Exceptionally high mangrove root production rates in the Kelantan Delta, Malaysia; An experimental and comparative study

•A Malaysian mangrove forest shows exceptionally high annual root production of 12.7 t ha−1 yr−1.•Root productivity showed a strong seasonal trend, peaking during the monsoon season.•Root turn-over was exceptionally rapid (especially that of fine roots at 0.81 yr−1).•The root:shoot productivity ratio (at 2.65), was comparatively high.•Fine root biomass was the major contributor to belowground biomass and biomass production.