Ecological land classification as a surrogate for epigaeic arthropod biodiversity and conservation in boreal forest landscapes

The use of biodiversity surrogates offers a scientifically sound, robust, and cost-efficient approach for supporting conservation strategies over large landscapes. We examined the habitat associations of ground beetles, rove beetles, and spiders collected with pitfall traps from 12 undisturbed forest types that conform to different ecosites and ecophases using the ecosite classification system for the boreal mixedwood subregion of Alberta, Canada. A total of 79 578 epigaeic arthropods, representing 370 species, were collected during the summer of 2018. Catches of ground and rove beetles were highest in mesic deciduous forest stands, whereas spider catch was highest in subxeric, open canopy jack pine stands. Species richness and diversity differed among taxa and ecophases; however, evenness for the beetle assemblages increased along the moisture gradient, whereas, for spiders evenness was highest at both ends of the moisture gradient. Geographic location accounted for less variation among arthropod assemblages than ecosite and ecophase. In general, epigaeic arthropod assemblages reflected the environmental variation across the ecosite edatopic grid. Hence, the forest ecosite classification system can be used as a surrogate for epigaeic arthropod assemblage structure across large boreal forest mixedwood landscapes.