THE PATTERN OF SOIL VARIABLES RELATED TO ARTEMISIA-TRIDENTATA IN A BURNED SHRUB-STEPPE SITE

Artemisia tridentata Nutt. is a prominent shrub of cool deserts in the USA that influences the patterns of chemistry and microbiological act ivity in the soil in which it grows. However, little is known about th e fate of these patterns following the death or removal of the live A. tridentata plant. We compared abutting burned and unburned sites to s ee if patterns in soil could be related to locations where shrubs were removed by fire 9 yr earlier. While most soil variables were signific antly higher in the unburned site than in the burned site, total organ ic C and soil pH appear unaffected by the removal of A. tridentata or the fire itself. Differences between unburned and burned sites were gr eatest near the location of a plant axis. In contrast, burned soil was not distinguishable from unburned soil at distances greater than appr oximate to 50 cm away from a live A. tridentata axis or a charred stum p indicating that soil patterns were most affected by removal of the p lant and not by the fire. Nearly a decade after the fire, significant effects of A. tridentata on patterns of some soil variables in the bur ned site were still detectable. Significantly higher values for total organic C, total N, water soluble C, electrical conductivity, and soil microbial biomass C were observed near the location of charred A. tri dentata stumps than at distances further away. These patterns are a si gnificant source of soil variability that may be difficult to account for because they are not related to the obvious location of live plant s.