Leaf phenotypic, photosynthetic traits and main activity compounds differences among four heteromorphic leaves of <i>Litsea coreana</i> Levl. var. <i>sinensis</i>

Abstract Litsea coreana Levl. var. sinensis has developed four heteromorphic leaf types to adapt to the local environment. This study investigated functional traits of four heteromorphic leaf types associated with leaf morphology, anatomy, photosynthesis, and activity compounds, to elucidate their niche differentiation within a single tree. Lanceolate (La) type had the largest leaf length (LL = 8.4 cm), leaf shape index (LSI = 2.8), leaf perimeter (LP = 18.5 cm), but low palisade tissue thickness (TPTT), light saturation point (LSP), and light compensation point (LCP), allowing them suited for varied positions and mild, humid climates. Ovoid (Ov) and orbiculate (Or) types had highest leaf thickness (LT = 0.2 mm) and high TPTT (66.9 and 63.9 μm), high chlorophyll (0.695 and 0.696 mg g−1), high net photosynthetic rate (PNmax = 8.1 and 6.6 μmol m−2 s−1), high total flavonoid content (TFC = 45.2 and 47.7 mg g−1), indicating their adaptation to top and edge canopy positions with high temperatures and light conditions. Oblanceolate (Ob) type had largest SLA (117.2 cm2 g−1) and high dark respiration rate (Rd), but low TPTT and chlorophyll, which is important for shade adaptation in the lower canopy. Overall, LSI increased with the increases of LL, the higher value of TPTT, the greater value of P/S (Palisade/Spongy) was observed, and as the increases of LSP, PNmax gradually increased. Three principal components were extracted with a cumulative contribution of 75.2%, of which the Ov type had the highest value. Our findings provided evidence that the presence of heteromorphic leaf types facilitates the utilization resources of different microhabitat by L. coreana Levl. var. sinensis.