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

• Published in: Forest ecology and management Vol. 444; pp. 214 - 224
• Main Authors: Muhammad-Nor, Siti Mariam, Huxham, Mark, Salmon, Yann, Duddy, Symone Jade, Mazars-Simon, Alban, Mencuccini, Maurizio, Meir, Patrick, Jackson, Gail
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.07.2019
• Subjects: Allocation aboveground; Allocation belowground; Monsoon season; Rapid root turnover; Root production; Root stock; Allocation belowground; Allocation aboveground; Monsoon season; Root production; Rapid root turnover; Root stock
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2019.04.026

•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. Mangroves often allocate a relatively large proportion of their total biomass production to their roots, and the belowground biomass of these forests contributes towards globally significant carbon sinks. However, little information is available on root production in mangroves due to the difficulties in carrying out measurements of belowground processes, particularly if there is regular flooding. In this study, we examined fine and coarse root production in the east coast of the Malaysian Peninsula. Ingrowth cores were used over the course of 17 months. In September 2014, twenty cores were randomly placed in each of five plots. Three cores were collected from each plot (fifteen cores in total), once every three months. Each core was divided into five 10 cm layers and root dry mass was recorded. Standing root biomass was also measured at the time of final collection using an additional 15 cores. There was a seasonal pattern in root production, which peaked in March and December 2015, after and during the monsoon season. Root biomass in the cores peaked at 33.23 ± 6.3 t ha−1 and 21.46 ± 7.3 t ha−1 in March and December respectively. Standing root biomass in February 2016 in the forest was 20.81 ± 2.8 t ha−1. After 17 months, the final root biomass in the cores was 14% less than the standing root biomass. These data suggest surprisingly rapid growth rates and turnover for mangrove roots. Total root biomass significantly increased with root depth and 78% of the roots, in all soil layers, consisted of fine roots (<3 mm diameter). Soil carbon, nitrogen and phosphorous concentrations were investigated in relation to belowground production, as were soil temperature, salinity and dissolved oxygen. A data review of global studies reporting similar work was carried out. The results are discussed with consideration to the significance of monsoon rainfall for mangrove ecology.