Field establishment of fourwing saltbush in processed oil shale and disturbed native soil as influenced by vesicular-arbuscular mycorrhizae

Seedlings of fourwing saltbush ( Atriplex canescens (Pursh) Nutt.) were inoculated with indigenous vesicular-arbuscular mycorrhizal (VAM) fungi in a containerized system and transplanted into processed oil shale and disturbed native soil in a semiarid rangeland environment in northwestern Colorado. After two growing seasons in the field, plants inoculated with VAM had greater aboveground biomass, cover, and height than noninoculated plants. Mycorrhizal plants were more effective in the uptake of water and phosphorus. Infection levels of inoculated plants were greatly reduced in processed shale (from 13.0 at outplanting to 3.8 at harvest), but functional VAM associations could be found after two growing seasons. Results indicate that VAM help make processed oil shale a more tractable medium for the establishment of plants representative of later successional stages by allowing these plants to make effective use of the natural resources that are limiting under conditions of high stress.