Vortrag, AK Populationsbiologie der GFÖ, Freising: 01.05.2000 - 03.06.2000
Competition is one of the most important factors influencing plant population dynamics. This sometimes seems to be the one and only consensus in the fast-growing number of theoretical frameworks and experimental studies dealing with plant interactions. Long after the controversy between Grime and Tilman has been partially attributed to their different operational definition of competition (Grace & Tilman 1990), there is still much debate about how to design precise and powerful competition experiments and how to analyse the results in an appropriate way. Despite of this, most authors seem to agree on using just aboveground biomass data to calculate various competition coefficients.
However, particularly in unproductive environments where competition is primarily belowground, the quantitative measurement of belowground biomass might be crucial. In a controlled field competition experiment on sand with 3 early successional species we found significant differences in relative competition intensities (RCI) depending on whether the calculation of RCI was based on total biomass or aboveground data alone. In a review of the literature we will show several studies revealing similar results. The influence of these findings on the use of different measures to calculate competitive interactions will be discussed.