Niche breadth and resource partitioning by four sympatric species of bark beetles (Coleoptera: Scolytidae).

Standing loblolly pines in southeastern North America are colonized by four sympatric species of bark beetles: Dendroctonus frontalis (Zimm.), Ips calligraphus (Germ.), I. grandicollis (Eichh.) and I. avulsus (Eichh.). The beetles compete for the limited amount of phloem tissue used as a site for reproduction. Using indices of niche breadth and niche overlap determined from the surface areas attacked, the interaction of colonizing beetle species in partitioning resources in entire trees and within each sample level was examined. The broadest niche breadth was exhibited by I. avulsus, while I. grandicollis had the narrowest. D. frontalis dominated the lower bole and overlapped primarily with I. calligraphus. The upper bole was similarly dominated by I. avulsus, which overlapped only slightly with D. frontalis, but overlapped extensively with I. calligraphus. Within tree species diversity was highest in the mid-bole sections and declined progressively toward the stump and top. Increasing species diversity showed a strong positive correlation with increasing mean niche overlap.