Artikkelit kirjoittajalta Hannu Mannerkoski

The paper describes an apparatus for indicating the water level in ground water wells. It gives a sound signal whenever water completes the electrical circuit between the two leads of the probe. It is inexpensive and easy to use. The level of the water surface indicated by a piezoelectric buzzer thus leaving the user free to observe the depth scale.

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

The article presents results of an experiment in which different sowing and planting methods were compared. The experi-ment was carried out in two experimental areas in Central Finland, the Lylynsuo and the Nuijaneva. The Lylynsuo area has been drained in 1969 and its pre-drainage peatland site type was an ordinary sedge bog. The Nuijaneva area has been drained in 1963 and its site type was a small-sedge bog. The experimental layout was the same in both areas: four planting and four sowing methods on five blocks. An experimental unit consisted of a pair of rows with 100 transplants or sowing spots. The methods used were. 1. Planting on intact peat surface 2. Planting on top of the furrow ridge made by a reforestation plow (see Fig. 1) 3. Planting on the side of the ridge nearest to the furrow 4. Planting on the other side of the ridge 5. Sowing on intact peat surface 6. Sowing on a 50 x 50 cm2 spot, from where the living moss had been removed 7. Sowing on a foot-pressed spot, on chopped peat spread out with Kopo spiral trencher 8. Sowing with sowing machine (see Fig. 2). The afforestation was made with Scots pine in the spring 1969. After planting and sowing, spot fertilization (30 g/trans- plant or sowing spot) was applied with compound fertilizer (15 % N, 25 % P2O5, 10 % K2O). Living transplants and sowing spots with seedlings were counted in the autumn 1969, in the spring 1970, in the autumn 1971, and in the autumn 1974. The height and the height growth of the transplants and seedlings were measured in 1971 and 1974, the height of the seed-lings in the machine-sown group only in 1971. The results are presented in the Figures 3— 5. Planting was successful with all the methods applied, with no significant differences between the methods. Sowing succeeded better in the Nuijaneva area than in the Lylynsuo. As can be seen, the results of sowing correlate with the competition from the surface vegetation, which is greater in the Lylynsuo area. The transplants were significantly higher and their height growth greater in the three turf planting methods (2—4) than in the method of planting on intact peat surface. Height growth of seedlings was the best on the chopped peat (method 7) and the poorest on the intact surface. Results from the two experimental areas are quite similar. Taking into account the age diffe-rence of the seedlings and the transplants, the seedlings are either growing almost as well as the transplants or are only a year or two behind in development.

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

The results of plant coverage analyses carried out in summer 1976 on a peatland drained in 1950 are presented in this article. The results from earlier analyses (1950, -52, -54, -59, -63 and -70) have earlier been published (Mannerkoski 1970). The tree stand characteristics measured in 1961, -66 and -73 are also presented (Table 1). The results for the plant coverage analyses (Table 2, Fig. 2 and 3) have been obtained from five plant coverage sample plots. The tree stand consists mainly of Scots pine and has grown well. The mean stand increment during the period 1966—73 was 5.8 (A26) and 4.0 (A28) m3/ha/yr calculated as the difference between the volumes with bark. There was a lot of Norway spruce and birch seedlings growing in the stand but only few pine seedlings were found (Fig. 1). The most important changes which had taken place in the coverage of different plant species since 1970 were as follows: Dicranum had increased and Sphagnum recurvum had decreased on plots 1—3, Sphagnum robustum had increased on plots 3 and 4 and Vaccinium oxycoccos had decreased on all the plots. Aulacomnium palustre, Eriophorum vaginatum and Carex canescens had completely died out. It can be clearly seen from figures 2 and 3 that the increase in Vaccinium vitisidaea has stabilised and that Polytrichum commune is still present in large numbers. It appears that the changes in the coverage of different plant species are dependant on the effect of shading and competition by the tree stand. Only those species with the greatest moisture requirements have disappeared within the first few years after draining as a result of drying out of the surface peat (cf. Mannerkoski 1970).

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

The results of an experiment concerning the artificial regeneration of a pine stand growing on old drainage area are presented in this article. The area was clear-cut during the winter 1970-71. Six experimental plots were laid out on the area in summer 1971, three of them being control plots. Soil preparation was carried out on the remaining three plots. A tractor digger was used to make turf hummocks by lifting scoop-fulls of peat and placing them upside down on the ground at two meter intervals. The hummocks were then compressed by the digger scoop. In spring 1972 Scots pine transplants (2+1 years) were planted out on the hummocks and on the untreated peat surface of the control plots. The survival rates of the transplants are presented in Table 1. The average height and height growth of the surviving plants in different years can be seen in Table 2. The transplants growing on the hummocks have survived and grown better than those on the untreated peat surface. Eriphorum vaginatum has spread vigorously on the untreated peat surface of the control plots and has tended to check the growth of the seedlings. Damage caused by frost heaving was not observed. This planting method thus appears to be a useful soil preparation technique in the regeneration of old drained stands.

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

The article presents results of tensiometer measurements in peat soils. Measurements have been taken both in the field and in the greenhouse. The plots in the field experiment represented different stages of drainage in ordinary sedge bog. Plot 5 was in a virgin state, plot 6 had been drained in 1967, and plot 3, in the 1930's. Each plot had one tensiometer at each of the three measuring depths. (5, 20 and 40 cm). In the field the depth of the ground water table was also measured using self-registering gauges. In the greenhouse experiment the water table in the soil samples was artifically regulated by raising it straight from the deepest level to the topmost level, and lowering it after every 2-3 days (see Fig. 3). The results are presented in figures 1-4. The soil water tension and hydrostatic pressure values obtained with tensiometers show a close correlation with those concerning the ground water table in case when the measuring unit has been near the water table or below it. Evapo-transpiration and rainfall caused a variation to the relationship between the water table and soil water tension at the depth of 5 cm, particularly when the water table was deep (30-40 cm) (Fig. 2). The effect of evapotranspiration can be seen also in the results of the greenhouse experiment (Fig. 4). In this experiment the effect of the rise of the water table was not as great as expected. The reason for this may be too short a time for levelling (2 days). The results show that tensiometers can be used also for measurements on the depth of the ground water table if it has a sufficiently assu-rate manometer and if the measuring unit is kept near or below the ground water table.

• Laine, Sähköposti: ei.tietoa@nn.oo
• Mannerkoski, Sähköposti: ei.tietoa@nn.oo

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

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

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

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

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

• Mannerkoski, Sähköposti: ei.tietoa@nn.oo
• Seppälä, Sähköposti: ei.tietoa@nn.oo