Decomposition and elemental release of leaf litter in Kandelia obovata mangrove forests under different sea level rise scenarios

Abstract

Leaf litter decomposition is an important source of carbon and nutrients to mangrove soil and fauna, and adjacent costal ecosystems. Mangrove forests are extremely sensitive to sea level rise which may affect leaf litter decomposition. Seasonal decomposition and elemental release (i.e., carbon, nitrogen and phosphorous) of leaf litter were investigated at three Kandelia obovata mangrove sites with different tidal elevations, such as RSL (rising sea level) 0 cm, RSL 40 cm and RSL 80 cm, simulating the sea level rise scenarios by 0 cm, 40 cm and 80 cm, respectively. Half-time (T50) of leaf litter decomposition was 31.4 d in spring, 17.3 d in summer, 15.1 d in autumn and 35.1 d in winter. Mean decomposition rate and dry weight loss rate of leaf litter at site RSL 0 cm were obviously higher than values at sites RSL 80 cm and RSL 40 cm, with annual mean T50 values of 21.4 d, 30.7 d and 30.3 d at sites RSL0 cm, RSL 40 cm and RSL 80 cm, respectively. Elemental releases of leaf litter were very similar to dry weight loss rate and site RSL 0 cm had significantly higher elemental releases. These indicated that sea level rise will decrease decomposition and elemental release of mangrove leaf litter.