Spatial relationships between spiders and their host vascular epiphytes within shade trees in a Mexican coffee plantation

Within tree canopies, vascular epiphytes create habitats for other taxa, and their heterogeneous spatial distribution could affect the distribution of organisms associated with them, such as spiders. This study was performed in shade trees of a rustic coffee plantation located within a Tropical Cloud Forest region of Mexico. We used a spatially explicit approach to examine (1) if the richness and abundance of epiphyte-dwelling spiders have a positive association with epiphyte abundance within trees and (2) if spiders (richness and abundance) show the same patterns of spatial distribution as the epiphytic habitat. We found that spiders were distributed on gradients of the same type as their host epiphytes. These gradients were: a decrease from the center toward the edges of the tree and a decrease from the base of the trunk toward the canopy. Spiders also had aggregation patches with similar dimensions to those exhibited by their host epiphytes. Those spiders' patches were fully explained when their epiphytic habitat was also aggregated within trees. Spatial models suggested that epiphytes and spiders were also spatially structured at scales larger than a tree and smaller than an epiphyte mat. Our findings demonstrate that the spatial distribution of epiphyte-dwelling spider communities, may partly be explained by the distribution patterns of their host plants. However, other environmental and biotic factors, not associated with epiphyte communities, are likely to be responsible for the remaining spatial patterns of spider distribution.