Vortrag, IAVS , Bilbao: 26.07.1999 - 30.07.1999
Most field studies calculated competition intensities either on the basis of aboveground biomass alone or projected data of soil cores for total root biomass. However, particularly in unproductive environments, where competition is primarily belowground, the quantitative measurement of belowground biomass is crucial. Here results are presented from a controlled field competition experiment on sand with Corynephorus canescens (L.), Carex arenaria (L.) and Hieracium pilosella (L.). Plants were grown in a randomized block design under two water and nitrogen regimes. To seperate belowground and total competition intensities different competition treatments were used. After 6 months above- and belowground biomass of the study plants were completely harvested and relative competition intensities (RCI) were calculated for the planted species combinations. While effects of the water and nitrogen treatment could only partly be detected, different RCI-values were obtained, depending on whether the RCI calculation was based only on aboveground biomass (as in most studies) or on belowground biomass.The consequences of these findings for the interpretation of aboveground biomass based RCI-values are discussed.