Kimmo Tolonen

Turvekertymistä ja turpeen tilavuuspainoista kolmessa eteläsuomalaisessa keidassuossa

Tolonen K. Turvekertymistä ja turpeen tilavuuspainoista kolmessa eteläsuomalaisessa keidassuossa.

Tiivistelmä

The annual deposition of peat (dry matter accumulation) was investigated in three South Finnish raised bogs on the basis of bulk density determinations combined with datings of peat layers by pollen analysis, radiocarbon age measurements and by moss increment dating method (see Pakarinen & Tolonen 1977). The range of accumulation rates varied in Kaurastensuo, Lammi (61° 02° N) from 25 to 43 g/m2, yr (Table 2); in the same site the current primary production was estimated to be about 420 g/m2 (Table 1). In an other bog (Munasuo, 60° 37'N) the average long-term dry matter accumulation ranged from 40 to 48 g/m2 (Table 3). Preliminary results in these bogs show that some 6—16 percent of annually produced organic matter was accumulated as peat (vegetation type: Dwarf shrub rich S. fuscum community). The bulk density in virgin Sphagnum peats, which are only slightly decomposed, was very low in the bogs investigated (20—50 g/dm3). This value can be often low (only a little greater than above mentioned) in special cases in highly humified peats, too. The high water content of peat and a low autocompaction degree can explain this feature. — After the drainage of the peat-lands a compression obviously very soon results a distinct increase in the bulk density. In natural conditions peat layers originated from hollows have much greater autocompaction (cf. Aaby & Tauber 1974) than the peats of hummock and intermediate surface (lawn). This difference comes still clearer when one compares the bulk density values of living Sphagnum layers with corresponding peat (Table 4). When estimating the peat resources in terms of dry matter, the great variation in «real bulk density» values in virgin peatlands, and factors determining it should be considered.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1977

Katselukerrat 1261

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