Silva Fennica vol. 17 no. 1 | 1983
Category : Article
Climatological factors determining the natural northern boundary in Europe of oak (Quercus robur L.) were investigated. The natural northern boundary of oak corresponds in detail to the curve at which the growing season, beginning at +5°C in spring and ending at +10°C in autumn, is of a certain constant length. The northern boundaries for more oceanic plants can be explained by prolonged autumn activity. This is obviously the general explanation or the concept of oceanity. Oak spread markedly in Finland in the summers during 1961–1975, which on an average were as warm but much dried than those during 1931–1960. The importance of humidity for oak was discussed.
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Solantie,
E-mail:
rs@mm.unknown
The resistance of Finnish softwood timbers to Macrotermitinae termites was tentatively tested under tropical conditions in Zambia using a field microtest method. Picea abies (L.) H. Karst. and Larix sibirica L. sapwood and heartwood, as well as Pinus sylvestris L. sapwood, and the sapwood of the locally grown Pinus kesiya, exhibited no natural termite resistance. On the other hand, Juniperus communis heartwood appeared to be virtually immune and the heartwood of P. Sylvestris had some resistance. There were also some differences in the resistance of the heartwood of the different P. Sylvestris individuals tested, which was correlated with the width of the annual rings in the wood samples. The termite species involved were Microtermes sp. and Odontotermes sp. The possibilities of using different types of Finnish softwood timber in the regions in the tropics where there is a risk of termite damage is discussed.
The PDF includes a summary in Finnish.
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Löyttyniemi,
E-mail:
kl@mm.unknown
The choice of sampling method is of prime importance when seeking relevant information about the height distribution and spatial arrangement of seedlings in the regeneration surveys. It is suggested that the size of sampling plots should depend on the height of the seedlings. Tall seedlings should be sampled from a larger area than short ones since tall seedlings are more important for the future development of the stand. We suggest principles for a technical development task to construct a device which is easy to use in practical regeneration surveys and by which sampling can be made proportional to plant height or any desired function of height.
The PDF includes a summary in Finnish.
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Lappi,
E-mail:
jl@mm.unknown
- Kotisaari, E-mail: ak@mm.unknown
- Smolander, E-mail: hs@mm.unknown
The role played by the medium and fine silt and clay contents in determining the quartiles and the degree of stratification from a cumulative particle-size curve was studied in order to determine what time savings could be made in the sedimentation phase of soil mechanical analysis. The clay content of the samples was, in general, found to be so small that it did not affect the parameters studied. In contrast to this, the medium and fine silt content affected the lower quartile of the distribution for many soils classified as finer than medium sand. Consequently, only the omission of the determination of the clay fraction can be recommended as a time-saving measure in mechanical analysis.
The PDF includes a summary in Finnish.
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Lipas,
E-mail:
el@mm.unknown
The growth response of aspen (Populus tremula L.) to fertilization was studied in an experiment laid out in a naturally regenerated 35-year old stand on a previously burned-over land. The site was rather fertile. One-tree plot method was used. Applications of nitrogen (150 kg/ha as ammonium nitrate with lime), phosphorus (35 kg/ha as superphosphate), and potassium (66 kg/ha as potassium chloride) separately and in all possible combinations were used; the test included 11 replications. The growth reaction was measured as basal area growth excluding bark during 5 years. The factorial effects were computed using Yates method.
Potassium did not have any effect on basal growth of the trees. The response to phosphorus was also rather small. On the other hand, nitrogen appeared to have increased the basal area growth. The growth increase obtained with nitrogen alone was greater than when it was applied together with phosphorus and/or potassium.
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Heinonen,
E-mail:
th@mm.unknown
Altitude fluctuation of mire surface proportional to that of the groundwater table is presented for three virgin pine mires in Eastern Finland during the growing season 1982. The average amplitude of the surface fluctuation was found to be dependent on the period representing a certain type of weather, being limited to a certain maximum. The average amplitude of the surface fluctuation ranged from 18 to 45 mm; each of the mires followed a fluctuation scale of its own.
The daily fluctuation rates were low, generally 0.5–1 mm. No sudden fluctuation peaks occurred. Regularities in the surface fluctuation were caused by the duration of the period representing continuous sinking or rise of the groundwater table, and magnitude of it. The daily rate of the surface fluctuation related to that of the groundwater table was smaller in the beginning of such period than at the end of the same period. The one-directional rise or sinking of the altitude of the mire surface according to the groundwater table fluctuation is responsible for the autocorrelation of the long-term regression data.
The PDF includes a summary in Finnish.
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Kurimo,
E-mail:
hk@mm.unknown
The present study deals with the effect of forest drainage on some quality factors of brook waters. Under study were several brooks in the basin of the Kiiminkijoki River as well as its main tributary, the Nuorittajoki River. These are located in Northern Finland and belong to the international water program Project Aqua.
The following values were determined for the water samples: pH, electric conductivity, colour, concentration of suspended solids., NO2, NO3, and NH4 nitrogen concentrations, dissolved and total phosphorus, and Ca, Mg, K and Fe concentrations. Water quality in the brooks was monitored prior to and after ditching. A statistically significant change was noted in colour, in the concentration of suspended solids, in the NH4 concentration and in some brooks also in the pH value and in the total phosphorus, K, and Fe concentrations.
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Hynninen,
E-mail:
ph@mm.unknown
- Sepponen, E-mail: ps@mm.unknown
The needle area distribution and crown structure of a young planted Scots pine (Pinus sylvestris L.) stand are described. The crown structure and crown shape showed apparent regularity in crown structure regardless of stand dynamics. Similarly, the shoot structure and individual needle area showed regularity in the number of needles per branch and shoot length unit, and consequent phytoarea density inside the needle cylinder. Also, the shoot area and needle area distributions were found to show a regular distribution of needle biomass throughout the crown, also inside the crown, in the dominant trees. In the suppressed trees the needle biomass was located in the upper crown and on the surface area of the crown. Estimates of the canopy needle area and distributions are given. The results were applied in calculations of the within-stand light regime. The results correlated well with the empirical results.
The PDF includes a summary in Finnish.
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Kellomäki,
E-mail:
sk@mm.unknown
- Oker-Blom, E-mail: po@mm.unknown