Effects of fire retardant chemical and fire suppressant foam on shrub steppe vegetation in northern Nevada

The objectives of this study were to determine the effects of fire retardan t chemical (Phos-Chek G75-F*) and fire suppressant foam (Silv-Ex) applicati on, alone and in combination with fire, on Great Basin shrub steppe vegetat ion. We measured growth, resprouting, flowering, and incidence of galling i nsects on Chrysothamnus viscidiflorus and Artemisia tridentata. These chara cteristics were not affected by any chemical treatment. We measured communi ty characteristics, including species richness, evenness, and diversity, an d number of stems of woody and herbaceous plants in riparian and upland plo ts. Of these characteristics, only species richness and number of stems/m(2 ) clearly responded to the chemical treatments, and the response was modifi ed by fire. In general, species richness declined, especially after Phos-Ch ek application. However, by the end of the growing season, species richness did not differ between treated and control plots. A canonical variate anal ysis suggested that burning had a greater influence on community compositio n than did the chemical treatments. In general, riparian areas showed more significant responses to the treatments than did upland areas, and June app lications produced greater changes in species richness and stem density tha n did July applications.