Fire Regime Alteration in Natural Areas Underscores the Need to Restore a Key Ecological Process

Abstract

Research Natural Areas (RNAs) are federal lands designated to protect exemplary, relatively undisturbed ecosystems where ecological processes may proceed unencumbered with minimal human intervention. Ideally, RNAs serve as properly functioning reference sites for more heavily managed landscapes. However, many RNAs have been modified to some degree by past and ongoing human actions. In the western United States, these actions commonly result in altered disturbance regimes, most notably fire. Ecological disturbance regimes are important components of natural ecosystems, and major changes to such regimes challenge the usefulness of the RNA system as a reference network. To assess the extent of modern departure from their pre-Euroamerican settlement (i.e., pre-1850) fire regimes, we examined 64 RNAs on Forest Service lands in California. We found that 76% exhibited moderate to high fire regime departure. Of these, 87% are burning much less frequently than they would have under the presettlement fire regime and 13% are burning more frequently. Within RNAs, ecosystems historically characterized by frequent, mostly low-severity fire have missed multiple fire cycles and tend to burn at higher fire severities than expected under the presettlement fire regime. We present four case studies that demonstrate how recent wildfires have affected California RNAs. We also indicate where and how future fire management strategies could address altered fire regimes and more effectively sustain target ecosystems within RNAs. Our findings suggest that a re-examination of the hands-off approach to management in some protected natural areas like RNAs is needed.