The objective of this research was to evaluate planting protocols that may aid in seedling establishment on reclaimed coal mines in central Ohio by encouraging root colonization from ectomycorrhizal (ECM) fungi. Two field studies used American chestnut (Castanea dentata) and blight resistant hybrid chestnut (C.dentata x C. mollissima) to evaluate: 1) the effects of mechanical soil treatments on native ectomycorrhizal (ECM) fungi, and 2) the persistence and movement of introduced ECM inoculum. The first study sampled roots from seedlings planted in either plots that were cross-ripped, plowed and disked, or a combination of both treatments. Plant height and basal diameter were recorded and related to ECM colonization. The presence of native ECM was sequenced to determine fungal species identity. In the second study, 1 year-old chestnut seedlings previously inoculated with one of five different species of ECM fungi (Hebeloma crustuliniforme, Laccaria bicolor, Amanita rubescens, Suillus luteus, and Scleroderma cepa) were planted. A combination of BLAST searches and phylogenetic analyses were used to identify ECM fungi to confirm the persistence of the inoculating strain. To test the ability of the fungal inoculum to colonize incoming seedlings, chestnuts planted as seeds 30 cm from the inoculated seedling were also sampled.
Results/Conclusions:
Study 1: Mechanical soil treatments resulted in seedlings with significantly more ECM root tips and species richness when compared to the control plots (P = 0.0001 and 0.01, respectively). There were significant interactions between soil treatments and native ECM infection when comparing seedling height (P = 0.008) and basal diameter (P = 0.03). Chestnut seedlings found naturally colonized by ECM fungi had the greatest shoot production in the mechanically treated plots when compared to their non-ECM counterparts. Employing methods of surface conditioning that alleviate soil compaction while encouraging native ECM colonization aid in chestnut establishment on reclaimed mines. Study 2: After one growing season, chestnuts inoculated with ECM had significantly higher survival (71-88%) than the non-inoculated control plants (24%) (P = 0.001). When growth measurements were compared, ECM inoculated plants were taller with a greater leaf area (P = 0.001 and 0.003). There was one exception, seedlings inoculated with A. rubescens performed similarly to the non-inoculated control plants. However, after two field seasons, S. sepa was the only inoculum that persisted on chestnut. This Scleroderma species was also sampled from the trap trees indicating both persistence and movement of this species in mine reclamation projects using chestnut.
