Poster, AK Populationsbiologie der GfÖ, Regensburg: 20.05.2004 - 22.05.2004
The introduced Indian Strawberry, Duchesnea indica (Andr) Focke, shows an increasing invasive potential in the Ecological-Botanical Gardens of the University Bayreuth, Germany. There, it grows vigorously on a broad range of varying site conditions including those of the native Wild Strawberry, Fragaria vesca L. Both species appear to be similar in growth and reproductive strategies. Still, the increasing spread of Duchesnea might be one indicator of its high competitive effect and the potential risk of replacing the native Fragaria. Our study compared the competitive strength of both species in differing light conditions (full sun, half shade and shade) in a field experiment. The results revealed differences in the vegetative growth that might become important for competitive interactions especially on a longer time scale. Fragaria has a strategy of ‘space capturing’, forming long stolons with delicate daughter ramets at the end. In contrast, Duchesnea has robust daughter ramets growing in short distances on the stolons and form a dense carpet (‘space occupation’). Competing plants of both species showed an average 75 % total biomass reduction compared to control plants. Other than biomass, competition lead to a significant reduction in the number of daughter ramets, total stolon length and total leaf area of both species, but particularly so for Fragaria in half shade and shade. In full sun the effect of competition on both study species was the same. Overall, the results indicate a higher competitive effect of Duchesnea mainly in half shade, while Fragaria showed a high and flexible competitive response.