Response of forest soil Acari to prescribed fire following stand structure manipulation in the southern Cascade RangeThis article is one of a selection of papers from the Special Forum on Ecological Studies in Interior Ponderosa Pine — First Findings from Blacks Mountain Interdisciplinary Research.

Abstract

We studied responses of Acari, especially oribatid mites, to prescribed low-intensity fire in an east side pine site in the southern Cascade Range in California. We compared oribatid population and assemblage responses to prescribed fire in stands that had been selectively logged to enhance old growth characteristics, in logged stands to minimize old growth characteristics, and in undisturbed forest reference stands. Low-intensity prescribed fire altered habitat characteristics within the organic layer of forest soil. Acarine populations declined following prescribed fire, and oribatid losses accounted for two thirds of that decline. Individual oribatid species responded differently to prescribed fire, with a few populations increasing after fire but most declining. The prescribed fire also altered oribatid assemblages, reducing species richness and species diversity and modifying assemblage dominance relationships. We also identified several oribatid taxa that were potential indicator species of fire effects upon forest soil fauna. Finally, our results suggested that oribatid responses to fire were intensified by stand alteration and especially by removal of old growth structural characteristics. Decline in oribatid abundance, species richness and diversity, and loss of equilibrium dominance relationships was greatest in the low structural diversity plots.