Suo - Mires and peat vol. 26 no. 5 | 1975

This study is a sequel to papers previously published on the possibilities of extending the period of planting Scots pine (Pinus silvestris L.) on drained open peatlands over the entire growing season (Päivänen 1968, 1971), The study was carried out using the same plots as in the experiments described in the above-mentioned papers. This final investigation was carried out in order to find ou t whether the differences recorded in the previous studies had been leveled out or accentuated when 9—11 growing seasons in the field had elapsed since planting. As the smallest unit which the study was based on was a single row of young trees, the study must be considered as being completed by now. This is because the interactions between adjacent tree rows will become significant as soon as the crowns and root systems get closed. Mortality still increased by a few per cent units during the last 5—6 growing seasons. This increase, however, was of similar magnitude irrespective of the planting date. In the mean height of the trees, on the other hand, the differences caused by differences in the planting date were clearly visible in the final inventory (Figs. 1—3). The differences in height development had even become accentuated by the time of the final inventory, 9—11 growing seasons after planting. A clear correlation was observed, in the case of all experimental members, between the mean heights recorded in the final inventory and that carried out after the trees had spent four growing seasons in the field (Fig. 5). According to the results obtained the season-alness of planting work can be decreased on drained peatlands by extending the planting season of pine till the turn of the month between July and August. Plantings performed in the fall usually proved slightly less successful than those carried out in June and July. The nursery ought to be situated close to the areas to be planted since the handling and transportation of unrooted plants during the growing season must take place with extreme care.

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

The study showed that the levels of copper, boron, zinc and cobolt in organic soils are in general lower than those in mineral soils. However, for manganese it was quite the opposite. There were no clear differences found between the levels of molybdenum and selenium in different soil types. Trace element levels in different geographical areas varied considerably. Since the results of this study indicate that the trace element situation in agricultural soils appears to be following an unfavourable trend, the situation must be closely watched by means of cultivation studies. Good yields must be mainted if the food requirements of people and livestock are to be met.

• Kurki, Sähköposti: ei.tietoa@nn.oo

During the last five years a number of foresters and research workers in Finland have noticed the increasing occurrence of a growth distur-bance in 10—15 year old peatland stands. This phenomenon is referred to as "eskimosis" in this paper. The symptoms do not resemble those of any of the known nutrient deficiencies and as far as we know it does not appear to be caused by insects or fungi. The symptoms of eskimosis in Pinus silvestris are as follows; — young samplings have long branches — apical dominance is lost — lammas growth is common — terminal shoots may become branched — needle lenghts vary within wide limits — elongation growth is suppressed — dark green colouring and sturdy external appearance of saplings Apparently 1—2 years after these almost invisible symptoms first appear, eskimosis kills the apical parts of the "infected"" trees, usually from one to three whorls, during late winter (die back). Some trees develop 2—3 leaders without any additional symptoms, but usually eskimosis is repeated year after year causing cessation of height growth, giving the tree a flat-topped appearance with plenty of dead needles distributed throughout all parts of the trees. At this stage of eskimosis, resination of the buds, necrotic spots on the needles and browning inside the shoots proceeding from the apical parts, are typical secondary symptoms. After some years the cambial growth may also be suppressed as a result of the decreased amount of green needles. Eskimosis results in thick-stemmed and stunted trees which very often die. An investigation programme has been started by the Department of Peatland Forestry, the Finnish Forest Research Institute, and some preliminary results are published in this paper. Eskimosis may infect pines, spruces and birches on drained peatlands as well as on mineral soils. Phosphorus fertilization often increases the likelihood of eskimosis developing. The first attempt to cure eskimosis, was carried out in a drained spruce stand, by fertilizing with micro-and macro-nutrients. The greatest increase in radial growth was achieved with NP fertilization, although the spruces survived even without any fertilization. Boron had a slightly positive effect on visible symptoms. Eskimosis was apparently caused by P-rich litter from the previously felled pine stand which had been fertilized with phosphorus some years prior to felling. The young spruce stand lost its shelter stand and subsequently received much easily soluble phosphorus from the P-rich litter. The largest known eskimosis area lies at Kivi-suo Experimental Fields, Leivonmäki, in pine plantations established in 1959. Kivisuo, Exp. 1^ lay-out, 4x4x4 NPKwith two replications, planting spacing 2 m, ditch spacing 22 m, earlier used as a drying field for hydro peat, originally an open Sphagnum bog with rimpis, fertilization in 1959, refertilization 1968. During refertilization, the plots were divided into three parts; a = broadcast fertilization, PK(0-17-15) 500 kg/ha b =spot fertilization. PK(0-17-15) 50 g/ sq.m c = control A couple of years after refertilization was carried out, eskimosis appeared. It seems that eskimosis is largely a result of the original micro-relief of the bog and is further increased by the highest P and K levels (eg. Huikari and Paarlahti, 1973). Another investigation was carried out in 1975 with the following results: the elongation growth of the trees was decreased most on plots which received broadcast refertilization and least on the control plots (Fig. 1.). The situation was about the same in Experiment V which was spot fertilized in 1959 (spot size 0,25 sq.m) and refertilized in 1966 in a similar way as exp. 1. Eskimosis also appeared soon after refertilization. A decrease in tree heights induced by eskimosis was observed (Fig- 2). Experiments under greenhouse conditions using substrate taken from sites where eskimosis is prevalent have shown that this Scheuchzeria-rich peat is deficient in N, K and B even after previous site treatments with NPK and PK at high levels. This may be the solution to the problem at Kivisuo. It will require perhaps another 2—3 years to confirm this before our micronutrient experiments will provide us with the final details. "

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

Total contents of various trace elements in Finnish soil types are presented. The tendency for the trace element content to decrease with increasing particle size in mineral soil is discussed. It is believed to be associated with the geological origin of the soil matrix and especially with the relative resistance to weathering of the minerals from which the trace elements are derived. Fine textured soils are likely to have been derived from more easily weatherable rocks and minerals than coarse soils, in which resistant minerals like quartz are known to be the main constituents. On the other hand, those minerals containing the trace elements in question are among the most easily weatherable, while quartz is likely to contain none of these elements. The characteristic distribution of 13 trace elements in two peat profiles X', as well as the low content of most elements in peats as compared with those in mineral soils are explained as a result of the transport of elements by plants from lower strata: The trace elements can be considered as originating from the mineral soil underlying the peat. Plants which grow and then decay, first on the mineral soil and later on the peat, obtain the trace elements from the subsoil and, when dying, cause these elements to accumulate on the surface layer. When the peat layer becomes thicker contact between the plant roots and the mineral subsoil is gradually reduced until finally the bulk of the roots are no longer in contact with the mineral soil. Subsequendy, the plants lift up elements from the lower peaty layers of the profile, thus decreasing the element content of the lower parts of the peat. For this reason, the trace element content in the peat profile decreases as the peat thickness increases; extreme cases of this development are the "raised bogs" of Sphagnum peat which are known to have a very low content of all the nutrients. The relatively high concentration at the immediate surface is obviously a result of the elements lifting activity of the most recent generations of plants; the elements have been lifted to the surface and are awaiting removal by future generations of plants. x) Orig. pubi.: Sillanpää, M. 1972. Distribution of trace elements in peat profiles. Proc. 4th Intern. Peat Congr. I-IV: 185-191.

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

The article deals with the oligotrophic-eutrophic and ombrotrophic-minerotrophic gradients in peatlands. The use of these terms in Finland, Sweden, the Soviet Union, Central Europe, Canada and England is briefly reviewed. In the case of peatlands, the concept of eutrophy, as defined by most authors, implies high pH, high levels of calcium and nitrogen, but its relationship to phosphorus and potassium levels (which greatly affect the tree growth and productivity) is not so clear. It is important to make a distinction between trophic series related: (1) to primary production, and (2) to pH (Ca)gradient. For the former, the terms oli-go-, meso- and eutrophic seem appropriate (as in the case of limnology); for the latter, the following four categories could be used: ombrotrophic, weakly-, moderately- and strongly minerotrophic. Apparently some authors have also used the terms soligenic or rheotrop-hic as synonyms for minerotrofic.

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