Suo - Mires and peat vol. 30 no. 1 | 1979

The annual height growth of three hummock moss species was studied in two neighbouring ombrotrophic raised bogs in Lammi commune, southern Finland (N 61° 02', E 24° 58'). The species were the dominant species of the hummocks: Sphagnum fuscum, Polytrichum strictum and Sphagnum rubellum. The annual increment was measured backwards for seven years (Figs. 1—3) by the "innate markers" occuring of the cyclical patterns of the growth (Maimer 1962, Pakarinen & Tolonen 1977). The samples were taken from c. 30 different places in different parts of the bogs. The mean height growth was 10.8±l.5 SD/a in Polytrichum strictum, 11.6 mm ±0.9 SD/a in Sphagnum fuscum, and 10.9 mm ±l.l SD/a in Sphagnum rubellum. The annual variation was quite small, whereas the variation between microhabitats was great. In high hummocks the growth of P. strictum and S. rubellum seems to diminish by years due to increasing distance to the water table. S. fuscum seems to be more tolerant against drier conditions. It also grows slightly better than the other two species. This may be the reason why S. fuscum is the dominant species on Finnish raised bog hummocks. The "innate marker"" method does not allow measurements of the annual increment if the moss shoot growth is very slow in the hummock and thus may give slightly too high growth estimates. Similar values of annual increment of hummock peat have been observed also in other studies (Borggreve 1889, Saarinen 1933, Hornets 1974, Pakarinen 1978). The annual variation in the growth was not investigated in the earlier studies, where results are mainly means of many years' growth. It is obvious that in ombrotrophic raised bogs the hummock mosses cannot grow more than 10—12 mm/a in our environ-mental conditions. In other conditions, eg. in Great Britain (Clymo 1970), and also in better sites in Finland (author's own field observations) the annual growth rate can be much higher. "

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

The occurrence of different types of damaging agent in 9 Scots pine seedling stands established on peatlands and subsequent effect on the initial development of the seedlings was examined in the study. The results concern only those parts of the seedling stands, many of them rather extensive ones, which were in a poor condition. About 36 % of the seedlings had either died or were incapable of further development as a result of damage by various agents. The most commonly occurring insect pests were pine weevils (Pissodes spp., especially P. pint L.), damage being caused by both larvae (in seedlings weakened before) and imagos. Damage caused by Petrova resinella L. which makes grooves in the seedlings that remain unhealed for a long time, was found to some extent. Damage caused by Hylobius-species was very rare. Damage caused by Diprionidae and Cryptocephalus pini L. was found to some extent but it was very slight. Of the fungal deseases, pine stem canker (Scleroderris lagerbergii Gremmen) was found to be a serious damaging agent. Snow blight {Phacidium infestans Karst.) occurred relatively abundantly, but because most of the seedlings had already grown higher than the snow cover, the effect of this fungus was generally only slight. Stems damaged by pine stem rust (Melam-psora pinitorqua Rostr.) were found to some extent, the damage being only slight. Abiotic damage was rather common on the seedlings. Snow had broken branches and pressed the seedlings down, thus weakening them and making them more susceptible to subsequent damage. Rather a lot of the seedlings (22 % of them) were suffering from bark damage (channels, compression, drying out of the bark), which obviously often presupposed damage by pine stem canker and pine weevils. Needle yellowing, symptomatic of nutrient deficency, was also found in part of the areas. Most of the damage noted in this study was of the same kind as that found in Scots pine seedling stands established on mineral soils sites in Northern Finland.

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

In this article we survey the pyrolysis of some solid domestic fuels in the lowered pressure, which completes the picture of the pyrolysis. Also, the possible comparison between the pyrolysis of the domestic fuels and the research methods have been rendered. The lowered pressure has a significant effect on the pyrolysis, because part of the polymerization and the coking are hindered. Up to the 650 K the pyrolysis seems to occur as in the nitrogen gas but thereafter no coking appears but the thermal decomposition proceeds. The remaining part of the reaction equals to the ash amount obtained after the reaction in the mixed gas. It is also obvious, that the particle size plays an important role in the pyrolysis in the lowered pressure. This can be seen from the inconsistent results presented in the literature. The substances under investigation are mixtures of several organic compounds whose composition or even an average molecular mass is unknown. The calculation methods employed here are based on the approximations which are valid for the simple reactions of the compounds with known structures. Their application to the unknown reactions is strongly criticized. If we perform the measurements in equal conditions and interprete the results as pseudo constants, they have, however, significance if the average properties of the pyrolysis of different substances are compared. Finally, since the pyrolysis of the organic matter completely occurs in the lowered pressure, this may have meaning when the refining processes are developed.

• Tummavuori, Sähköposti: ei.tietoa@nn.oo
• Venäläinen, Sähköposti: ei.tietoa@nn.oo
• Nyrönen, Sähköposti: ei.tietoa@nn.oo