Artikkelit jotka sisältää sanan 'ditch maintenance'

Samuli Joensuu, Erkki Ahti, Martti Vuollekoski. Kunnostusojituksen pitkän ajan vaikutus valumaveden ominaisuuksiin.
English title: Long-term effects of maintaining ditch networks on runoff water quality.
Avainsanat: peatland; ditch maintenance; runoff quality
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The effects of ditch network maintenance on runoff water quality was studied at 23 sites in different parts of Finland. The study included a calibration period of 1–3 years before maintaining the ditches and six years after. No observations were made during winter. After ditch maintenance, which involves either cleaning of old ditches and/or digging of complementary new ditches, the concentrations of suspended solids in runoff water increased immediately. At sites where the ditches cut into fine-textured subsoil, runoff continued to have increased suspended solids concentrations throughout the whole six-year period. However, if the bottom of the ditches consisted of coarse mineral subsoil or peat, the annual mean concentration of suspended solids returned to pre-treatment levels in 5–6 years. Concentrations of mineral nitrogen, especially NH4-N, increased while the concentration of organic nitrogen decreased after ditch network maintenance. These changes persisted for the whole six-year period. The overall effect of these changes resulted in a slight lowering of total dissolved nitrogen concentrations. With the exception of a few sites, runoff water pH increased after ditch maintenance and remained high during the 6-year period. Concentrations of DOC decreased at all sites after ditch maintenance and was still at a low level after six years. Concentrations of base cations (Ca, Mg, K, Na) increased significantly after ditch maintenance and were still high after six years. High concentrations of Al and Fe immediately after the digging operations were observed in a few sites. Concentration of total dissolved P did not change much and tended to decrease rather than increase.
  • Joensuu, Forestry Development Centre Tapio, Soidinkuja 4, FIN-00700 Helsinki, Finland Sähköposti: ei.tietoa@nn.oo (sähköposti)
  • Ahti, Sähköposti: ei.tietoa@nn.oo
  • Vuollekoski, 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 (sähköposti)
  • Lauhanen, Sähköposti: ei.tietoa@nn.oo
  • Saarinen, Sähköposti: ei.tietoa@nn.oo

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