Due to warm springs and summers, acorns have been falling almost three weeks earlier than fifty years ago since this century, according to thousands of observations on Sunday. Nature Today has investigated.
Fruit ripening observations since 1902 show that the fruits of wild rowan, common elderberry, pedunculate oak and white horse chestnut now fall earlier. Fifty years ago, most summer oak acorns did not fall until the second half of September. This year the peak is expected around the end of August or the beginning of September.
The fruits fall earlier mainly due to the very high temperatures that ensure early fruit ripening. Due to the rising temperatures in the Netherlands, trees now bloom earlier, which means that this process starts earlier. The development of the fruits is also faster due to the higher temperatures.
The Netherlands is dealing with a warm spring and a warm summer this year. The average temperature this year from 1 January to 20 August is in third place of the warmest years since the measurements started in 1901. Only in 2007 and 2014 was it even warmer.
Yet it is not a record how early the fruit ripening will take place this year. Due to the relatively normal temperatures in May and the cool temperatures in July, this takes place for all types of acorns at the average time of the past twenty years.
The consequences of early fruit ripening are still unclear
It is not yet clear what the consequences are of early fruit ripening. Animal species may be more likely to collect them to build reserves for the winter, which will also cause the acorns to run out sooner.
In addition to acorns, leaves fall from the trees earlier this year. This is caused by dryness and heat. As a result, trees evaporate more moisture than they can absorb. To keep them from drying out, the trees may drop leaves.
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