Biotic factors associated with the spatial distribution of the mistletoe <em>Psittacanthus calyculatus</em> in a tropical deciduous forest of central Mexico

Abstract

Psittacanthus calyculatus (DC.) G. Don (Loranthaceae) is a neotropical hemiparasitic mistletoe and one of the most abundant and widely distributed species of the genus. Like most mistletoes, the interaction with its hosts and dispersers are directly related with its distribution and community dynamics. For the last decade, the infested areas in central México have increased, becoming a potential plant health problem. The aim of this study was to investigate three main biotic factors associated with the distribution of P. calyculatus in a tropical deciduous forest: (1) the plant community structure, (2) the host spatial distribution and level of association with P. calyculatus, and (3) bird consumers. Modified Whittaker plots were used to analyze the structure and composition of the plant community, comparing a highly infected mistletoe sites with non-infected sites. The spatial distribution and association of P. calyculatus with its most frequent hosts were calculated through a spatial analysis by distance indices. Study sites differed in plant diversity and species composition, showing a positive relation of mistletoe abundance with low diversity sites. The distance indices analysis presented a clumped distribution of P. calyculatus and Acacia hosts, as well as a high association with leguminous species such as A. farnesiana (X = 0.31, P = 0.0041) and A. schaffneri (X = 0.3977, P = 0.001). Three species consumed P. calyculatus’ berries: the Northern mockingbird, the Silky-Flycatcher and the Scott’s Oriole.

Keywords

• dispersers
• distance indices
• host association
• Psittacanthus calyculatus
• spatial distribution