Terrestrial arthropod communities are an integral part of a properly functioning ecosystem that is often overlooked in short-rotation woody crops (SWRC). These communities can act as harbingers of ecosystems overall health. Hybrid poplars in the Inland Northwest are a unique SRWC grown under drip irrigation on a 12-yr rotation within stringent Forest Stewardship Council (FSC) guidelines. The FSC emphasizes maintaining environmental quality and habitat when growing certified products. Because management decisions are continually evaluated during the 12-year rotation, a premium should be placed on identifying the components of this agroecosystem, specifically the insect community. We conducted a four-year investigation of the hybrid poplar terrestrial arthropod community prior to and following harvest to examine the impact of this planned catastrophe on the local insect community composition. Identifying the community composition, including the presence of pests and beneficials, allows for the development of management strategies that minimizes the overall environmental impact through pesticide application and planting strategies. Pitfall traps were utilized to monitor insect populations in newly planted and mature poplar stands, as well as the surrounding riparian and sagebrush habitats. Abiotic differences between these communities were quantified by recording above and below ground temperatures at the midpoint of each transect.
Surveys show that the terrestrial insect community consists of a number of pestiferous and beneficial insects; with a small suite of species dominating all observed communities. This suite of species includes both an omnivorous ground beetle (Calathus ruficollis Dejean, Coleoptera: Carabidae) and an ant (Tetramorium caespitum L, Hymentoptera: Formicidae). Newly planted stands and natural areas had the highest insect diversity (1-yr H’=1.74; Poles H’=2.36; Sagebrush H’=2.30; Riparian H’=2.52) and the mature stand the least diverse (H’=0.56). A similar trend in regard to evenness was also noted. The surface temperature within each community was closely tied to its apparent physical structure. Throughout the study sagebrush was the warmest habitat and closely mirrored by 1-yr old plantings while the mature stands were the coolest. Our findings suggest that the current management of hybrid poplars in the Inland Northwest under the FSC guidelines does provide suitable habitat for the local insect communities, although the suitability of these habitats may depend on age structure of the poplar stand. Further, this understanding of the insect communities of both the surrounding habitat and poplar stands has led to the development of a more complete integrated pest management strategy within this silvaculture.