Artikkelit jotka sisältää sanan 'ditching'
Metsäojituksen vaikutuksesta ilmastoon.
English title: Climatic impacts of forestry on drained boreal peatlands.
Original keywords:
turvemaa;
ojitus;
hiilidioksidi;
metaani;
kasvihuonekaasut;
typpioksiduuli;
suometsätalous
English keywords:
peat;
peatland forestry;
ditching;
Carbon dioxide;
methane;
nitrous oxide;
greenhouse gases
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Metsäojitus vähentää merkittävästi soiden metaanipäästöjä. Rehevien ruoho- ja mustikkaturvekankaiden maaperä on kuitenkin merkittävä hiilidioksidin lähde ilmakehään turpeen vähenemisen takia. Karujen puolukka- ja varputurvekankaiden turve ei näyttäisi nykyisin merkittävästi vähenevän. Puustobiomassan merkittävän suurenemisen ansiosta Suomen metsäojitetut suot ovat tällä hetkellä kasvihuonekaasujen nettonielu.
Ilmastonmuutoksen hillitsemisen kannalta metsänkasvatuksen jatkaminen lienee paras maankäyttömuoto metsäojitetuille soille lähivuosikymmenten aikana. Vaikka laajamittaisella ennallistamisella voitaisiin estää rehevien soiden turpeen väheneminen, samalla kuitenkin puuston kasvu vähenisi ja metaanipäästö kasvaisi. Ennallistamisen jälkeen kestänee vähintään kymmeniä tai satoja vuosia, ennen kuin saavutetaan ilmaston kannalta metsänkasvatuksen jatkamista parempi tilanne. Pitkällä aikavälillä rehevien soiden ennallistaminen on kuitenkin ilmaston kannalta parempi vaihtoehto, koska jo muutaman kymmenen senttimetrin paksuisen turvekerroksen häviäminen vapauttaa enemmän hiiltä ilmakehään kuin kookaskaan puusto pystyy sitomaan itseensä.
Metsäojitettujen soiden kasvihuonekaasutaseista on viime vuosina kertynyt melko kattavasti tietoa. Jotta metsätalouden jatkamisen tai mahdollisen puuston kasvamaan jättämisen tai suon ennallistamisen ilmastovaikutuksen suuruutta voidaan täsmällisesti arvioida, tarvitaan vertailulaskelmia eri vaihtoehtojen kasvihuonekaasupäästöistä. Suuren kokonaispinta-alan takia metsäojitettujen soiden tulevalla käytöllä voi olla suuri vaikutus Suomen kasvihuonekaasupäästöihin.
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Ojanen,
Luonnonvarakeskus (LUKE)
Sähköposti:
paavo.ojanen@helsinki.fi
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.
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Lauhanen,
The Finnish Forest Research Institute, Kaironiementie 54, FIN-39700 Parkano, Finland
Sähköposti:
ei.tietoa@nn.oo
- Ahti, Sähköposti: ei.tietoa@nn.oo
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.
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Päivänen,
Department of Forest Ecology, Box 24, FIN-00014 Helsinki University, Finland
Sähköposti:
ei.tietoa@nn.oo
- Sarkkola, Sähköposti: ei.tietoa@nn.oo
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.
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Lauhanen,
The Finnish Forest Research Institute, Kaironiementie 54, FIN-39700, Parkano, Finland
Sähköposti:
ei.tietoa@nn.oo
- Kaunisto, Sähköposti: ei.tietoa@nn.oo
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
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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
Kaivukaluston tuottavuus, työnjalki ja kustannukset kunnostusojituksessa.
English title: The productivity, work quality and the costs of employing backhoes and excavators in ditch network maintenance.
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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
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Lauhanen,
The Finnish Forest Research Institute, Kannus Research Station, FIN-69100 Kannus, Finland
Sähköposti:
ei.tietoa@nn.oo
Kaivukoneiden ajankäyttö ja tuottavuus metsäojituksessa.
English title: Time consumption and productivity of excavators in forest drainage.
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The distribution of effective time, output and work quality of three medium-sized excavators were observed in a time study. The distribution of operation time and productivity were included in a follow-up study. Digging time varied between 81-91%. Average availability was 85% and the productivity/operation time 157 m/h during ditch digging. The corresponding values during ditch cleaning were 89% and 221 m/h.
Keywords: Digger, ditching, effective time, excavator, operation time
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Salo,
Pappilantie 2, SF-60550 Nurmo, Finland
Sähköposti:
ei.tietoa@nn.oo
Puuntuotannon ja puunhankinnan kehittämismahdollisuudet Etelä-Lapin ojitetuilla soilla.
English title: The development opportunities of silviculture and wood procurement on drained peatland forests in southern Lapland, Finland.
English keywords:
Drainage;
ditching;
site type;
harvesting;
thinning;
tree species;
carrying capacity;
forest management
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