DEMONSTRATION STUDY: CONSERVING AN S1/G5/T2 MUSTARD AT A SOUTHCENTRAL MONTANA COAL MINE THROUGH NURSERY PROPAGATION AND TRANSPLANTING

Abstract

99 DEMONSTRATION STUDY: CONSERVING AN S1/G5/T2 MUSTARD AT A SOUTHCENTRAL MONTANA COAL MINE THROUGH NURSERY PROPAGATION AND TRANSPLANTING G. L. Johnson and R. A. Prodgers Abstract. Protected rare plants can hinder mine development if not conserved. Spring Creek Coal Mine (SCCM) in southcentral Montana adopted a proactive conservation/propagation program for an uncommon but not formally protected variety of perennial mustard found in a topsoil-stripping area. The objective is to reestablish a self-sustaining population of Physaria didymocarpa (Hook.) A. Gray var. lanata A. Nelson, woolly twinpod, in reclamation and elsewhere within the permit area. This recognized variety is rated S1 in Montana (at risk, imperiled); the G5 (common, secure) global designation refers to generic Physaria didymocarpa (common twinpod), whereas T2 (less imperiled than S1, it occurs also in WY) refers to the trinomial (var. lanata). In the wild, fruits aren’t produced every year and empty capsules are common, hence prospects for collecting seed appeared dim. Fifty mature plants were collected from the nexus of the population, transplanted, and used for tissue culturing (cloning) and later for seed collection. Between 500 and 1,000 plants annually were transplanted into the mine permit area beginning in fall 2008. In addition to the problems inherent to a stenotopic functional annual of very limited competitive ability, these limitations have manifested in the transplant program: • Windblown dust accumulation in the foliage inhibited plant survival. The epithet “lanate” refers to long, tangled, woolly hairs. • The fresh scoria into which transplants were planted in a few months became a dense sward of 5 dm tall kochia (Bassia scoparia) with a scattered twinpod understory. Kochia was more successful in capturing water, nutrients, and light. • Disturbed or placed scoria subsequently becomes a magnet for yellow sweetclover (Melilotus officinalis), a tall nitrogen-fixing legume and copious seeder that overtopped and apparently competed with twinpod, the growth and survival of which did not appear to be assisted by increased mineral N, if present. • Herbivory from ungulates and insects. Spring transplanting is now performed into both mined and unmined areas. While transplants survive, a self-sustaining population is not yet assured. Further transplanting and adaptive practices continue at the mine. These lessons may guide others similarly engaged.