Species-Specific Nitrogen Resorption Efficiency in Quercus mongolica and Acer mono in Response to Elevated CO2 and Soil N Deficiency

To test the effects of elevated CO2 and soil N deficiency on resorption efficiency (NRE) from senescing leaves in two non-N2-fixing deciduous broadleaved tree species, Japanese oak (Quercus mongolica var. grosseserrata Blume) Painted maple (Acer mono Maxim. glabrum (Lév. Et Van’t.) Hara), potted seedlings were grown a natural daylight phytotron with either ambient or conditions (36 Pa 72 CO2) levels (52.5 5.25 mg pot−1 week−1 for high low N, respectively). We examined content (Nmass) mature senescent leaves, as well photosynthesis growth plants, calculated both mass-based NRE (NREmass) leaf area-based (NREarea). In Nmass decreased whereas mass per area (LMA) increased under CO2, regardless treatments. Q. mongolica, maximum rate carboxylation (Vcmax) electron transport (Jmax) reduced by but Vcmax exhibited an interactive effect However, A. mono, Jmax The partitioning photosynthetic function within was also significantly species mono. senesced increase (Q. mongolica) no (A. mono) CO2. NREarea affected treatments, decrease compared to N. treatments CO2; however, unlike case it speculate that these interspecific differences responses allocation, indicated (Vcmax Jmax) morphological may have during defoliation N-deficient conditions.