Nitrogen deposition and grass encroachment in calcareous and acidic Grey dunes (H2130) in NW-Europe. (August 2017)

• Record Type: Journal Article
• Authors: Kooijman, A.M.; van Til, M.; Noordijk, E.; Remke, E.; Kalbitz, K.
• Is Part Of: Biological conservation. Volume 212:Part B(2017)
• Page Start: 406
• Page End: 415
• Publication Date: 2017-08
• Subjects: Atmospheric deposition -- Biodiversity -- Dune grasslands -- Mineralization -- Phosphorus; Conservation of natural resources -- Periodicals; Nature conservation -- Periodicals; Ecology -- Periodicals; Environment -- Periodicals; Environmental Pollution -- Periodicals; Electronic journals; 333.9516
• DOI: 10.1016/j.biocon.2016.08.009
• Languages: English
• ISSNs: 0006-3207

Abstract

Abstract: We present an overview of high nitrogen deposition effects on coastal dune grasslands in NW-Europe (H2130), especially concerning grass encroachment in calcareous and acidic Grey Dunes. The problem is larger than previously assumed, because critical loads are still too high, and extra N-input from the sea may amount to 10 kg ha − 1 yr − 1 . Grass encroachment clearly leads to loss of characteristic plant species, from approximately 16 in open dune grassland to 2 in tall-grass vegetation. Dune zones differ in grass encroachment, due to the chemical status of the soil. In calcareous and iron-rich dunes (Renodunal district), grass encroachment showed a clear gradient over the dune area. Grass encroachment is low in calcareous foredunes, due to low P-availability, and large grazers were not needed to counteract grass encroachment after 2001. In partly decalcified middle dunes, P-availability and grass encroachment are high due to dissolution of calcium phosphates, and grazing only partially helped to control this. In acidic, iron-rich hinterdunes, grass encroachment gradually increased between 1990 and 2014, possibly because P-availability increased with time due to increased soil organic matter content. In acidic, iron-poor dunes (Wadden district), grass encroachment is a large problem, because chemical P-fixation with Ca or Fe does not occur. Large grazers may however reduce tall-grass cover. High cumulative N-deposition could theoretically lead to increased N-storage and N-mineralization in the soil. Mineralization indeed increased with N-deposition, but in 15 N experiments, most ammonium was converted to nitrate, and storage in soil organic matter was low. Soil N-storage is probably reduced by high nitrate leaching, which will favour dune restoration when N-deposition levels decrease. Highlights: We review high N-deposition effects in NW-European Grey Dunes. Accurate estimates for critical loads and actual N-deposition are essential. Calcareous dunes are less sensitive to high N-deposition, due to low P-availability. Decalcified and acidic dunes are (much) more sensitive, due to high P-availability. High N-deposition does not lead to high N-storage in the soil, due to high leaching.