Hannu Mannerkoski

Puuston ja pintakasvillisuuden kehitys ojituksen jälkeen saraisella suolla

Mannerkoski H. Puuston ja pintakasvillisuuden kehitys ojituksen jälkeen saraisella suolla.

Tiivistelmä

The results of plant coverage analyses carried out in summer 1976 on a peatland drained in 1950 are presented in this article. The results from earlier analyses (1950, -52, -54, -59, -63 and -70) have earlier been published (Mannerkoski 1970). The tree stand characteristics measured in 1961, -66 and -73 are also presented (Table 1). The results for the plant coverage analyses (Table 2, Fig. 2 and 3) have been obtained from five plant coverage sample plots. The tree stand consists mainly of Scots pine and has grown well. The mean stand increment during the period 1966—73 was 5.8 (A26) and 4.0 (A28) m3/ha/yr calculated as the difference between the volumes with bark. There was a lot of Norway spruce and birch seedlings growing in the stand but only few pine seedlings were found (Fig. 1). The most important changes which had taken place in the coverage of different plant species since 1970 were as follows: Dicranum had increased and Sphagnum recurvum had decreased on plots 1—3, Sphagnum robustum had increased on plots 3 and 4 and Vaccinium oxycoccos had decreased on all the plots. Aulacomnium palustre, Eriophorum vaginatum and Carex canescens had completely died out. It can be clearly seen from figures 2 and 3 that the increase in Vaccinium vitisidaea has stabilised and that Polytrichum commune is still present in large numbers. It appears that the changes in the coverage of different plant species are dependant on the effect of shading and competition by the tree stand. Only those species with the greatest moisture requirements have disappeared within the first few years after draining as a result of drying out of the surface peat (cf. Mannerkoski 1970).

Vastaanotettu 31.10.2017 Julkaistu 1.1.1976

Katselukerrat 1232

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