Trees rehydrate and grow mostly at night, when soil and air are more humid.
PHOTO: ARTERRA PICTURE LIBRARY/ALAMY STOCK PHOTO
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Trees rehydrate and grow mostly at night, when soil and air are more humid.
PHOTO: ARTERRA PICTURE LIBRARY/ALAMY STOCK PHOTO
Tree rings provide an annual report on how trees grow. Using continuous dendrometer measurements, Zweifel et al. were able to measure radial growth in tree trunks moment by moment. Deciduous or evergreen trees were surveyed in a selection of Swiss forests that had been mostly managed sustainably since 1876. The trees mainly grew at night, most rapidly just before dawn. Midday to afternoon was evidently the down time for radial growth. Growth in girth was aided by soil moisture and air humidity; indeed, trees needed several hours of night to slake the thirst they acquired during the day. The authors suggest that radial stem growth depends on nocturnal atmospheric conditions, whereas carbon assimilation depends more on daytime conditions.
New Phytol. 10.1111/nph.17552 (2021).