Poster #14

The relationship between population density of invasive plants and soil microbial communities

N. NAKAMURA, S. LUKE FLORY, H. TOJU, K. KADOWAKI, K. KITAJIMA
Graduate School of Agriculture, Kyoto University, Kyoto, Japan

The invasion process by exotic plants progresses through advancing degrees of invasion, from uninvaded to monodominant. However, how interactions between invasive plants and soil properties change with their local density remains largely unexplored. Here, we investigated the diversity and structure of soil fungal and procaryotic communities, as well as soil chemical characteristics, in relation to the local density of an invasive plant Ardisia crenata. The level of invasion was quantified as the local density within 1-m2 circular plots, i.e., high-density, low-density and uninvaded plots. For each level, we designated twenty-five 1m2 plots for collecting soil samples. The results showed that light levels (low-density) of invasion by A. crenata did not alter the soil biotic and abiotic properties compared to uninvaded area. In contrast, where monodominance of A. crenata had been established, there was a marked changes in soil chemistry (e.g., pH, soil organic matter) and notable shifts in microbial community diversity and structure. This suggests that the local density of invasive plants above a certain threshold plays a significant role in the alteration of biotic and abiotic soil environmental factors, and these changes may further modify the invasion process.