Heterospecific mating and species recognition in the planktonic marine copepods Temora stylifera and T. longicornis

Smothering of many fringing coral reefs in Indonesia has led to mangrove colonization of the overlying soils in a process of human-induced succession. On the islands of Sulawesi and Sumatra, we measured some structural and functional attributes of 4 mangrove forests that have colonized such soil drapes.

The forests varied extensively in stem density, above-ground biomass, and in leaf area index. We estimated accumulation rates of above-ground forest biomass of 1.5 to 8.1 t C ha–1yr–1, similar to other mangroves. The ratio of greenhouse C and N emissions from soils averaged 35 compared with an average soil C:N ratio of 38.

Soil ammonification was sufficient to meet forest N demand. A value of 1 to 4% of soil C metabolism was involved in dissolving carbonate, with sulfate reduction being the major decomposition pathway. Rapid rates of N₂ loss were measured, but there was no detectable N₂O release. Rates of nitrogen fixation on the soil surface ranged from 97 to 1648 μmol N m–2d–1, but higher rates (860 to 4316 μmol N m–2d–1) were measured on microbial mats covering pneumatophores, suggesting N₂ fixation on above-ground tree parts may balance soil N₂ losses.

Rates of forest biomass accumulation related exponentially to rates of soil C and N metabolism, reflecting a close relationship between tree growth and nutrient availability as mediated by microbes in these shallow soils. These patterns are similar to those in other mangrove forests, and illustrate that human-induced change has resulted in a clear shift from reef-dominated to mangrovedominated habitats and functional characteristics in parts of coastal Indonesia.