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 retardant chemical (Phos-Chek G75-F*) and fire suppressant foam (Silv-Ex) application, alone and in combination with fire, on Great Basin shrub steppe vegetation. We measured growth, resprouting, flowering, and incidence of galling insects on Chrysothamnus viscidiflorus and Artemisia tridentata. These characteristics were not affected by any chemical treatment. We measured community characteristics, including species richness, evenness, and diversity, and number of stems of woody and herbaceous plants in riparian and upland plots. Of these characteristics, only species richness and number of stems/m2 clearly responded to the chemical treatments, and the response was modified by fire. In general, species richness declined, especially after Phos-Chek application. However, by the end of the growing season, species richness did not differ between treated and control plots. A canonical variate analysis suggested that burning had a greater influence on community composition than did the chemical treatments. In general, riparian areas showed more significant responses to the treatments than did upland areas, and June applications produced greater changes in species richness and stem density than did July applications.