An evaluation of planting sites and mycorrhizal amendments for successful establishment of American Chestnut (Castanea dentata) in mine reclamation

The American Chestnut Foundation’s backcross breeding program has resulted in blight resistance progeny that contain ~94% American chestnut genes.  With these hybrids now available, more information is required for the selection of field conditions most conducive for re-introduction.  To evaluate germination and survival, seeds were sown in three abandoned strip mines in Eastern Ohio.  Three locations within the mines were assessed: plots parallel to an existing 40-year-old forest edge, center of the mine (devoid of vegetation), and adjacent to 10-year-old Virginia pines inoculated with Pisolithus tinctorius (Pt).  Germination percentages were higher within subplots adjacent to the Pt inoculated Virginia pines (48%) when compared to center plots (26%) and forest edge (21%).  In addition, subplots adjacent to Pt inoculated Virginia pines exhibited a healthier, more vigorous growth habit with less mortality.  The second objective of this study compared seedling establishment between seeds that were sown with commercial Pt inoculum to seeds sown without.  Seedlings were similar in height and leaf production regardless of inoculation status. Thirty-six seedlings representing all treatments were sampled and molecular techniques were used to identify the fungi found colonizing roots.  Of the 36 sampled, 17 were ectomycorrhizal; 9 of them were from plots that were not treated with commercial inoculum.  Interestingly, all ectomycorrhizal species found on roots were not part of the inoculum we introduced.  This indicates that there are native populations of ectomycorrhizae present in these mine soils capable of infecting chestnut roots.  Future work will determine if these native fungi enhance seedling growth and survival.