Dynamics of spider colonization of apple orchards from adjacent deciduous forest

The colonization of foliage-dwelling spiders into insecticide-free “micro” apple orchards at two distances (10 and 50 m) from an adjacent source habitat of deciduous forest was quantified in southern Québec, Canada. Both colonization rate and composition of colonizing spider assemblages were affected by distance at this small spatial scale: the samples from the micro-orchards 10 m from the forest were intermediate in composition between the assemblages in the deciduous forest and those in the micro-orchards 50 m from the forest. Spider species found in micro-orchards were the same as those documented from collections from older, insecticide-free orchards although species evenness was higher in the older orchards indicating that species composition shifts over time within the habitat. Maintaining deciduous forest near to orchards will provide a source of annual colonists for spider populations within the orchard.