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.