XVI International Botanical Congess

Sediment blockage and subsidence have led to increased hydroperiod at lower elevations in SE Louisiana. We expect variation in hydrology following a subtle topographic gradient will strongly influence the depth distribution, dynamics and production of fine roots. We sampled this forested transect in 2 seasons at depths from 0-50 cm. During the summer total fine root length and biomass in the top 50 cm are greatest at the lowest elevation. Fine roots diminish rapidly with depth, with >60% of fine root length located in the top 10 cm. At higher elevations more fine roots are located between 10-50 cm depth. Fine root standing crop is highest at intermediate soil water contents, decreasing as soils become saturated and as they dry. We explore the implications for NPP in coastal forested wetlands where rising relative sea level is leading to increased hydroperiod.