Background/Question/Methods: In the era of climate change and population explosion, the importance of natural forests and their conservation are increasing. However, frequency and severity of drought are expected to increase, therefore the plantation forests managed by human should achieve maximum efficiency for their production. As a first step, drought tolerance of tree species should be considered for the maximum survival in the field. In this study, we examined the morphological, hydraulic and anatomical traits of five popular plantation seedlings: Sargent cherry (
Prunus sargentii), Sawtooth oak (
Quercus acutissima), East Asian ash (
Fraxinus rhynchophylla) and Japanese larch (
Larix kaempferi), and Korean red pine (
Pinus densiflora) under three different irrigation regimes: control (CT; 100% precipitation (
P)), light drought (LD; 40% reduction of
P), and heavy drought (HD; 80% reduction of
P). The objectives of this study were to determine the morphological and physiological responses and compare anatomical structures to assess their possible role for maintain plant-water relations. We analyzed the leaf size, leaf mass per area (LMA, g cm
-2), and vegetative growth as morphological characteristics, in addition to photosynthetic parameters (
Amax and
Gs), leaf water potential, transpiration rate (using external heat ratio method), carbon isotopic compositions, and leaf and stem anatomical traits.
Results/Conclusions: All the examined species significantly decreased their leaf sizes, however, East Asian ash, Sawtooth oak, and Sargent cherry reduced their leaf width but Japanese larch and Korean red pine reduced their leaf length. On the other hand, LMA was significantly increased in most species except East Asian ash and Korean red pine. Maximum photosynthesis rate (Amax), and stomatal conductance (Gs) at Amax were reduced in all species expect Japanese larch and Korean red pine. Transpiration rate was significantly reduced in Sargent cherry and Sawtooth oak but not in Japanese larch, Korean red pine and East Asian ash. Drought stress significantly reduced the predawn (ΨPD) and midday leaf water potential (ΨMD) in East Asian ash, Sawtooth oak, and Sargent cherry but not in Japanese larch and Korean red pine. Generally, broadleaved species showed more aniso-hydric behaviors, while conifers showed more iso-hydric behaviors. Anatomically, the xylem vessels feature (density, area, and diameter) and leaf thickness were reduced but the stomatal density (Sd) mostly increased in broad leaf species. Our results provide the valuable insights for morphological, physiological, hydraulic and anatomical traits and suggest conifer species had greater resistance and resilience than the broadleaved species.
