Juniperus osteosperma trees are mechanically shredded annually on hundreds of hectares of former Artemisia tridentata-dominated western-US lands by the Bureau of Land Management to reduce fuel loads and potential catastrophic wildfire. This mechanical shredding treatment leaves shredded needles, wood, and bark residue over preexisting canopy litter and interspace soil. We quantified total soil-CO₂ efflux from the surfaces of mechanically shredded and control (live J. osteosperma) microsite plots in a randomized complete block design using a Li-8100 Automated Soil CO₂ Flux System with the 8100-103 (20 cm diameter) survey chamber (LI-COR Biosciences, Lincoln, NE). Measurements were taken approximately 1 day after rainfall in Phase III (high density) J. osteosperma in the eastern Great Basin region of Utah.

Results/Conclusions

Preliminary results suggest that microsite plots with preexisting canopy litter or with canopy litter removed emit more CO₂ than either interspace microsite plots or interspace microsite plots covered with mechanically shredded residue. The greater total soil-CO₂ efflux from canopy litter influenced microsite plots may be due to greater soil organic matter. In addition, total soil-CO₂ efflux varies by season.