Comparison of photosynthetic traits of codominant subalpine conifers Abies veitchii and A. mariesii in central Japan

摘要

AbstractEvergreen conifersAbies mariesiiandA. veitchiicodominate in the subalpine zone in central Japan. This study compared the photosynthetic light response curves and related leaf traits of 1-year-old needles between the two species to examine whether photosynthetic traits ofA. veitchiiare more favorable for growth in bright conditions than those ofA. mariesii. Saplings of the two species were sampled at forest edge (FE) and forest understory (FU). FE saplings of the two species showed more shade-intolerant traits (i.e., lower initial slope of photosynthesis light response curve, greater light compensation point and dark respiration rate) than FU saplings. Maximum photosynthetic rate and leaf nitrogen concentration were greater inA. veitchiithanA. mariesiifor both FE and FU saplings. Photosynthetic nitrogen use efficiency (PNUE) was also greater inA. veitchiithanA. mariesii. On the contrary, leaf mass per area was greater inA. mariesiithanA. veitchiifor both FE and FU saplings. Therefore, this study showed that photosynthetic traits ofA. veitchiiare more favorable for growth in bright conditions compared withA. mariesii, andA. mariesiihas more robust needles at the expense of PNUE.