Litter Decomposition in a Coastal Dune Slack

Abstract

The rates of decomposition of buried and unburied litter of four dominant plants were measured over a 2 year period in coastal dune slacks. The plants were the composites Gazania rigens and Arctotheca populifolia, the grass Sporobolus virginicus and the rush Juncus krausii. Decomposition in all cases was faster in buried litter bags than in those on the surface, 50% decomposition taking 40-50 and > 125 weeks, respectively. Further, surface bags with large apertures, to enable the entry of macrofauna, showed the same decomposition rates as bags with small apertures. Exponential decay coefficients were 0.06-0.29y ^-1 above ground and 0.38-0.86y ^-1 below ground. Nitrogen contents of all bags showed increases to peaks of 160-400% initial values at 15-30 weeks. Thereafter nitrogen levels dropped, probably because of the hot dry conditions of summer (40-75 weeks), followed by another increase at 126 weeks to peaks of 140-350%.