Fine-scale clonal structure of the lingonberry Vaccinium vitis-idaea under the nurse plant Pinus pumila vegetation in alpine region, Mt. Norikura.

Abstract

Abstract Nursery effect is a positive interaction wherein a nurse plant improves the abiotic environment for another species (beneficiary plant) and facilitates its establishment. The evergreen shrub Vaccinium vitis-idaea (beneficiary plant) grows mainly under the dwarf shrub Pinus pumila (nurse plant) in the alpine regions of central Japan. However, whether V. vitis-idaea shrubs under various P. pumila shrubs spread through clonal growth and/or seeds remains unclear. Here, we aimed to investigate the clonal structure of V. vitis-idaea under the nurse plant, P. pumila, in Japanese alpine regions. MIG-seq analysis was conducted to compare isolated and patchy P. pumila plots on the ridge (PATs) and plots covered by dense P. pumila on the slope (MAT) on Mt. Norikura, Japan. We detected 15 and 17 multi-locus genotypes in 209 ramets across 11 PATs and 130 ramets in one MAT, respectively. Approximately half of the PATs consisted of a single genet. These results suggest that the seeds of V. vitis-idaea were dispersed under small P. pumila patchy shrubs and spread by clonal growth in small PATs. The genet abundance curve of MAT was more moderate than that of PATs, and the clonal diversity of MAT was lower than that of PATs on a small scale. Therefore, spatial spread of the nurse plant P. pumila facilitates germination via the seeds of V. vitis-idaea. Our results show that the nursery effect on the genetic diversity of beneficiary plant increased positively with the spatial size of nurse plants in alpine regions, leading the sustainability of the beneficiary populations.