Articles containing the keyword 'humidity'

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 investigation is divided into statistical and experimental sections, the latter of which were conducted in a Vaccinium type Scots pine (Pinus sylvestris L.) stand with the aim of elucidating the interdependence of soil humidity and meteorological factors. The moisture content of pine needles and moss and wooden cylinders placed on the soil or slightly over the ground was determined by weighing. The results showed that there is correlation between the moisture content of the wooden cylinders and the relative humidity of air during the days without rain. Correlation between moisture content of pine needles and moss with the air was slightly poorer.

In the statistical section, based on meteorological observations made in the geophysical observatory at Sodankylä in Northern Finland in 1920-1943, and forest fire statistics of the area, forest fire days and days without forest fires were divided into 40 temperature-humidity groups. Of the 391 forest fires observed in the area, the cause of the fire was known in 353 cases, and 69% of these were caused by lightning. A forest fire danger index was calculated using the data. A sharp increase in the burned area when the index exceeded the limit k=0.3 seem to be explained by thunderstorms, which are the most notable cause of forest fires in the Sodankylä area.

The forest fire index was calculated also at four meteorological stations in different parts of the country using weather observations in 1927-1936. It appears that the number of days in which the k>0.1 decreases when proceeding northwards, obviously because of the shortening of the summer. On the other hand, the number of days in which k>0.3 increases towards the north.

The PDF includes a summary in English.

• Franssila, E-mail: mf@mm.unknown

• Tullus, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: arvo.tullus@ut.ee
• Sellin, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: arne.sellin@ut.ee
• Kupper, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: priit.kupper@ut.ee
• Lutter, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: reimo.lutter@emu.ee
• Pärn, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: linnar.parn@emu.ee
• Jasinska, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia & Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland E-mail: jasiak9@wp.pl
• Alber, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: meeli.alber@ut.ee
• Kukk, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: maarja.kukk@ut.ee
• Tullus, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: tea.tullus@emu.ee
• Tullus, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: hardi.tullus@emu.ee
• Lõhmus, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: krista.lohmus@ut.ee
• Sõber, Department of Botany, Institute of Ecology and Earth Sciences, Faculty of Science and Technology, University of Tartu, Lai 40, Tartu 51005, Estonia E-mail: anu.sober@ut.ee