top of page


A Comparative Invertebrate Study of Oregon Military Department Installations in 3 Ecoregions – Assessment of Assemblages and Sampling Mythologies


Jeff Barna, Senior Biologist/Research Ecologist, Environmental Science Associates:

Jim Arnold, Environmental Branch Chief, Oregon Military Department – Installations Division (AGI):


The Coast Range, Willamette Valley, and Columbia Plateau are three distinct Oregon ecoregions. A frequently overlooked, but essential ecological component is the invertebrate assemblage present. Invertebrates interact with vegetation, wildlife, and organic matter and substantially shape habitats in which they reside. They are pollinators, decomposers, herbivories, predators, and prey. They support protected species, and are themselves, protected species. Documenting invertebrate assemblages provides important understanding into ecosystem health and resilience, and important data for Installation management. Invertebrates were studied at three OMD installations: Camp Rilea (Coast Range), Najaf Training Center (Willamette Valley), and Camp Umatilla (Columbia Plateau) with the goal of documenting invertebrate assemblages at each. The study approach was built on management objectives and characteristics of each installation, by identifying taxa of interest with potential to occur, types and distributions of habitats and microhabitats, and Military facilities and objectives. With this understanding, a general comparative study approach was established, which allowed tailoring for each installation. Concurrent studies were conducted at the three installations that accounted for seasonal changes and unique habitat features and management needs. Survey locations were selected to ensure representative coverage of habitats and an even spatial distribution. Because many invertebrates interact with their environment at a small spatial scale, microhabitats were specifically sampled. Methods focused on "guilds" based on shared characteristics important to detection: timing of peak activity (time of day, season); primary mode of transport (flying, swimming, burrowing, walking); and associated habitats and habitat features (microhabitat). Habitat features within each habitat included vegetation, decomposing organic matter, sub-surface within soils, on soil substrate, and aquatic features. A combination of standard techniques and secondary observations were used. This approach insured that all taxa of interest and habitat features of interest were specifically targeted. Findings indicate unique invertebrate assemblages are present at each installation and are influenced by habitats present, site history, and ongoing management. They, in turn, inform both natural resource management and operations at each Installation. An adaptive, scientific approach was essential to successful study, allowing adjustments to optimize study design. Other important factors in the study included incidental observations, maximizing time spent in each survey area, staffing with observant biologists, and using efficient data collection tools. Survey limitations existed but were largely overcome by adaptiveness of the study design.

bottom of page