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Fire has largely been excluded from many mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) communities. Land and wildlife managers are especially reluctant to reintroduce fire in mountain big sagebrush plant communities, especially those communities without significant conifer encroachment, because of the decline in sagebrush-associated wildlife. Given this management direction, a better understanding of fire exclusion and burning effects are needed. We compared prescribed burned to unburned control plots at six sites on the Hart Mountain National Antelope Refuge in Oregon. Burning generally increased soil nutrient availability, though not all measured soil nutrient concentrations varied between the burn and control plots. Plant diversity initially increased with burning, but then decreased. Burning altered the arthropod community, which included doubling the density of arthropods the first year after treatment. Some arthropod Orders increased and others decreased with burning. For example, Araneae (spiders) were 1.7- and 1.8-fold less and Hemiptera (true bugs) were 6.6- and 2.1-fold greater in the burn compared to the control in 2008 and 2009, respectively. Our results provide evidence that burning can create spatial and temporal heterogeneity in mountain big sagebrush communities and thus, it is an important component of the ecosystem. We suggest that management plans for many mountain big sagebrush communities may need to include infrequent burning. At the very least managers should be aware that fire exclusion has some potentially negative impacts other than the encroachment of conifers in these communities.
