Positive effects of biomass of unpalatable neighborhoods on palatable plants in a grassland community under heavy grazing pressure by sika deer

The intensity of grazing on palatable species can vary depending on the neighboring plants in plant communities. We aimed to search for species whose biomass can have a positive effect on palatable plants near them in a grassland under grazing pressure by sika deer. We selected Iris sanguinea Hornem. as an indicator species of ease of being grazed because it is a palatable and past dominant species before the increase in deer density. We estimated the effects of the biomass of neighboring plant species, soil water content, and distance from the forest edge on the height of I. sanguinea. The height was remarkably and positively affected by the biomass of four graminoid species with larger biomass and slightly positively affected by the biomass of a toxic species. This study suggests that the biomass of less-palatable species may have an important influence on the size of palatable species under grazing pressure by deer.