ALPECOLE
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Plants and climatic stress

Early freezing events in late summer and autumn

 

Here an example: During the night of 27/28 August 1995, a cold northwesterly front crossed the central Swiss Alps, with a heavy snow fall, followed by clear weather. Minimum 2 m air temperature during the first night dropped to -4.1 °C, followed by -5.4 °C 2 days later (much of the snow had melted by that time) and -4.3 °C after all snow had disappeared (see below). Ground temperatures possibly dropped 2-3 K lower due to radiative cooling. Near the summit of the Furka Pass road at 2500 m altitude (300 m above treeline), late flowering species lost their entire diaspore crop, a large number of species lost a substantial fraction of their fully active leaves.

1 - Temperature A killed sensitive organs taller than 10 cm, temperature B killed any sensitive organs above ground.

 

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29 August 2011
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