In March 2009, maritima published a recommendation for mangrove restorations that Brian Silliman and I wrote about in Ambio. We suggested that mangrove seedlings be planted in high densities clumps to reduce the harsh physical stress (anoxia and high salinity) of the intertidal environment, which can be lethal to mangrove seedlings. Both theory and experiments suggest that mangrove plants, ecosystem engineers that are capable of oxygenating the mucky forest floors of mangrove swamps, would respond well to being planted closer together, where they might facilitate each others' survival (i.e. positive density dependence).
Now, Mark Huxham and colleagues have shown that seedlings do survive better when planted at higher densities in field experiments! Their study appears in the July 12 issue of Philosophical Transactions of the Royal Society B: Biological Sciences. They found higher survival at higher density for the species Rhizophora mucronata at a low intertidal site in Sri Lanka and for the species Avicennia marina at a high intertidal site in Kenya.