Current issue: 56(2)
Under compilation: 56(3)
Application of growth regulators, primarily gibberellins, has become an efficient method of flowering regulation in many coniferous forest trees. In this paper some results are discussed with respect to various genetic processes in seed orchards. It is concluded that there are still several unsolved problems in the regulation of flowering in forest seed orchards. These problems are related to different genetic processes occurring in the seed orchards and they should be taken into account in endeavouring to produce genetically improved seeds.
Visible frost damage to forest trees in Sweden seldom occurs in winter but is frequent in late spring, summer and early autumn. Frosts are frequent in all seasons in various parts of Sweden, even in the southernmost part (lat. 56°, N) and temperatures may be as low as -10°C even around mid-summer. Ice crystal formation within the tissues, which in most seedlings takes place at around -2°C, causes injury, not the sub-zero temperatures themselves.
The apical meristem, the elongated zone, and the needles of seedlings of Picea abies (L.) H. Karst. in a growing phase were damaged at about -3°C and those of Pinus sylvestris L. at about -6°C. Other species of the genus Pinus were tested and most were found to be damaged at about -6°C, with some variations. Picea species tested were damaged at about -3°C to -4°C.
A method has been designed to compare the response of different species to winter desiccation, which occurs under conditions of (1) low night temperature, (2) very high irradiation and increase in needle temperature during the photoperiod, (3) frozen soil, and (4) low wind speed. There were differences in response to winter desiccation between pine and spruce species. Seedlings of Pinus contorta tolerated these winter desiccation conditions much better than those of P. sylvestris or Picea abies. Picea mariana was the least tolerant of the species tested.
The PDF includes an abstract in Finnish.
The fungal symbiont of ectendomycorrhizae is an ascomycete Wilcoxina (Tricharina) mikolae Yang & Korf. It forms ectendomycorrhizae with Pinus and Larix and ectomycorrhizae with Abies, Picea, Pseudotsuga and Tsuga. It is common in forest nurseries around the world. After transplanting the seedlings into natural forest soil, indegenous fungi rapidly replace Wilcoxina. Inoculation of nursery soil with Wilcoxina is recommended if soil has been sterilized or for other reasons mycorrhizal fungi are absent.
The PDF includes a summary in Finnish.
A monitoring program is planned for the terrestrial environment around industries in Sweden, which emit acid compounds and heavy metals. Directions for the County Government Boards are being prepared. The paper deals with the present pollution situation in Sweden, based on recent scientific results, the justifications for local monitoring, and the organizing of the monitoring including the parameters suggested.
Four examples from a case study at an oil power station illustrate reporting of the data and the difficulties in interpreting the results. The examples are the distribution of a lichen indicator, heavy metal content and phosphatase activity in the moor layer, soil respiration and tree growth.
The aim of the present study was to collect information presented in literature concerning the development and germination of the seeds of coniferous trees with special reference to those species which thrive in the conditions prevailing in Finland. Along with the increase in the importance of direct seeding as a silvicultural means in Northern Finland, there is a growing demand for methods by means of which the germination of seeds could be promoted. According to the results obtained from previous studies, such a method can be found, provided that a practically usable and reliable pre-germination method is developed.
The PDF includes a summary in English.
The effective heating values of the above and below ground biomass components of mature Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), downy birch (Betula pubescens Ehrh), silver birch (B. pendula Roth), grey alder (Alnus incana (L.) Moench), black alder (A. glutinosa (L.) Gaertn.) and aspen (Populus tremula L.) were studied. Each sample tree was divided into wood, bark and foliage components. Bomb calorimetry was used to determine the calorimetric heating values.
The species is a significant factor in the heating value of individual tree components. The heating value of the wood proper is highest in conifers. Broadleaved species have a higher heating value of bark than conifers. The species factor diminishes when the weighted heating value of crown, whole stems or stump-root-system are considered. The crown material has a higher heating value per unit weight in comparison with fuelwood from small-sized stems or whole trees. The additional advantages of coniferous crown material are that it is non-industrial biomass resource and is readily available. The variability of both the chemical composition and the heating value is small in any given tree component of any species. However, lignin, carbohydrate and extractive content were found to vary from one part of the tree to another and to correlate with the heating value
Polymorphisms at a set of eighteen nuclear (nSSR) and chloroplast (cpSSR) microsatellite loci were investigated in sixteen populations of Scots pine (Pinus sylvestris L.) derived from the provenance trial experiment and representative of the species distribution range and climatic zones in Poland. The patterns of genetic variation were compared to the reference samples from the species distribution in Europe and Asia. A similar level of genetic variation and no evidence of population structure was found among the Polish stands. They showed genetic similarity and homogenous patterns of allelic frequency spectra compared to the Northern European populations. Those populations were genetically divergent compared to the marginal populations from Turkey, Spain and Scotland. The population structure patterns reflect the phylogeography of the species and the divergence of populations that most likely do not share recent history. As the analysed provenance trial populations from Poland are diverged in phenotypic traits but are genetically similar, they could be used to test for selection at genomic regions that influence variation in quantitative traits.
At sites with either peat or mineral soils in large areas of boreal forests, high soil-water contents hamper tree growth and drainage can significantly increase growth. Hence, areas covering about 15 × 106 ha of northern peatlands and wet mineral soils have been drained for forestry purposes. Usually ditches gradually deteriorate, thus reducing their functionality as drains, and ditch-network maintenance (DNM) might be needed to maintain stand growth rates enabled by the original ditching. This article reviews current knowledge on establishing the need for DNM in boreal forest stands, subsequent growth responses, and the financial outcome of the activity. The issues covered in the review are: (i) ditching, changes in ditches over time and the need for DNM; (ii) interactions between soil water and both stand properties and stand management; (iii) ground-water level (GWL) and tree growth responses to DNM; and (iv) financial viability of DNM. Conclusions about the current understanding of issues related to DNM are drawn and implications for DNM in practice are summarized. Finally, gaps in knowledge are identified and research needs are suggested.