Three different growth responses of six gymnosperm species under
long-term excessive irrigation and traits determining species resistance
In the era of extreme weather events, plant resistance to excessive
water should be considered for plantations in frequently flooded areas.
Therefore, we quantified the resistance to excessive irrigation (REI) in
seedlings of six conifer species on the basis of their morphological,
physiological, and biochemical traits. Two different irrigation regimes,
natural precipitation as a control treatment and additional irrigation
by sprinklers (30.89 ± 2.80 % above natural precipitation) as excessive
irrigation, were applied for three consecutive years. There were three
distinct responses in biomass accumulation: Chamaecyparis obtusa and
Abies holophylla significantly increased their aboveground and
underground biomass and showed a strong REI; Pinus thunbergii and P.
densiflora, both resistant to drought, significantly decreased their
aboveground and underground biomass and showed a weak REI. Larix
kaempferi and Pinus koraiensis showed a medium REI with only aboveground
biomass increment in the former and no biomass change in the latter.
Plant biomass responses corresponded well with the changes in
morphological, physiological, and biochemical traits. Biomass
augmentation resulted from an increase in leaf size, leaf mass per area
(LMA), maximum photosynthesis rate, and leaf water potential.
Flavonoids, LMA, and stomatal conductance are the most important traits
to access species REI.