Wood anatomy and tree-ring stable isotopes indicate a recent decline in water-use efficiency in the desert tree Moringa peregrina

• Published in: International journal of biometeorology Vol. 66; no. 1; pp. 127 - 137
• Main Authors: Farahat, Emad, Cherubini, Paolo, Saurer, Matthias, Gärtner, Holger
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2022; Springer Nature B.V
• Subjects: Anatomy; Animal Physiology; Bark; Biological and Medical Physics; Biophysics; Carbon content; Carbon Isotopes; Climate change; Desert plants; Drought; Drought conditions; Earth and Environmental Science; Efficiency; Environment; Environmental Health; Future climates; Isotopes; Meteorology; Moringa; Moringa peregrina; Original Paper; Plant Physiology; Stable isotopes; Standard error; Tree rings; Trees; Water; Water conservation; Water use; Wood; Wood anatomy; Drought stress; Isotopes; Water-use efficiency; Moringa peregrina
• ISSN: 0020-7128; 1432-1254
• DOI: 10.1007/s00484-021-02198-7

The ability of desert plants to adapt to future climate changes and maximize their water-use efficiency will determine their survival. This study uses wood anatomy and δ
13
C and δ
18
O isotope analyses to investigate how
Moringa peregrina
trees in the Egyptian desert have responded to the environment over the last 10 years. Our results show that
M. peregrina
tree-ring widths (TRWs) have generally declined over the last decade, although individual series are characterized by high variability and low Rbars. Vessel lumen area percentages (VLA%) are low in wet years but increase significantly in dry years, such as the period 2017–2020. Stable δ
13
C isotope values decrease between 2010 (− 23.4‰) and 2020 (− 24.9‰), reflecting an unexpected response to an increase in drought conditions. The mean δ
18
O value (± standard error, SE) for the first ten rings of each tree from bark to pith (2020–2010) is 33.0 ‰ ± 0.85 with a range of 29.2–36.3‰, which indicates a common drought signal. The intrinsic water-use efficiency (iWUE) declines gradually with time, from 130.0 µmol mol
−1
in 2010 to 119.4 µmol mol
−1
in 2020. The intercellular carbon concentration (C
i
) and C
i
/C
a
ratio increase over the same period, likely as a result of decreasing iWUE. The results show that
M. peregrina
trees seem to cool their leaves and the boundary air at the cost of saving water.