Vortrag, International Association for Vegetation Science (IAVS), Freising: 29.07.2001 - 04.08.2001
“The interpretation of the outcome of competition can depend critically on the way competition is measured” (Freckleton 1999). This statement is easily applicable to different levels of “measurement” in competition experiments. Selection for appropriate designs is already a demanding task, particularly in front of the recent debate about the use of different experimental designs for the investigation of plant competition. Moreover, the response variable, either on a single plant or population level, as well as the time scale to measure parameters needs to be thoroughly considered. Likewise the effect size selected for data presentation might significantly influence its interpretation. Use of competition indices to measure interaction strength between species can facilitate the presentation of experimental results and may help to compare results of different studies. On the other hand, the melting of several variables into an index will result in some loss of information, in the obscuring of relationships and in a decrease in statistical precision (Jolliffe 2000). The intention of the talk is to briefly discuss some of these problems based on own data from experiments with species from early successional stages on inland dunes.
Freckleton,R.P & Watkinson,A.R. (2000) J.Ecol. 88(3). Jolliffe,P.A. (2000) J.Ecol. 88(3).