Biomass accumulation in the endangered shrub Lindera melissifolia as affected by gradients of light availability and soil flooding
We studied the impacts of light availability and soil flooding on biomass accumulation and tissue biomass fractions in Lindera melissifolia (Walt.) Blume, an endangered woody shrub of the southeastern United States. Our experiment was located in a large-scale flooding research facility where plants were established and grown for three years while receiving combinations of 70%, 37%, or 5% of full sunlight with either 0, 45, or 90 days of soil flooding. We hypothesized that biomass accumulation would decrease with decreasing light availability and that soil flooding would further reduce plant mass. In the absence of soil flooding, shrubs receiving 37% light accumulated the greatest biomass (972 g), shrubs receiving 70% light were intermediate in biomass accumulation (737 g), and shrubs receiving 5% light accumulated the least biomass (14 g). Shrubs raised beneath 37% light had root biomass fractions less indicative of water stress than shrubs raised beneath 70% light, and leaf and stem biomass fractions less indicative of light deprivation than shrubs raised beneath 5% light. The light environment also influenced how soil flooding affected L. melissifolia biomass accumulation. Soil flooding had no detectable effect on the amount of biomass accumulated by shrubs acclimated to 5% light. However, shrubs acclimated to 70% or 37% light showed a 26% decrease in biomass accumulation after 90 days of soil flooding. Our findings demonstrate a responsive plasticity of L. melissifolia biomass accumulation relative to light availability and soil flooding, and this plasticity was driven by shifts among leaf, stem, and root biomass fractions. This plasticity supports development of silvicultural options for active management of this endangered species in floodplain forests of the Mississippi Alluvial Valley.