How mycorrhizal associations and plant density influence intra- and inter-specific competition in two tropical tree species: Cabralea canjerana (Vell.) Mart. and Lafoensia pacari A.St.-Hil.

摘要

Arbuscular mycorrhizal fungi (AMF) associations benefit host plants due to increased ability to obtain resources and hence may influence competitive interactions. Here we experimentally examine growth in Cabralea canjerana and Lafoensia pacari at different densities and with and without AMF. In the density treatment pots had either six or 12 individuals. Half of each treatment was innoculated with AMF and the other half was not. The proportion of each species in each pot was also varied. The AMF did not apparently influence interspecific competitive interactions because growth was similar in both treatments. However, intra-specific competition was very strong in C. canjerana while more moderate in L. pacari and both were influenced by the presence of the AMF. The AMF—Cabralea canjerana interaction was parasitic, while AMF—L. pacari interactions were mutualistic. Thus, dependence upon AMF and intraspecific interactions that result as a consequence of that dependence varies among species and may be an important influence in community structure.