Tuesday, 18 November 2003: 4:30 PM
Postfire changes in understory composition in singleaf pinyon-juniper and Jeffrey pine alliances in the San Bernardino Mountains, California
Using direct and indirect ordination techniques, we related patterns of understory species composition to variables measuring elevation, slope, aspect, solar insolation, geologic substrate and burn intensity in plots taken after the Willow Fire in 1999. Herbaceous and shrub layers were analyzed separately but showed similar relationships to environmental variables. The first ordination axis of was significantly related to elevation. The second axis separated sites that burned from those that did not burn and indicated whether carbonate and non-carbonate plots differed in their response to fire. Lastly, we discuss the effects of burning on changes in species richness between substrates and discuss the presence of fire-stimulated plant species in conifer alliances that have a long average interval (>90 years) between fires.