Tuesday, August 13, 2019: 2:10 PM
M112, Kentucky International Convention Center
Siyeon Byeon1, Wookyung Song2, Minjee Park2, Sukyung Kim1, HoonTaek Lee2, Jihyeon Jeon1, Minsu Lee1, Hyemin Lim3 and Hyun Seok Kim1,4,5,6,7, (1)Department of Forest Sciences, Seoul National University, Seoul, Korea, Republic of (South), (2)National Institute for Forest Sciences, Seoul, Korea, Republic of (South), (3)Forest Genetic Resource Department, National Institute for Forest Sciences, Suwon, Korea, Republic of (South), (4)Interdisciplinary Program in Agricultural and Forest Meteorology, Seoul National University, Seoul, Korea, Republic of (South), (5)Department of Forest Sciences, Institute of Future Environmental and Forest Resources, Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea, Republic of (South), (6)National Center for AgroMeteorology, Seoul National University, Seoul, Korea, Republic of (South), (7)Research Institute of Agriculture and Life Sciences, Seoul National University, Korea, Republic of (South)
Background/Question/Methods: Elevated CO
2 concentration could enhanced forest productivity, which is substantially affected by soil nitrogen availability and its efficiency. In addition, the change of leaf nitrogen allocation under long term elevated CO
2 [eCO
2] exposure is important to predict future prediction. This study was investigated the changes of photosynthetic characteristics and leaf nitrogen allocation of Japanese red pine (
Pinus densiflora), Korean ash (
Fraxinus rhynchophylla) and Korean whitebeam (
Sorbus alnifolia), grown under three different CO
2 concentrations (ambient [aCO
2], ambient x 1.4 [eCO
21.4] and ambient x 1.8 [eCO
21.8]) for nine years.
Results/Conclusions: Morphological characteristics such as leaf size and leaf mass per area tended to be higher at eCO2 than aCO2 (maximum p < 0.001). In case of photosynthetic characteristics, maximum photosynthetic rate (Amax) was higher at eCO2 than aCO2, especially in Korean ash (maximum p = 0.009). On the other hand, the maximum carboxylation rate (VCmax) and maximum electron transfer rate (Jmax), decreased significantly at eCO21.8 (maximum p = 0.002). Photosynthetic down-regulation of these species was not caused by decrease of total leaf nitrogen per unit area [Narea], it was rather caused by the changes in N allocation. The N allocation to Rubisco [NRub] decreased with CO2 enrichment (p = 0.02), while nitrogen to chlorophyll [Nchl] increased 14.0% at eCO2 than aCO2 (p < 0.001) and cell wall [Ncw] did not change among treatments (p = 0.823), In addition, the changes of N allocation were species- and position-specific. Reduction of NRub and enhancement of Nchl were the most pronounced in Korean whitebeam, but they were not significant in Japanese red pine. Ncw decreased significantly only in Korean ash. Reduction of NRub in eCO2 was greater in upper canopy than in lower canopy, while the enhancement of NFchl was not different among canopy positions. The photosynthetic nitrogen use efficiency [PNUE] enhanced due to the increment of Nchl and increased the amount of photosynthesis and maintained biomass production despite of photosynthetic capacity reduction. Our result implied the effect of elevated CO2 could last longer even with the N limitation due to the enhancement of PNUE caused by change of N allocation.
