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Bodemverzuring in droog zandlandschap blijvend probleem
Roland Bobbink, Huig Bergsma, Jan den Ouden & Maaike Weijters
N-depositie, heide, bossen, herstelbeheer, steenmeel
Soil acidification: a continuous threat in the dry sandy regions of the Netherlands
Nitrogen deposition, forests, heathlands, restoration, rock powder
Many ecosystems of high conservation value, such as heathlands, acidic grasslands and deciduous woodlands are characteristic for the Pleistocene sandy areas of the Netherlands. Nowadays, most of them are restricted to nature reserves, including Natura 2000 sites. The biodiversity of these typical ecosystems has been severely affected by the impacts of atmospheric N (and formerly S) deposition since the 1970s. However, despite of the very strong reduction in S deposition in the last 3 decades, it has become clear that the impacts of atmospheric N deposition are still evident in ecosystems on dry, sandy soils. Recent studies have demonstrated that soil acidification still continues under the present N loads, regardless of its reduction in the period 1993 to 2004. It has led to base cation depletion, high aluminium and ammonium concentrations and very low levels of silicate minerals with base cations. Restoration of these degraded ecosystems on dry soils is very urgent, and innovative measures are under study to counteract soil acidification with experimental addition of ground silicate rocks (‘rock powder’). Furthermore, additional reduction of the N deposition is highly needed to prevent (re)degradation in the near future.