Eero Paavilainen

Rauduskoivun ja männyn ensi kehitys rimpisellä lettoturpeella

Paavilainen E. Rauduskoivun ja männyn ensi kehitys rimpisellä lettoturpeella.

Tiivistelmä

In this study samples of both flark and forest peat from nutritionally similar sites were compared. Flark peat was found to be richer in nearly all nutrients, including the exchangeable ones, than the forest peat (Table 1). The most important reason for the difference may be that the trees and ground vegetation on a pine fen have taken up and retained a considerable part of nutrients. Microbes may, however, have fixed more nutrients on flark fen than on pine fen, for there were four times as many aerobic bacteria in flark peat than in forest peat. The peat required for the experiments came from Alajärvi fen in the Kivalo experimental area belonging to the Forest Research Institute. Peat was taken from two points, 30 metres apart. One sampling point was located on a flark fenlike bog and the other on a pine fen. Peat from the former will be called flark peat, from the latter forest peat. Thirty pots were filled with two peat types. Three pine seedlings grown in unfertilized garden peat were planted in every other pot and birch seedlings in the rest of the pots. Pine seedlings were grown in their pots in a greenhouse for about 12 moths and birch seedlings for about 10 months. At the end of the experiment the shoots were weighed, the length of roots measured and the root tips counted. Every fifth birch root branch in each pot was measured; while each pine root from every other pot was chosen for measurements. Results from the analysis lead to the assumption that flark peat, because of its richer nutrient content, may be better than forest peat as a substrate for the growth of Betula verrucosa and Scots pine. The final measurements showed that the growth of birch shoots and roots was much stronger on flark than on forest peat (Table 2). The growth of pine shoots showed a similar trend, although the difference was smaller. The investigation also included the forming of mycorrhizae in seedlings and corresponding nutrient uptake. A microscopic study of the slices from root tips revealed a rather weak ability of birch and pine to form mycorrhizae (Fig. 1). There^ were no marked differences in mycorrhizaf development of seedlings grown on flark or forest peat. Scanning electron microscopy showed that some root tips were enveloped by mycelium and that pines grown on flark peat displayed unidentified cell formations (Fig. 2). When comparing the influence of peat extracts and mixtures of nutrient solution on the growth of mycorrhizal fungi, it was detected that a fungus important for birch, Paxillus involutus, grew better in a solution containing extract from forest peat rather than flark peat (Table 3). Tricholoma flavo-brunneus yielded the opposite result in two experiments, in one of which the difference was statistically significant. The fungi important for pine, Cenococcum grani-forme and Boletus variegatus, grew better in a nutrient solution containing extract from forest peat. The growth of other involved mycorrhizal fungi (Amanita muscaria umbrina, E-57) was not significantly dependent on peat types. The examination of seedlings grown in 32P isotope solution showed that the phosphorus uptake was better from a pure nutrient solution than from a solution containing either of the two peat extracts (Table 4). The extract from flark peat, as compared to that of forest peat, harmed the phosphorus uptake of birch less; whereas pine reacted in the opposite way. Pine could on a peat substrate, however, take up phosphorus, applied at watering, better from flark peat than from forest peat. According to the results, peat from a flark fen was a good substrate for the initial development Betula verrucosa. The initial development of Scots pine was relatively much weaker on this peat substrate. The experiments utilizing peat extracts even imply that peat from a flark fen may contain, in its natural state, substances that harm the growth of mycorrhizal fungi on pine and the nutrient uptake of seedlings. More investigations, however, are necessary for any final conclusions.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1978

Katselukerrat 1144

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