The higher availability of N and P in lime‐poor than in lime‐rich coastal dunes in the Netherlands

Abstract

Summary1 Measurements of above‐ground productivity, plant nutrient levels, in situ mineralization and litter decomposition in four localities differing in soil chemical conditions were used to assess the availability of N and P in Dutch coastal dune grasslands.2 P‐availability is regulated by soil chemical conditions and seems to be a key factor regulating biomass production, whereas N‐availability seems to be determined by litter input from this biomass, and thus indirectly controlled by P.3 Contrary to expectation, N‐availability is much higher in acid soils (with low rates of decomposition and high soil C : N ratios) than in calcareous soils (with high decomposition and low C : N ratios). Similar results have been reported from other ecosystems and may be due to a lower microbial N‐demand at low rates of decomposition, increasing the amount of N left over for the vegetation.4 In contrast to ‘conventional wisdom’, low‐degradable litter may be a good plant strategy to improve the ecosystem recycling of nutrients and increase their availability. This may at least partly explain the success of Ammophila arenaria in lime‐ and iron‐poor dunes.