Timing of Drought Affected the Growth, Physiology, and Mortality of Mongolian Pine Saplings
Qian, Hui; Dong, Ai-Mei; Roitto, Marja; Xiang, Di-Ying; Zhang, Gang; Repo, Tapani; Wang, Ai-Fang (2021)
Qian, Hui
Dong, Ai-Mei
Roitto, Marja
Xiang, Di-Ying
Zhang, Gang
Repo, Tapani
Wang, Ai-Fang
Julkaisusarja
Forests
Volyymi
12
Sivut
16 p.
Multidisciplinary Digital Publishing Institute (MDPI)
2021
Julkaisun pysyvä osoite on
http://urn.fi/URN:NBN:fi-fe2021110153134
http://urn.fi/URN:NBN:fi-fe2021110153134
Tiivistelmä
Background and Objectives: More frequent and severe droughts are occurring due to
climate change in northern China. In addition to intensity and duration, the timing of droughts may
be decisive for its impacts on tree growth, mortality, and the whole forest ecosystem. The aim of this
study was to compare the effect of drought occurring in the early- and mid-growing season on the
growth and physiology of Mongolian pine (Pinus sylvestris var. mongolica Litv.) saplings. Materials
and Methods: Four-year-old container saplings that were about to sprout were exposed to three
treatments: (i) regular irrigation throughout the growing season (CTRL), (ii) no irrigation in the
early growing season (weeks 1–5) followed by regular irrigation (EGD), (iii) no irrigation in the mid
growing season (weeks 5–10), and regular irrigation in the early and late growing season (MGD). We
measured the root and shoot growth, sapling mortality, and the physiological changes in the roots
and needles periodically. Results: Drought in the mid growing season was more harmful than in
the early growing season in terms of chlorophyll fluorescence, electrolyte leakage of needles, needle
length, stem diameter increment, and sapling mortality. The high mortality in the mid growing
season might be attributed to the joint effect of drought and high temperature. Drought in the early
growing season decreased root growth, and the starch and soluble sugars in roots as much as the
drought in the mid growing season. Abscisic acid concentration increased in fine roots, but decreased
in old needles after drought. Conclusions: Special attention should be paid on forest sites susceptible
to drought during afforestation in the face of ongoing climate change.
climate change in northern China. In addition to intensity and duration, the timing of droughts may
be decisive for its impacts on tree growth, mortality, and the whole forest ecosystem. The aim of this
study was to compare the effect of drought occurring in the early- and mid-growing season on the
growth and physiology of Mongolian pine (Pinus sylvestris var. mongolica Litv.) saplings. Materials
and Methods: Four-year-old container saplings that were about to sprout were exposed to three
treatments: (i) regular irrigation throughout the growing season (CTRL), (ii) no irrigation in the
early growing season (weeks 1–5) followed by regular irrigation (EGD), (iii) no irrigation in the mid
growing season (weeks 5–10), and regular irrigation in the early and late growing season (MGD). We
measured the root and shoot growth, sapling mortality, and the physiological changes in the roots
and needles periodically. Results: Drought in the mid growing season was more harmful than in
the early growing season in terms of chlorophyll fluorescence, electrolyte leakage of needles, needle
length, stem diameter increment, and sapling mortality. The high mortality in the mid growing
season might be attributed to the joint effect of drought and high temperature. Drought in the early
growing season decreased root growth, and the starch and soluble sugars in roots as much as the
drought in the mid growing season. Abscisic acid concentration increased in fine roots, but decreased
in old needles after drought. Conclusions: Special attention should be paid on forest sites susceptible
to drought during afforestation in the face of ongoing climate change.
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