Dynamic Phenotypic Plasticity in Photosynthesis and Biomass Patterns in Douglas-Fir Seedlings

As climate changes, understanding the mechanisms long-lived conifers use to adapt becomes more important. Light gradients within a forest stand vary constantly with the changes in climate, and the minimum light required for survival plays a major role in plant community dynamics. This study focuses on the dynamic plasticity of Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) seedlings grown in contrasting light environments. Plasticity in Douglas-fir seedlings was primarily achieved by a combination of the physiological processes: maximum photosynthesis, quantum yield, Fv/Fm, Km (the light constant), light compensation point, and the ratio of needle area to needle weight (specific leaf area). Specific leaf area was the most plastic of the biomass parameters measured.