Facilitation by Baccharis sarothroides (desert broom) during revegetation of a hard rock mine in Southern Arizona, USA

Abstract

Post mining revegetation efforts are often faced with challenges associated with poor soil conditions and sparse vegetation. Revegetation in arid regions faces further challenges due to scant and infrequent rainfall during the initial phases of plant establishment. Early successional plants may provide utility for targeted management to enhance remediation outcomes as these species have high dispersal capabilities and rapid growth rates, enabling them to successfully dominate landscapes very quickly after degradation. This research aims to test whether the native Baccharis sarothroides Gray (desert broom), a common early successional species, facilitates the growth of native plant communities on a copper mine in Southern Arizona. Fifty B. sarothroides individuals of varying sizes were randomly selected on a mine tailings waste pile and the plant communities growing both under their canopies as well as in exposed areas were characterized. Soil chemical composition and abiotic conditions were also assessed. We found higher plant density, cover, diversity, and species richness under B. sarothroides canopies in comparison to the exposed areas, however, the height of the individual had no effect. Baccharis sarothroides provides some alleviation from abiotic stresses by creating a cooler understory with higher soil moisture levels and lower soil temperature. Baccharis sarothroides demonstrates value for increasing revegetation success on copper mine tailings storage facilities.