<Emphasis Type="Italic">Molinia caerulea</Emphasis> responses to N and P fertilisation in a dry heathland ecosystem (NW-Germany) |
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Authors: | Kirsten Falk Uta Friedrich Goddert von Oheimb Kerstin Mischke Konrad Merkle Hartmut Meyer Werner Härdtle |
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Institution: | (1) Institute of Ecology and Environmental Chemistry, University of Lueneburg, Scharnhorststr. 1, 21335 Lueneburg, Germany; |
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Abstract: | In the present study we analysed whether airborne N pollution may constitute one important driver for the encroachment of
Molinia caerulea in dry heathland ecosystems. Based on full-factorial field experiments (in 2006 and 2008) and complementary greenhouse experiments
(in 2008), we quantified growth responses of Molinia caerulea to N and P fertilisation (50 kg N ha−1 year−1, 20 kg P ha−1 year−1). Aboveground biomass production of Molinia
caerulea was limited by P in 2006, but by N in both experiments in 2008. In the greenhouse experiment, N addition caused a sixfold
increase of the biomass of vegetative tillers, and in all experiments the biomass and numbers of flowering tillers showed
a significant increase due to fertilisation. Our experiments indicated that growth of Molinia caerulea was primarily limited by N, but in dry heaths the kind of nutrient limitation may be mediated by other factors such as water
availability during the vegetative period. Shifts in biomass allocation patterns resulting from N fertilisation showed that
Molinia
caerulea encroachment in dry heaths is not only attributable to increased leaf biomass, but also due to higher investments in reproductive
tissue that allow for increased seed production and thus accelerated encroachment of seedlings in places where the dwarf shrub
canopy has been opened after disturbance. |
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