To gain knowledge about carbon and nitrogen mineralization potentials and their interaction with sandy soil environment in tropical dry coastal ecosystems, we carried out a short-term laboratory incubation experiment. For this, soil surface (0-10 cm) samples were collected from tropical semi-deciduous forest (TSdF), secondary forest (SecF), coastal dune scrub_crest (DS_C), and coastal dune scrub_slack (DS_S). Soil samples were incubated at 25 degrees C with constant soil moisture (at field capacity) for 97 days, and over this time 10 and 11 sampling occasions were analyzed to determine carbon (CO2-C) and nitrogen (NH4+, NO3-) dynamics, respectively. We used a simple exponential model to estimate soil carbon and nitrogen mineralization pools. On average, soil organic carbon mineralization rates ranged between 0.017 and 0.053 mg CO2-C g(-1) soil d(-1) and varied in the following order: DS_S > SecF > TSdF > DS_C. Average net mineralization rates (mg N kg(-1) soil d(-1)) ranged between 16.9 and 18.8 and varied in the following order: SecF > DS_S > TSdF, whereas in DS_C it was -0.44, indicating N immobilization. Co and No represented, on average, 1.08% and 5% of soil organic carbon and total organic nitrogen, respectively. On average, mineralization constants (k) for Co and No were 0.29 d(-1) and 0.23 d(-1), respectively, showing that SOM is easily mineralized. The proportion of NO3-/N-m was very high in SecF (89%) and TSdF (75%), while DS_C showed nitrate immobilization. The increase in NO3-/N-m ratio in SecF could be associated with legume species that have established in the nature restoration (SecF) on ex-grassland. Across all study sites, linear regression analyses suggested that soil physical and chemical properties may regulate SOM mineralization (p < 0.05).
