MetINFO - Daily growth of trees

^↑ Go up

Tammela Norway spruce	Hyytiälä Norway spruce	Punkaharju Norway spruce	Punkaharju silver birch	Kivalo Norway spruce

Change of stem diameter during the growing season, mm

Weekly growth →

^↑ Go up

Tammela Norway spruce	Hyytiälä Norway spruce	Punkaharju Norway spruce	Punkaharju silver birch	Kivalo Norway spruce

Change of stem diameter during the growing season, mm

Weekly growth →

^↑ Go up

Tammela Norway spruce	Hyytiälä Norway spruce	Punkaharju Norway spruce	Punkaharju silver birch	Kivalo Norway spruce

Change of stem diameter during the growing season, mm

Weekly growth →

^↑ Go up

Tammela Norway spruce	Hyytiälä Norway spruce	Punkaharju Norway spruce	Punkaharju silver birch	Kivalo Norway spruce

Change of stem diameter during the growing season, mm

Weekly growth →

^↑ Go up

September 04. 2012

From the beginning of June to the half of July the diameter growth of trees was intensive because of favourable warm and humid weather conditions in Finland. After that it was slower and ceased at the end of July with spruce, but continued a week longer with birch. The growth 2012 in Finland was almost as high as in 2011. In southern Finland, diameter increment of Norway spruce has started approximately on May 22.-23. The date is about a week later than in the two previous years. Instead, diameter increment of silver birch in Punkaharju (south-eastern Finland) started in mid May, at the same time as in the previous year.The beginning of this summer was cool and that's why the accumulation of growth was at first slower than in the previuos year. In Kivalo (northern Finland), diameter increment has started on June 6.

In spring 2012, daily mean temperature has followed the means of years 1981-2010. So, the onset of the diameter increment is also in accordance with the average timing. In the previous springs, 2010 and 2011, the early onset of diameter increment was due to warm period occurring before the mid May, when temperatures rose above +25 °C. In this spring, a warm period took place on May 17.-25. but the temperature has only occasionally exceeded the heat limit of +25 °C. South-eastern Finland has been warmer than the rest of Finland, which can explain the early onset and high level of diameter increment in silver birch in Punkaharju. The growth of spruce there has been similar to the growth on the previous year.

The changes in stem diameter recorded by a dendrometer band are not solely due to the formation of new cells. The stems also swell and shrink due to changes in their water potential. In a dry, rainless day, trees may transpire more water than the root system is able to obtain from the soil. In a rainy day after a dry period, stem diameter then suddenly increases with increasing water content of the stem, but may decrease again with decreasing water content. The reversible changes in the stem diameter of Norway spruce can be up to 0.5 mm. In silver birch, the reversible changes are smaller than those in conifers. In spring 2012, such rainy periods were on May 5.-6., 10.-11. and 16.-17. During the growth period this swell took place on June 2.-3., 17.-20. and 24.-26. Alternating rainy and dry periods from the half of July have caused again variation in the diameters.

Stem diameter has also diurnal variations. Due to high transpiration, stems slightly shrink during a day. In the night, stems swell again with decreasing transpiration. The diurnal reversible variations are also higher in Norway spruce than in silver birch.