Coexistence of closely relatedEupatorium species. I.Eupatorium odoratum L. versusEupatorium adenophorum Spreng. andEupatorium adenophorum Spreng. versusEupatorium riparium Regel. at different altitudes

Abstract

At their altitudinal limits at 950 m elevation,Eupatorium adenophorum was more susceptible to density-dependent mortality but plasticity of individual organs including reproductive growth was more adversely affected inEupatorium odoratum. In mixtures,Eupatorium adenophorum had an edge overEupatorium odoratum suggesting that the former checks the upper altitudinal limit of the latter.Eupatorium adenophorum andEupatorium riparium coexist well in their mid-altitudinal range of 1500 m. In pure stands,Eupatorium adenophorum was more susceptible to density stress thanEupatorium riparium. Eupatorium riparium was more aggressive thanEupatorium adenophorum in the mixture of increased interspecific competition. In mixtures, these two sets of competing species are less affected than could be expected from the effect of crowding; they, perhaps, occupy different ecologic niches.