Technical Abstract: The linkages between aquatic and terrestrial systems are ecologically inseparable, yet little is known about upland agricultural soil invertebrate composition and its contribution to aquatic Pacific Northwest ecosystems. Using Burlese-Tullgren extractors, soil-borne invertebrates were identified from the upper 30 cm of soil in 5 cm increments every other week for one year in an undisturbed Festuca rubra L. grass seed ecosystem in the Silverton Hills, Oregon, U.S.A. Species diversity was great with 10 Collembola genera, 98 Acari morpho-species, and 104 other invertebrate taxa comprising 19, 71, and 10% of the total number of specimens, respectively. Sampling the top 5 cm of soil was most informative. Some arthropod temporal patterns were correlated with abiotic factors such as the collembola Lepidocyrtus (fam. Entomobryidae) with soil temperature in summer and Isotomidae and Hypogasturidae families in winter, indicating similar spatial but separate temporal niches. Invertebrate populations also span different but linked trophic levels as indicated by positive correlations of Armidillidium vulgar to root/littler biomass amount and predacious Gamasida mites with Hypogasturidae prey number. These findings will identify key taxa, abiotic factors, and spatial and temporal templates for analyses linking soil invertebrates transported by overland flow or flooding to aquatic ecosystem food webs.