Growth and photosynthetic responses of the federally endangered shrub, Lindera melissifolia (Lauraceae), to varied light environments.

Photosynthetic, morphological, and growth responses to light environment can be useful measurements to determine favorable habitat conditions for the conservation of endangered species. For Lindera melissifolia (Walt.) Blume, we compared morphological and photosynthetic responses under natural and controlled light regimes, and growth under three light treatments: 100%, 42%, and 19% full sunlight. Typical sun-shade morphological responses to decreasing light levels included decreased stomatal density, increased specific leaf area, and increased leaf area ratio. Photosynthetic capacity (3-6 μmol CO(2) · m(-2) · s(-1)) was consistent with other shade-tolerant species. Light-saturated rates of photosynthesis of experimental plants increased with increasing light up to 42% sunlight, but declined at 100% sunlight. The 100% light treatment also resulted in lower plant biomass, primarily from a reduction in root biomass. Results indicate that canopy conditions at levels below 40% sunlight are optimal for plant growth and should be considered in management and reintroduction efforts for this species.