Nutrient input from hemiparasitic litter favors plant species with a fast-growth strategy

Hemiparasitic plants often produce nutrient-rich litter with high decomposition rates, and thus can enhance nutrient availability. When plant species have differential affinities for this nutrient source, hemiparasitic litter might influence species composition in addition to the parasitic suppression of host species. We expected that species adapted to fertile habitats derive a higher proportion of nutrients from the hemiparasitic litter compared to other species. N-15-labeled litter of Rhinanthus angustifolius and Pedicularis sylvatica was added to experimental field plots and adjacent litter bags. We examined N release from the litter, N uptake by the vegetation 2, 4 and 12 months after litter addition and differences in the proportion of N taken up from the litter (N-L) between co-occurring species. The percentage of N in shoots of co-occurring plant species that is derived from the added hemiparasitic litter (N-L) strongly differed between the species (0.1-6.2 %). After exclusion of species with an alternative N source (legumes as well as ectomycorrhizal and ericoid mycorrhizal species), N-L was positively related (p < 0.001) with specific leaf area (SLA) and at Pedicularis sites with leaf N concentration (LNC) and leaf phosphorus concentration (LPC) (p < 0.05), i.e. leaf traits associated with a fast-growth strategy and adaptation to high-nutrient environments. Our results suggest that nutrient release from hemiparasitic litter favors plant species with a fast-growth strategy adapted to high-nutrient environments compared to species with a slow-growth strategy. Whether continued hemiparasitic litter inputs are able to change species composition in the long term requires further research.