Harri Vasander

Luonnontilaisen keidasrämeen sekä lannoitetun ojikon ja muuttuman ravinnevarat

Vasander H. Luonnontilaisen keidasrämeen sekä lannoitetun ojikon ja muuttuman ravinnevarat.

English title: Nutrients in an ombrotrophic bog ecosystem in the virgin state and after forest-improvements

Tiivistelmä

The study was carried out in three ombrotrophic bog sites, a virgin pine bog (Kaurastensuo), a site with NPK-fertilization in 1970 and a site with NPK-fertilization in 1978 (plot no. 8 in Reinikainen & Lindholm 1980; Fig. 1). Samples for nutrient analysis were taken in October 1979, and the following total nutrients were determined: N, P, K, Ca, Mg, Cu, B. The amount of plant biomass and production was calculated according to Vasander (1981). The surface peat (0—20 cm) was very poor in nutrients compared to earlier observations in pine bog sites. In the site NPK -1978 there were probably still hails of slow-soluble fertilizers as the amounts of P and Ca were high in the ground layer (Fig. 1). The amounts of nutrients were usually proportionally higher in the field layer vegetation and the needles than were their proportions of biomass and production (Fig. 1, Table 2). However, there was little B and Cu in the needles except for in the site NPK-1978 (Fig. 1). According to the estimated nutrient budget (Table 3), 23.7 kg/ha K corresponding to 43 % of the added potassium was found neither in the surface peat nor in the vegetation. If it all had leached, the annual loss would evenly distributed be 2,63 kg/ha. This loss is of the same magnitude as leaching found in earlier studies of fertilized bogs, but appr. twice the value of virgin bogs. The budget was positive for phosphorus and nitrogen mainly because of the compression and increasing bulk density of the peat in NPK-1970. In the last years the supply of N and P has not been sufficient to maintain post-fertilization pine growth level.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1981

Katselukerrat 1130

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