REGULAR ARTICLE Nitrogen uptake and utilisation as a competition factor between invasive Duchesnea indica and native Fragaria vesca Johanna Littschwager & Marianne Lauerer & Evgenia Blagodatskaya & Yakov Kuzyakov Received: 29 July 2009 / Accepted: 17 November 2009 / Published online: 10 December 2009 # Springer Science+Business Media B.V. 2009 Abstract The Indian mock strawberry [Duchesnea indica (Andrews) Focke] is an invasive plant in several regions of central Europe and Germany. In order to explore its competitive ability, we compared it with the native woodland strawberry (Fragaria vesca L.) by growing it alone as well as in intra- or inter-specific competition in a pot experiment under greenhouse conditions. Nutrient solution was added several times at two nitrogen (N) levels. One addition involved 15 N labelling to determine whether the competition of both plant species depends on their ability to acquire N from soil. Duchesnea had a higher biomass production than Fragaria when grown in nutrient-rich soil, both in competition and as a solitary plant. Under N-poor conditions, root interference could change this superiority due to limited soil space. After 65 days of growth, total plant dry weight, total N content and 15 N content in the plant tissues were determined. The results show that the predom- inance of Duchesnea in biomass production was confirmed at high, but not at low N availability. The assimilate partitioning strategy of Duchesnea differs from that of Fragaria: the former generally had a higher shoot-to-root ratio. The N content in shoots and roots was affected only by N addition but not by competition or species. Duchesnea allocated more N to the leaves, Fragaria to the roots. The amount of 15 N taken up was nearly equal for both species. In relation to root biomass, Duchesnea had a higher specific uptake rate at low N addition because of the higher root biomass in Fragaria. The roots of Fragaria and Duchesnea did not affect each other when grown together. We conclude that the invasive potential of Duchesnea is only poorly related to the N uptake rate or to better root competition for N. In N- rich environments, however, Duchesnea is highly competitive because of the preferred investment in shoot biomass. Therefore, environments with in- creased N deposition, i.e. from anthropogenic sources, could promote the invasive potential of Duchesnea. Keywords N utilisation . Duchesnea indica . Fragaria vesca . 15 N uptake . Competition strategies . Invasive species Introduction The Indian mock strawberry [Duchesnea indica (Andrews) Focke] is a locally invasive plant in central Europe. Its spontaneous distribution in Germany, Plant Soil (2010) 331:105–114 DOI 10.1007/s11104-009-0236-2 Responsible Editor: Herbert Johannes Kronzucker. J. Littschwager (*) : E. Blagodatskaya : Y. Kuzyakov Department of Agroecosystem Research, BayCEER, University of Bayreuth, 95440 Bayreuth, Germany e-mail: johanna.littschwager@gmx.de M. Lauerer Ecological-Botanical Gardens, University of Bayreuth, 95440 Bayreuth, Germany