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

Abstract

Summary 1Measurements 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.

Changes in nutrient availability from calcareous to acid wetland habitats with closely related brown moss species: increase instead of decrease in N and P

“…In mineral-poor fens, however, biomass and plant nutrients decreased again. In dune grasslands, this decrease seemed mainly due to P-fixation in iron phosphate (Kooijman and Besse 2002), but in the mineral-poor fens of this study, with low iron contents, iron phosphates were probably unimportant. Biomass decreased from intermediate to poor fens, despite a further increase in net mineralization of N and P. Aboveground biomass may have been reduced by Al-toxicity (Zvereva et al 2007), or to some extent by Fe-toxicity (Rozbrojova and Hajek 2008), even though iron contents were relatively low.…”

“…Although Bayley et al (2005) reported that decomposition rates were significantly correlated with the mean daily net N mineralization rate, many studies actually measured high net mineralization in acid peatlands, and low values under mineral-rich conditions (Verhoeven et al 1988(Verhoeven et al , 1990Scheffer et al 2001;Paulissen et al 2004). Also, Bridgham et al (1998) found a rapid turnover of the nutrient pools in ombrotrophic sites, despite low total soil N and P. High instead of low net mineralization under acid conditions has also been reported for field and laboratory studies in forests (Zöttle 1960;Davy and Taylor 1974;Kooijman et al 2008) and coastal dune grasslands (Kooijman and Besse 2002).…”

“…Similar to coastal dune grasslands (Kooijman and Besse 2002), aboveground biomass in fens showed an optimum at intermediate pH, associated with an increase in net mineralization of N and P. In intermediate fens, biomass and plant nutrients may increase by dissolution of calcium phosphate, and higher efficiency of mineralization per unit microbe. In mineral-poor fens, however, biomass and plant nutrients decreased again.…”

Low Atmospheric Nitrogen Loads Lead to Grass Encroachment in Coastal Dunes, but Only on Acid Soils

“…One is that surplus mineralized N is taken up directly by Carex. In addition, in acid soils more N might be available for vascular plants in competition with microbes as microbial communities seem to have a lower demand for N (Kooijman and Besse 2002;Kooijman and others 2008). Another possible explanation is, that NO 3 -, which is not taken up, is readily leached.…”

Effects of nitrogen deposition on soil and vegetation in primary succession stages in inland drift sands

“…The gramenoid Carex arenaria was mainly found in sites with high N deposition. In lime-poor coastal dunes, C. areneria is the main threat to species-rich pioneer vegetation as its leaf litter decomposes slowly (Kooijman and Besse 2002).…”