Dating Past Fires in Curlleaf Mountain-mahogany Communities

Abstract

Fire history was investigated in 4 curlleaf mountain-mahogany (Cercocarpus ledifolius) communities containing scattered, old ponderosa pine (Pinus ponderosa). Dating cross- sections of fire scars from the pines, through counts of annual growth rings, allowed us to develop reasonably complete fire chronologies extending back to the 1700's. Mean fire intervals in these communities ranged from 13 to 22 years until the early 1900's, but lengthened considerably thereafter. Mountain-mahogany stems with well-developed basal scars (not necessarily caused by fire) were cross-sectioned and finely sanded to enhance the often obscure growth rings. Estimated dates of the mountain-mahogany scars were compared to the pine-derived fire history. This evaluation suggests that where conifers of sufficient age are absent, careful interpretation of mountain-mahogany scars can be used to estimate fire history.