Plant nutrient availability following wildfire and different restoration practices in a sagebrush community in northwestern Utah

Background/Question/Methods Many post-fire restoration efforts fail for reasons unknown. One possibility is deficient plant nutrient availability in the soil. Vegetation establishment following fire is critical to restore soil structure, fertility, and biogeochemical processes. Ecosystem recovery of arid lands is dependent upon properly functioning soil-plant interactions; therefore, we investigated the effects of fire and two seeding treatments on soil physical and chemical properties and the resulting effects on vegetation in Great Basin big sagebrush (Artemisia tridentata Nutt.) communities. Two different rangeland seed drills (Kemmerer drill and Truax Rough Rider minimum-till drill) were used to plant a mixture of native shrubs, forbs, and grasses. Mixed-bed ion exchange resin bags were buried at ten centimeters depth in unburned, burned, and burned + drilled plots. In the burned plots, resin bags were placed in undisturbed soil; in the burned + drilled plots bags were placed in the drill's furrow and seed broadcast zones; bags in unburned plots were positioned under sagebrush canopy or in the interspace. Resin bags were in the soil for approximately four months during three periods (March-July, July-November, November-March). Resins were analyzed by inductively coupled plasma spectrometry to determine available Ca, Cu, Fe, K, Mg, Mn, Na, P, S, and Zn. Results/Conclusions Results showed no difference in available nutrients between drill types. In addition, there were no variations in nutrient availability between furrow and broadcast zones. Both Cu and Na had higher levels in the summer than in the spring across all treatments and were higher during summer in burned plots compared to unburned plots. Fe, Mn, and Zn availability was higher in the spring than the summer across all treatments. During the spring period, K had higher levels than in the summer and was higher in unburned plots under the sagebrush canopies. No apparent trends were seen with Ca, S, and Mg. Whereas different drill types or seed zones did not change availability, uptake by plants, soil moisture and heterogeneity, and seasonality may have affected the levels of available nutrients in both the unburned and burned locations. Wildfire and restoration practices may influence other soil parameters; however, variable nutrient levels throughout the site indicate that they do not drastically reduce overall nutrient availability to plants.