Arthropod Diversity in Contrasting Ontario Peatlands

Peatlands are important wetland systems, but dominant macroarthropod groups endemic to peatlands and the environmental factors that affect them are poorly represented in the literature. I examined the richness, abundance, and community composition of soil and surface dwelling macroarthropods using emergence traps, peat sorting, and pitfall traps in two Ontario fens differing in water table, nutrient level, and vegetation. I found 218 arthropod morphospecies, with each site having a similar richness of emergent arthropods, but patterns of community composition differed between the two sites. The Carex (sedge) dominated site had twice as many emergent individuals, and total abundances declined dramatically over the growing season, whereas the Sphagnum (moss) dominated site had consistent arthropod abundances. Seasonal change in soil moisture was a significant correlate of arthropod abundance. Since Canadian peatlands face increasing climate warming, this study provides baseline information on the resident macroarthropod communities in different peatland types

Spatial covariance of herbivorous and predatory guilds of forest canopy arthropods along a latitudinal gradient

In arthropod community ecology, species richness studies tend to be prioritised over those investigating patterns of abundance. Consequently, the biotic and abiotic drivers of arboreal arthropod abundance are still relatively poorly known. In this cross-continental study, we employ a theoretical framework in order to examine patterns of covariance among herbivorous and predatory arthropod guilds. Leaf-chewing and leaf-mining herbivores, and predatory ants and spiders, were censused on > 1000 trees in nine 0.1 ha forest plots. After controlling for tree size and season, we found no negative pairwise correlations between guild abundances per plot, suggestive of weak signals of both inter-guild competition and top-down regulation of herbivores by predators. Inter-guild interaction strengths did not vary with mean annual temperature, thus opposing the hypothesis that biotic interactions intensify towards the equator. We find evidence for the bottom-up limitation of arthropod abundances via resources and abiotic factors, rather than for competition and predation.publishedVersio

Spatial covariance of herbivorous and predatory guilds of forest canopy arthropods along a latitudinal gradient

In arthropod community ecology, species richness studies tend to be prioritised over those investigating patterns of abundance. Consequently, the biotic and abiotic drivers of arboreal arthropod abundance are still relatively poorly known. In this cross-continental study, we employ a theoretical framework in order to examine patterns of covariance among herbivorous and predatory arthropod guilds. Leaf-chewing and leaf-mining herbivores, and predatory ants and spiders, were censused on > 1000 trees in nine 0.1 ha forest plots. After controlling for tree size and season, we found no negative pairwise correlations between guild abundances per plot, suggestive of weak signals of both inter-guild competition and top-down regulation of herbivores by predators. Inter-guild interaction strengths did not vary with mean annual temperature, thus opposing the hypothesis that biotic interactions intensify towards the equator. We find evidence for the bottom-up limitation of arthropod abundances via resources and abiotic factors, rather than for competition and predation