Current issue: 54(2)
Under compilation: 54(3)
The significance of water budget in June and July for forest and peatland vegetation, and consequent effects on fauna, climate and agriculture has been studied.
In June, the difference between evaporation and precipitation is greater than it is later in the summer. North of the line zero difference of evaporation and precipitation, coinciding with a line of sharp change in forest vegetation, the uppermost part of podsol remains wet throughout the summer. During July, the line of zero difference moves from north to south over the greater part of Finland, run-off being minute and podsol at the driest in this month. This line, indicating the length of the period with evaporation greater than precipitation and causing a sharp change in forest vegetation, in frequency of peatlands, amount of growing stock productive capacity of forests etc. This line is significant also for cultivation: because of the lower evaporation north of this line, night temperature below the freezing point often appear in summer.
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Metsähallitus (Forest Service) decided to protect two areas around Hiisijärvi lake in Eastern Finland already in 1916. Later, a natural park was suggested to be established in the area. A survey of the vegetation in the area was composed in 1931-1932. The total land area of the protected area was 3.5 km3. A vegetation map was drawn based on a nature inventory. A detailed description of the forest site types, peatland types, aquatic flora and the vegetation of the area are included in the article. The calcareous soil promotes rich vegetation. Typical for the area are also rich fens. The area can be divided to a eutrophic and a oligotrophic part.
The PDF includes a summary in German.