Year of Publication: 1979
Abstract:
Between August 18 and September 30,1978, insect communities of 12 homogeneous habitats, chosen as representative of the major vegetation types, were sampled in the Alberta Oil Sands Environmental Research Program (AOSERP) study area (56°21' to 58°00' N and 110°50' to 112°00' W). Soil and vegetation zones were quantitatively sampled, and insects and spiders collected were oven-dried and weighed. Additional samples were taken to show insect taxa present, relative abundance and vegetation damage levels. Collected insects were all determined to family level. The biomass of insects collected averaged 0.82 g oven-dry weight m-2 , and ranged from 0.28 (Jack Pine forest) to 3.11 (fen) grams. The majority of these were soil dwellers, as only 8% of the insect biomass was collected on foliage. Among the soil inhabitants, Diptera larvae were the group most commonly encountered, and contributed most to the biomass total. These were dominated by larvae of the families Fungivoridae (Mycetophilidae and Sciaridae), Chironomidae, Ceratopogonidae, and Anthomyiidae. Ants (Hymenoptera, Formicidae), were common in most habitats, and contributed significantly to the biomass total of several. Coleoptera and Lepidoptera were the third and fourth ranked contributors to biomass totals. Collembola, Heteroptera, Psocoptera, and miscellaneous insects were numerically abundant but did not usually contribute heavily to the biomass totals. The sites loosely followed a gradient of greatest biomass, numbers, and diversity in the wettest habitats, and lowest in the driest. Exceptions to this gradient were the wet black spruce bog, and the dry non-vegetated site. Spiders were abundant in all habitats, with standing crop biomasses from 0.03 to 0.20 g m-2. A total of 161 families of insects were found represented in the collections made. Specimens were collected of only four species of butterflies, Boloria titania Esper, Nymphalis j-album Boisduval, Polygonia satyrus Edwards, and Speyeria atlantis Edwards, while four other species were seen but not collected. The late start and short field period of this investigation dictate that these lists are not comprehensive. Insect damage surveys showed great variation in the rates of insect attack on dominant plant species. Leaves of Populus tremuloides Michx., were most heavily damaged, with an estimated 14. 7% of the leaf area removed. Leaves of Cornus stolonifera Michx. bore the greatest number of aphids, averaging 6.7 individuals per leaf. Few deciduous tree stems bore damage, except for galls on Salix sp., but galls and bud damage were common on spruce (Picea mariana (Mill.) and glauca (Moench) ). Insect caused crown and tree mortality was not significant. Trophic structure analysis showed that herbivores were the largest group of insects, followed closely by carnivores and an almost equa1 biomass of saprovores. Carnivores, which were mostly entomophagous, were over-represented in the quantitative samples due to their activity, while saprovores were under-represented. The ecological significance of the saprovore food chain is discussed as being a method of allowing protein concentration by microbes, which are consumed by these animals. The use of insects as environmental monitors is discussed, specifically for the AOSERP study area, including the outbreak potential of destructive bark beetles (Scolytidae).
