9527663 SNIDER In situ observations of collembolan populations in the root zone of Michigan agroecosystems have provided reliable evidence that conventional sampling methods severely underestimate population densities and cannot adequately document vertical distribution and activity of Collembola throughout the root profile. Evidence from microvideo recordings indicates that Collembola range to depths of >100 cm in large numbers, and that collembolan and root demographics may be correlated over space and time. Based on data which suggest the existence of much larger populations than previously estimated (populations which persist and are active throughout the water), the PIs propose that the magnitude of collembolan influence on carbon cycling may also have been underestimated. This project will quantify the demographics of Collembola / root associations in the field, and document potential mechanisms underlying these associations. In addition, the work will assess potential effects of collembolan activity in the root zone on carbon flow through below-ground trophic networks. The work is directly linked to ongoing NSF/LTER research at Kellogg Biological Station, which focuses on ecological properties of natural and managed ecosystems, and on the mechanisms which regulate interactions in these systems. The research will also add significantly to current understanding of below-ground interactions, by documenting distribution and activity of a major soil faunal component, the nature of its association with roots and rhizospheres, and the magnitude of its effect on carbon cycling within below-ground trophic networks.