Artikkelit kirjoittajalta Eero Paavilainen

The development of peatland forests over a 10-year-period (1977-1987) in Satakunta Forestry Board District, Western Finland, is presented, based on the results of the 7th and 8th National Forest Inventories. Over this period the amount of peatlands classified as forest land (MAI over bark over a 100 years rotation ≥ 1 m3ha-1) and the total volume and increment of peatland forests considerably increased, mainly as a result of drainage. Keywords: Forest drainage, inventory, peatland forests

• Paavilainen, Finnish Forest Research Institute, P.O. Box 18, SF-01301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo

The report is part of the refertilization project started in 1972 in the Department of Peatland Forestry, the Finnish Forest Research Institute. Nitrogen, as well as phosphorus and potassium, are required in the refertilization of oligotrophic pine bogs. The need for nitrogen is less on fertile pine swamps, although in some experiments moderate fertilization with nitrogen in addition to PK gave the greatest stand growth increment. The use of micronutrients, especially boron, is recommended in the refertilization of fertile pine swamps. Methods for determining the need for nitrogen and micronutrients in refertilization should be further developed.

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

The effect of the first fertilization (PK, NPK) on the plant biomass and nutrient cycle of a drained dwarf shrub pine swamps was only barely noticeable after thirteen growing seasons. NPK refertilization increased the annual biomass production and the amount of litter. The macronutrient content of the tree crop and the field layer vegetation increased, while the copper and boron content decreased after refertilizati-on. NPK fertilization also increased the amount of nutrients in the litter, and accelerated the decomposition of cellulose test slips and needle litter. The individual nutrient contents on a nitrogen-rich peat soil were clearly higher in, the birch litter than in the pine litter. Refertilization, especially with NPK and micro-nutrients, in most cases increased the nutrient contents and amount of litter.

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

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.

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

The aim of the study was to clarify, in what degree nitrogen is needed when fertilizing drained pine swamps in North Finland. Particular interest was laid on the fertilization of peatland types rich in nutrients. Further, the dependence of the fertilizer-induced growth reaction on ditch spacing and thickness of peat layer were considered. The growth reaction resulting from fertilization was estimated by measuring the annual height and radial growth on differently treated experimental plots and by using analysis of covariance. Further factors considered in the analysis were peatland type and its so-called sub-class, depth of peat layer, ditch spacing, age, height and diameter of the sample trees at the time of fertilization, and sample tree growth before fertilization. When fertilizing tall sedge pine swamps and more fertile pine swamps for the first time in Ostrobothnia, Kainuu and southern Lapland nitrogen deficiency seems not to be a minimum factor as regards the growth of Scots pine. On the other hand, it seems necessary to include nitrogen in the first fertilization treatment on less fertile pine swamps than mentioned above. According to the study, the growth of Scots pine subsequent to fertilization appears to be the better, the narrower the ditch spacing and the thinner the peat layer. More detailed information has been published by Paavilainen and Simpanen (1975).

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ei.tietoa@nn.oo

• Paavilainen, Sähköposti: ep@nn.fi
• Päivänen, Sähköposti: juhani.paivanen@helsinki.fi
• Saarinen, Sähköposti: ms@nn.fi