Long-Term Reestablishment of Arbuscular Mycorrhizal Fungi in a Drastically Disturbed Semiarid Surface Mine Soil

Abstract

Reestablishment of arbuscular mycorrhizal (AM) fungi in severely disturbed soil on a surface mine reclamation site inoculated with native endophytes in 1983 was examined in 1997. At that earlier time (1983) research had been initiated on a newly reclaimed site to test the hypothesis that native AM fungi would form effec tive mycorrhizae and would improve growth of W yoming big sagebrush (Artemisia tridentata ssp. wyomingensis) in severely disturbed reclamation soil. Data collected during 1984 and 1985 did not support that hypothesis and it was concluded that native AM fungi inoculated onto the site were not tolerant of the altered soil environmental conditions in the reclamation soil. Reexamination of the site in 1997 indicated that soil environmental conditions were becoming more similar to those before disturbance and AM fungal populations were recovering. Soil analyses in 1997 show an approximate 1 % increase in soil organic matter content, improvement in soil structure compared to 1983, and decreases in amounts of soluble salts and Na. Mycorrhizal inoculum potential of the disturbed soil and levels of mycorrhizae formation on sagebrush roots on the site were much greater in 1997 than in 1985. Also, AM fungal spore density in 1997 was not significantly different in reclamation soil than in adjacent undisturbed native soil. These observations were interpreted as evidence that populations of AM fungi on the site are recovering and becoming more active as soil environmental conditions ameliorate.