Marjut Karsisto

Maanparannustoimenpiteiden vaikutuksista orgaanista ainetta hajottavien mikrobien aktiivisuuteen suometsissä. Osa I. Pohjaveden etäisyyden ja NPK-lannoituksen vaikutus Vilppulan ja Kivalon rämeellä ja korvessa

Karsisto M. Maanparannustoimenpiteiden vaikutuksista orgaanista ainetta hajottavien mikrobien aktiivisuuteen suometsissä. Osa I. Pohjaveden etäisyyden ja NPK-lannoituksen vaikutus Vilppulan ja Kivalon rämeellä ja korvessa.

Tiivistelmä

The aime of the study is to determine whether the decomposition of organic matter and the activity of different groups of micro-organisms has changed in peat-lands where the ground-water table has been maintained at different depths for a considerable length of time. The study has been carried out in sample plots situated on Scots pine and Norway spruce swamps where the groundwater table has been maintained at depths of 10, 30 and 70 cm since 1960. The annual growth of the trees has been followed since the time when the experiment was established. It has thus been possible to examine the connection between tree growth and the numbers of different types of bacteria and the rate of decomposition of the organic matter. Experiments with NPK fertilizer were established in 1961—1962 on plots where corresponding ground-water table regulation had been carried out. The plots in North Finland were refertilized in 1965, and those further to the south in 1967—1969. Intensification of drainage on the sample plots established on spruce swamps has produced a considerable increase in stand growth (Fig. 1). Decomposition of cellulose in the peat has also increased (Fig. 2). Cellulose decomposition on the plots which have been efficiently drained is effective down to a depth of at least 50 cm. Fertilization increased stand growth most on those plots on the spruce swamp where the ground-water table had been maintained at a depth of 10 cm from the surface. Cellulose decomposition also became more effective on these plots. The nutrient reserves in peat which has been efficiently drained, have possibly been sufficient without any fertilizer addition. Fertilization has had a strong effect on stand growth on the pine swamps, the best results being obtained with a drainage depth of 30 cm. Fertilization has also had the strongest effect on cellulose decomposition in the plots on pine swamps where the ground-water table has been maintained at a depth of 30 cm. The numbers of aerobic, ammonification and proteolytic bacteria in the surface layer of the unfertilized peat have been the greater, the deeper the ground-water table (Fig. 5). Intensifying drainage has had the strongest effect on the number of ammonification bacteria. Fertilization, similarly, had the strongest effect on the number of ammonification bacteria. In other words, the activity of both the trees and the bacteria has been limited by a lack of nutrients, which fertilization has alleviated. Although drainage makes the conditions in the peat more aerobic, the number of anaerobic, bacteria has not decreased as the efficiency of drainage increased. Generally speaking, the higher the level of bacterial activity, the better the tree growth. Following changes in the number of different types of bacteria provides information about the decomposition of organic matter in the peat. However, this is not sufficient and chemical analyses are also required.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1979

Katselukerrat 1222

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