Impact of sod-cutting and choppering on nutrient budgets of dry heathlands
Published source details
Niemeyer M., Niemeyer T., Fottner S., Härdtle W. & Mohamed A. (2007) Impact of sod-cutting and choppering on nutrient budgets of dry heathlands. Biological Conservation, 134, 344-353.
Published source details Niemeyer M., Niemeyer T., Fottner S., Härdtle W. & Mohamed A. (2007) Impact of sod-cutting and choppering on nutrient budgets of dry heathlands. Biological Conservation, 134, 344-353.
European heathlands characterised by dwarf ericaceous shrubs such as heather Calluna vulgaris, are endangered by increasing atmospheric nutrient deposition and natural succession. High-intensity techniques (e.g. sod-cutting) to remove nutrient rich topsoil is now necessary, as more traditional management (e.g. mowing, prescribed burning) does not compensate for atmospheric nutrient loads. This study compared the quantities of certain nutrients (N, Ca, K, Mg, and P) removed by sod-cutting or 'choppering' on a heathland in northwest Germany; specifically, to what extent does choppering and sod-cutting affect nutrient budgets in dry heathlands. Choppering (i.e. the near-complete removal of the organic layer) has several advantages over sod-cutting, including less waste material, faster vegetation recovery and lower cost.
Study area: The study was undertaken at Lueneburg Heide (Lueneburg Heath nature reserve), a large complex of heathlands (about 5,000 ha) in Lower Saxony, north-west Germany (105 m a.s.l.). Sandy and nutrient-poor podzols with topsoil pH ranging between 3.3 and 3.5, are characteristic of the area.
Experimental design: Within 100 ha area of dry heathland, 18, 20 m — 20 m plots was randomly selected; nine were choppered and nine sod-cut. The plots were on similar areas of dry heathland (i.e. similar organic layer thickness, vegetation structure, Calluna 10-12 years age, unmanaged for 10 years) dominated by Calluna, wavy hair-grass Deschampsia flexuosa and purple moor-grass Molinia caerulea.
Nutrients in above-ground biomass and soil were analysed in the plots before and after management. A leaching experiment was carried out on four plots in each treatment. For the leaching experiment, control plots (also 20 m — 20 m) where there was no management were also established adjacent to plots used for the leaching experiment.
Management: Choppering and sod-cutting were carried out in December 2001 and January 2002. Choppering (undertaken using a machine equipped with sledges) created bare soil by removing vegetation and most of the O-layer, with only a thin layer of organic material remaining. Sod-cutting created bare soil by removal of vegetation, O-layer and parts of the A-horizon; after which sandy mineral soil formed the surface.
Soil nutrient balance: Nutrient balances were calculated by analysing atmospheric inputs, elevated leaching rates following management, and output due to the removal of above-ground vegetation and humus soil (O- and A-) horizons.
Atmospheric N-input was calculated to be 22.8 kg/ha/yr; P-concentrations were too low to be analysed (i.e. <0.5 kg/ha/yr). Nutrient loss was high after removal of the humus-rich O- and A-horizons. In contrast, increased leaching observed subsequent to choppering and sod-cutting was of minor importance for nutrient budgets. Considerably more nutrients were removed by sod-cutting than by choppering (e.g. 1,712/kg/ha and 1,008/kg/ha N removed respectively). However nutrient reduction by choppering still compensated for an estimated 61 years of net N-input.
As choppering removed more N per volume unit than sod-cutting (due to higher N-content in the organic layer than in the A-horizon), it worked out as more economical than sod-cutting in reducing soil nutrient loads.
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