Can mine reclamation with an exotic grass species precede successful restoration in intermountain grasslands? A case study with Agropyron cristatum.

We performed four experiments to test whether or not native plants germinated with physical and chemical contact with crested wheatgrass (Agropyron cristatum (L.) Gaertn.), a grass species native to Eurasia which has been widely used for mine reclamation in North America. In our study area Butte, Montana, A. cristatum was planted on capped mine waste and, in many cases, has formed a monoculture with a large buildup of leaf litter. We found there to be a much higher mean litter depth on these lands when compared to wild grasslands. Leaf litter proved to be a significant barrier for the establishment of native plant species via natural process or restoration attempts. We performed four experiments to begin to build evidence that A. cristatum may not only constitute a physical barrier for natives via the excessive buildup of leaf litter but also exhibiting allelopathic traits. Our results showed strong evidence that A. cristatum is a severe limiting factor for the establishment of desired native species in our study area by creating a dense physical and/ or chemical barrier. Based on our findings, we conclude the continued use of A. cristatum as a reclamation species in our study area is not advised.