Ilkka Markkula

Maaperäeläinten vertikaalijakauma luonnontilaisella ja ojitetulla keidasrämeellä

Markkula I. Maaperäeläinten vertikaalijakauma luonnontilaisella ja ojitetulla keidasrämeellä.

Tiivistelmä

Vertical distribution of soil mites, springtails and enchytraeid worms was studied in virgin and forest-improved parts of a raised bog Laaviosuo in Lammi in 1975 and -76. The forest-improving practices were drainage in 1966 and NPK-fertilization in 1970. The drainage had lowered the ground water table by 10—15 cm (Table 1.). In both the virgin and the drained study sites, the water table was deeper in the Sphagnum /uscu/n-dwarf shrub-dominated hummocks than in the S.angustifolium-Eriophorum-dominated hollows. Those micro-relief structures were considered as separate microhabitats. The ground water table was closely correlated with the topsoil moisture and it also stated the lower limit of aerobic conditions in the peat. In the hollows the animals were relatively more restricted to the uppermost soil layers than in the hummocks (Fig. 1). This was most probably due to the high water table and thin aerobic layer in the hollows. The distribution of enchytraeids and prostigmatid mites had changed after drainage so that a greater portion of animals lived in the deeper soil layers in relation to the virgin site. In the other animal groups no such difference was observed. The vertical distribution of enchytraeids and ori-batids is plotted against the ground water table in Figs. 2 and 3. The very significant correlations result from great differences between the microhabitats. Inside the microhabitats there were no close correlations (Table 2). In the samples taken from frozen soil most enchytraeids and oribatids were usually found in the deeper soil layers (Tables 3 and 4). This most probably resulted from active migration to avoid coldness. However, in the virgin site hollows the oribatids stayed in the topsoil, possibly because the waterlogged and anaerobic conditions in deeper layers are unsuitable for their overwintering.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1981

Katselukerrat 2447

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