J. Glauninger, W. Holzner
Journal name not available for this finding
‘Interference’ has been proposed by Harper (1977) as a ‘blanket term’ comprising all ‘changes in the environment, brought about by the proximity of individuals’. It includes ‘neighbour effects due to the consumption of resources in limited supply’ (= competition sensu stricto), ‘the production of toxins’ (or better ‘chemical interaction’, Numata, Chapter 15), ‘or changes in conditions such as protection from wind and influences on the behaviour of predators’ or, as it often occurs in agrophytocoenoses, influence on the susceptibility to pests and diseases. Competition (sensu stricto) and allelopathy are two phenomena that can be separated easily theoretically and by experimental means, but it is very difficult to decide under natural conditions whether interference effects were brought about by a. or c. In most of the experimental results that will be reviewed in this chapter interference has been investigated under the term ‘competition’. Though we are aware of the contradiction (and agree with Harper) we decided to use ‘competition’ (sensu lato) here in this chapter for ‘interference’ as this is the common use in agricultural literature. It was also used in this sense in the previous chapter, to which ours is a supplementary one. As a second ‘excuse’ we should like to quote that in agrophytocoenoses competition for light, water and nutrients is by far the most important part of interference while allelopathy is playing a minor role, if at all.