostusojituksen yhteydessä kerralla kuntoon?
English title: Timing of thinnings in drained peatland stands.
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Metsäkeskusten kunnostusojitushankkeiden metsikkökuvioista muodostettiin satunnaisesti yhdistäen kolme 35–50 hehtaarin suunnittelualuetta, joiden avulla tarkasteltiin ns. kerralla kuntoon -menettelyn mukaisten (toteutetaan kunnostusojituksen lisäksi kaikki tarpeelliset metsänhoitotoimet yhdellä kerralla koko suoalueelle) ja toisaalta metsänhoitosuosituksia kuvioittain mukailevien metsänkäsittelyjen tuotos- ja talousvaikutuksia. Pääasiassa karuhkoja rämeitä edustavien alueiden puustojen kehitykset simuloitiin kunnostusojituksen ajankohdasta päätehakkuuseen saakka. Erityishuomiota kiinnitettiin alueisiin sisältyvien vähäpuustoisten kuvioiden ensiharvennusten voimakkuuteen sekä harvennusten ajoittumiseen suhteessa kunnostusojitukseen. Harvennusten myöhentäminen sekä vähäpuustoisilla että muilla ns. normaalipuustoisilla kuvioilla paransi koko suunnittelualueen pitkän aikavälin taloustulosta jonkin verran, mutta vähäpuustoisten kuvioiden käsittelyajankohdan vaikutus oli selvästi suurempi. Harvennuksia myöhentämällä myös ensiharvennusten ainespuukertymä kasvoi. Jos vähäpuustoiset kuviot kuitenkin harvennettiin kunnostusojitusvaiheessa ja samaan aikaan normaalipuustoisten kuvioiden kanssa, paras tulos saavutettiin suhteellisen voimakkailla harvennuksilla. Vähäpuustoisten kuvioiden jättäminen kokonaan harventamatta johti heikoimpaan aluetason taloustulokseen. Metsänkasvatuksen pidemmän aikavälin kannattavuutta voitaisiin käytännössä parantaa rajaamalla kunnostusojitusalueen vähäpuustoiset kuviot omiksi käsittelylohkoikseen ja siirtämällä niiden harvennukset toteutettaviksi vasta alueen seuraavalla hakkuukierrolla.
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Kojola,
Soili Kojola, Metsäntutkimuslaitos, Etelä-Suomen alueyksikkö, PL 18, 01301 Vantaa, Puh./Tel. 029 532 2111, Fax: 029-532 2103, email: soili.kojola@metla.fi
Sähköposti:
ei.tietoa@nn.oo
- Penttilä, Sähköposti: ei.tietoa@nn.oo
Fosforin ainekierto rämemännikön puustossa ja pintakasvillisuudessa ojituksen jälkeen.
English title: Post-drainage dynamics of P uptake by trees and ground vegetation in Scots pine dominated peatlands.
Avainsanat:
mire;
secondary succession;
ecosystem functioning;
drainage for forestry;
nutrient cycling;
nutrient upatake;
Pinus sylvstris
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We investigated long-term dynamics of phosphorus (P) in ground vegetation, tree stand biomass and litterf all in two undrained and four drained oligotrophic pine fens in southern Finland. The study sites, which encompassed observation periods up to six decades after drainage, were chosen to form a chronosequcncc of sites initially similar floristically, showing different stages of the forest succession induced by drainage. The pattern of P allocation to above- and below-ground plant biomass followed the changes in growth form dominance from mosses, graminoids and shrubs to trees. Overall, net vascular plant uptake of P increased after drainage and remained on a higher level compared to that in the pristine fen. The amount of P in the drained ecosystem seems to remain high enough to support the uptake and continuing forest succession.
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Laiho,
Peatland Ecology Group, Department of Forest Ecology, University of Helsinki, P.O. Box 27, FI-00014 Helsinki University, Finland
Sähköposti:
ei.tietoa@nn.oo
- Penttilä, Sähköposti: ei.tietoa@nn.oo
- Vasander, Sähköposti: ei.tietoa@nn.oo
- Laine, Sähköposti: ei.tietoa@nn.oo
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.
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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
Lannoituksen vaikutus hieskoivikoiden kasvuun ja ravinnetilaan ojitetuilla turvemailla Pohjois-Suomessa.
English title: Effect of fertilization on growth and foliar nutrient status of pubescent birch stands on drained mires in northern Finland.
Avainsanat:
nitrogen;
phosphorus;
potassium;
peatland;
Foliar nutrients;
Betula pubescens;
growth responses
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The effects of fertilization and refertilization on the growth of pubescent birch (Betula pubescens) stands growing on drained peatlands in northern Finland were studied in eight field experiments. The treatments were: (i) control with no fertilization, (ii) fertilization with nitrogen (N), (iii) fertilization with phosphorus and potassium (PK), and (iv) fertilization with nitrogen, phosphorus, and potassium (NPK). The sites represented four different mesotrophic to eutrophic site types with stand median heights ranging from 7 m to 13 m. Tree growth was monitored at stand level during periods of five to eleven years following the setting up of the experiments and during periods of 4 to 7 years following the repetition of the treatments in 1985. At the end of the second period, sun-exposed leaves were sampled from two stands in August 1990 for the purpose of conducting foliar nutrient analyses. The first-time fertilization treatments did not affect tree growth on any of the site types. Following the repetition of the treatments, the stands responded positively to NPK or PK fertilization on all site types except on the shallow-peated herb-rich peatland forest. There was no response to mere N-fertilization on any of the site types. The growth responses observed were weaker than those reported for Scots pine in similar climatic conditions.
Key words: Betula pubescens, foliar nutrients, growth responses, nitrogen, peatland, phosphorus, potassium
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Penttilä,
The Finnish Forest Research Institute, Rovaniemi Research Station, P.O.Box 16, FIN-96301 Rovaniemi, Finland
Sähköposti:
ei.tietoa@nn.oo
- Moilanen, Sähköposti: ei.tietoa@nn.oo
Lannoituksen vaikutus kuusikoiden kasvuun ja ravinnetilaan ojitetuilla turvemailla Pohjois-Suomessa.
English title: Effects of fertilization on tree growt and nutrient status of Norway spruce stands on drained peatlands in northern Finland.
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Abstract: The stand-level responses to fertilization and refertilization were studied in seven factorial field experiments established in 1974-1976. The factors were nitrogen fertilization (N) and phosphorus-potassium fertilization (PK). The factorial treatments were applied at two levels: (i) control and (ii) fertilized with a dosage following the currently used Finnish forest fertilization guide-lines. The spruce-dominated stands were selected from areas drained according to normal forestry practises between 1932 and 1969. The sites covered fairly well the trophic variation that occurs on spruce-dominated peatlands in the mid-boreal zone in Finland. Tree growth was monitored during two periods of five to seven years. The second period followed the refertilization in 1985. At the end of the second period, one-year-old sun-exposed needles were sampled from the four southernmost stands for nutrient analyses. The effects of fertilization on tree growth were generally fairly weak and insignificant, especially during the first study period. After refertilization, the effect of N was positive in three stands on mesotrophic sites. The foliar nutrient analyses of unfertilized spruces showed low concentrations of N, P and Cu. PK-fertilization increased foliar P concentrations and, in some cases, also K concentrations. Since the PK-fertilizer included some borate, it also increased foliar B concentrations. N-fertilization did not affect foliar N, P or K concentrations but it decreased foliar concentrations of Ca, Zn, and B in some cases. Both the growth responses and the foliar nutrient analyses indicated that nitrogen was the most deficient macro-nutrient.
Key words: foliar nutrients, growth responses, mires, nitrogen, phosphorus, Picea abies, potassium
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Moilanen,
The Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie, FIN-91500 Muhos, Finland
Sähköposti:
ei.tietoa@nn.oo
- Penttilä, Sähköposti: ei.tietoa@nn.oo
- Issakainen, Sähköposti: ei.tietoa@nn.oo
Sekakoivikon reaktio ensiharvennukseen mustikkaturvekankaalla Lapissa.
English title: Thinning response of a young, birch-dominated mixed stand on Vaccinium myrtillus peatland forest type in Lapland.
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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
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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
Harvennushakkuun vaikutus pohjavedenpinnan syvyyteen ojitusalueilla Pohjois-Suomessa.
English title: Effect of thinning on groundwater table depth in drained peatlands in northern Finland.
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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
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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
Suometsätieteellinen tutkimus Ruotsissa.
English title: Peatland forestry research in Sweden.
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Former and present peatland forestry studies by the Department of Forest Soils of the Swedish University of Agricultural Sciences (Umeå) are presented, based on a tour to field experiments in north, mid and south Sweden. Up to the 1970s, major interest was paid to the nutrition of drained, originally treeless or sparsely treed fens and bogs. Several fertilization experiments since the first wood ash trials in Norra Hällmyren have indicated the necessity of P and K application to ensure afforestation and satisfactory growth of Scots pine on such sites. Silvicultural problems on drained peatlands, such as regeneration on highly productive peatlands, planting techniques, commercial thinnings, as well as gas exchange in peat and the distribution of nutrients in a peatland forest ecosystem are the focus of a large-scale project started in 1985. The preliminary results of the regeneration experiments, i.e. the effectiviness of spruce shelter wood (140-200 trees per ha) against frost damage during the growing season, are discussed. A brief description of the present classification and post-drainage site index system for peatlands is also given.
Keywords: Classification, drainage, nutrient status, regeneration
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Hökkä,
Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, SF-96301 Rovaniemi, Finland
Sähköposti:
ei.tietoa@nn.oo
- Penttilä, Sähköposti: ei.tietoa@nn.oo
Jatkolannoitus Lapin viljavilla rämeillä.
English title: Refertilization on meso-trophic pine swamps in northern Finland.
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The paper deals with the effects of refertilization on the growth response of pine growing on drained nitrogen-rich swamps in northern Finland. The results of five replicated factorial experiments are presented. Primary fertilization, mainly with PK, was carried out 10—13 years before refertilization with the following treatments: N, P, K and in three experiments also a micronutrient mixture (H). Growth responses were measured 4—6 years after refertilization.
Of the single factors, N had a positive effect in a shallow-peated experiment and the micronutrient mixture in a deep-peated one. The effect of P and K was not significant in any of the experiments. However, the treatment means showed a clear positive effect with NK or NKH, except in the northernmost experiment. The effect of PK strengthened towards the end of the study period. The results imply that primary fer-tilization, especially with P, still had an effect at the time of refertilization. Final conclusions concerning PK fertilization and also the effect of nitrogen should be based on a longer period of observation.
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Penttilä,
Sähköposti:
ei.tietoa@nn.oo
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