Tapio Lindholm

Keidasrämeen mätässammalten vuotuinen pituuskasvu Lammilla EH

Lindholm T. Keidasrämeen mätässammalten vuotuinen pituuskasvu Lammilla EH.

Tiivistelmä

The annual height growth of three hummock moss species was studied in two neighbouring ombrotrophic raised bogs in Lammi commune, southern Finland (N 61° 02', E 24° 58'). The species were the dominant species of the hummocks: Sphagnum fuscum, Polytrichum strictum and Sphagnum rubellum. The annual increment was measured backwards for seven years (Figs. 1—3) by the "innate markers" occuring of the cyclical patterns of the growth (Maimer 1962, Pakarinen & Tolonen 1977). The samples were taken from c. 30 different places in different parts of the bogs. The mean height growth was 10.8±l.5 SD/a in Polytrichum strictum, 11.6 mm ±0.9 SD/a in Sphagnum fuscum, and 10.9 mm ±l.l SD/a in Sphagnum rubellum. The annual variation was quite small, whereas the variation between microhabitats was great. In high hummocks the growth of P. strictum and S. rubellum seems to diminish by years due to increasing distance to the water table. S. fuscum seems to be more tolerant against drier conditions. It also grows slightly better than the other two species. This may be the reason why S. fuscum is the dominant species on Finnish raised bog hummocks. The "innate marker"" method does not allow measurements of the annual increment if the moss shoot growth is very slow in the hummock and thus may give slightly too high growth estimates. Similar values of annual increment of hummock peat have been observed also in other studies (Borggreve 1889, Saarinen 1933, Hornets 1974, Pakarinen 1978). The annual variation in the growth was not investigated in the earlier studies, where results are mainly means of many years' growth. It is obvious that in ombrotrophic raised bogs the hummock mosses cannot grow more than 10—12 mm/a in our environ-mental conditions. In other conditions, eg. in Great Britain (Clymo 1970), and also in better sites in Finland (author's own field observations) the annual growth rate can be much higher. "

Vastaanotettu 31.10.2017 Julkaistu 1.1.1979

Katselukerrat 444

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