Suo - Abstracts of Vol. 48, 1997

Nineteen words, describing different types of mires and morphological and topographical features in mires, used in the dialects of northern Finlad are described in this article. Several of these words have been adopted from the indigenous Sami people, who live in the northernmost part of Finland, Sweden and Norway. Best known of these Sami words are aapa and palsa, which are internationally used mire terms.

Key words: dialect, loan words, mire words, North-Finland, Sami language

Remote sensing methods used together with the Geographical Information Systems (GIS) open new possibilities also in vegetation area studies. In this paper we apply these methods to discriminate mire site types. We studied surface temperatures in Isoneva mire, western Finland (60° 40' N, 21° 59' P), using Thermal Infrared (TIR)-images. The vegetation composition data were based on previous field studies. Surface temperature samples for four different mire site type and one upland forest site type were taken, and the distributions of their surface temperatures were analyzed. The results indicate that there are discernible surface temperature differences between different vegetation types.

Key words: GIS, Remote Sensing, Thermal IR, Vegetation areas

Key words: afforestation, agriculture, mires, nutrients

The relationship between electrical conductivity (EC) of press-water extract and water content (WC) of peat growth medium at desorption was studied. A simple time-domain reflectometer (TDR), traditional laboratory conductivity meter and gravimetric weighing were used to measure EC and WC. The relationship between EC values measured with a laboratory conductivity meter from press-water extract and those measured with TDR directly from peat medium was curvilinear. The relationship between WC of peat measured with TDR and that determined gravimetrically, although nearly linear, was slightly sigmoidal. Empirical curve between EC values and WC values measured with TDR was close to the theoretical curve, which was calculated on the basis of increase in ion concentration at desorption. Transformed EC values of press-water extract were higher than the theoretically calculated values. For comparison of EC values measured from press-water extracts in various water contents, transforming coefficients were derived.

Key words: nutrient monitoring, fertilization, TDR

The rate of renewal of forests on drained peatlands in Finland will undergo a rapid rise in the near future as a large amount of these forests is approaching their renewal age. Indeed, forest renewal increasingly calls for familiarity with the special characteristics of peatland habitats. These special characteristics making them different from upland sites are primarily connected to hydrology, temperature conditions, nutrient status, and to changes in the composition of the ground vegetation. This literature review is focused on the effects of these site factors on the germination of tree seeds and the initial development of seedlings on different seedbeds.

Key words: drainage areas, natural regeneration, peatlands

The profitability of wood ash-fertilizing (5-16 t ha^-1) of four drained peatland Scots pine stands in central Finland was investigated. The profitability of forest drainage alone and forest drainage plus ash-fertilization was compared. After 44-56 years, the wood ash-fertilization had increased mean productivity by 3.1-12.1 m³ ha^-1 a^-1. Using an interest rate of 3 % and without subsidies, the net present value of the stands was 2500-20300 FIM ha^-1 higher as a result of the ash-fertilization than the value given by forest drainage alone. The real internal rate of return due to ash-fertilization without subsidies was 3.7-9.3 %. The interest rate, the fertilization dose and related costs, and the stumpage prices affected profitability. The state forest improvement subsidies further increased the profitablity of ash-fertilization.

Key words: forest fertilization, internal rate of return, net present value, Scots pine, stem volume, wood ash

The article presents the results of Finnish-Karelian co-operation in mire conservation research with the aim to study the diversity of mires in Finland and Russian Karelia on a uniform basis. The classification of mires in Finnish and Karelian schools of vegetation science has been compared. The vegetation of Lishkmokh mire has been studied using aerial photographs and field surveys. The area consists of ombrotrophic bog complexes as well as aapamires, all in a totally virgin state. As a result of the surveys, two maps of vegetation have been compiled. Results of vegetation analyses in releves have been presented in the form of tables and DCA ordination. According to the Finnish mire classification, 32 mire site types have been distinguished, which is a high number in an area of c. 2000 ha. On the basis of the high diversity of site types, and the occurrence of some rare plant species, e.g. Juncus stygius, Drepanocladus vernicosus and Meesia triquetra as well as some eastern species like Rubus humulifolius and Polygonum bistorta, the conservation value of Lishkmokh mire can be considered as very high.

Key words: Karelia, mire classification, mire conservation, mire vegetation

Slow-release phosphorus fertilizers have long been considered as a primary fertilization option on drained peatland forests in Finland. There has also been growing interest in using slow-release P-fertilizers as a better alternative to water-soluble fertilizers on agricultural land. Manufacture of different P-fertilizers, and those fertilizer and site properties which affect the rate of P release, are reviewed. The effects of slow-release P-fertilizers on plant growth and the liability to be leached into waterways are also discussed. In particular, the behaviour of slow-release P-fertilizers on drained peatland forests is considered.

Key words: fertilizer dissolution, fertilizer leaching, phosphate minerals, peatland forestry

The effects of fertilization and refertilization on the growth of pubescent birch (Betula pubescens) stands growing on drained peatlands in northern Finland were studied in eight field experiments. The treatments were: (i) control with no fertilization, (ii) fertilization with nitrogen (N), (iii) fertilization with phosphorus and potassium (PK), and (iv) fertilization with nitrogen, phosphorus, and potassium (NPK). The sites represented four different mesotrophic to eutrophic site types with stand median heights ranging from 7 m to 13 m. Tree growth was monitored at stand level during periods of five to eleven years following the setting up of the experiments and during periods of 4 to 7 years following the repetition of the treatments in 1985. At the end of the second period, sun-exposed leaves were sampled from two stands in August 1990 for the purpose of conducting foliar nutrient analyses. The first-time fertilization treatments did not affect tree growth on any of the site types. Following the repetition of the treatments, the stands responded positively to NPK or PK fertilization on all site types except on the shallow-peated herb-rich peatland forest. There was no response to mere N-fertilization on any of the site types. The growth responses observed were weaker than those reported for Scots pine in similar climatic conditions.

Key words: Betula pubescens, foliar nutrients, growth responses, nitrogen, peatland, phosphorus, potassium