arbuscular mycorrhizal fungi microscopy next-generation sequencing Arbuscular mycorrhizal fungi Caloplaca Caloplaca substerilis subsp. orbicularis Glomeromycota Listera Neottia camtschatea Neottia cordata Neottia ovata Neottieae Orchidaceae Rhizoctonia Rhizophagus irregularis Sebacinales Tulasnellaceae Xanthorioideae cultivation bias diversity field experiment forbs functional traits germination grasses mixotrophy next generation sequencing (NGS) non-mycorrhizal plants nutrient availability nutrient foraging orchid mycorrhiza