Multiple biotic factors mediate the invasion success of Chromolaena odorata

Abstract

Community resistance plays a crucial role in the successful invasion of alien plants. However, our understanding of how soil legacy effects of native species richness, parasitic plants, competition and soil microbes contribute to community resistance remain unclear. To compare the legacy effects of soil conditioning and the current effects of plant interactions, we performed an experiment in which Chromolaeana odorata (invader) growth was measured with or without competition on live and sterile soils with different conditioning histories (species richness). Overall, our research indicated that C. odorata outperformed two native species across treatments, however, this advantage was smaller on soils with species rich histories and with competition from current plant growth. Our findings also revealed that both the soil legacy effects of native richness and competition negatively impact the growth of C. odorata, and native plants tend to produce more biomass in soils with greater diversity and under competitive conditions (5.0%). Interestingly, the holoparasitic plant C. chinensis decreased native plant growth (− 40%) more than C. odorata growth (− 11%). Further, C. chinensis did not parasitize C. odorata on sterilized soil. Furthermore, C. odorata did not experience limitations from parasitism in sterilized soil, as indicated by a slight increase in biomass of 2.3%. These results indicated that soils with diverse plant histories, competition from native plants, and lower C. chinensis parasitism will synergistically decrease C. odorata invasion. This study underscores that community resistance to C. odorata is governed by an interplay of multiple biotic factors, both individually and in combination. Simultaneously, this study contributes to a theoretical foundation for understanding the successful invasion of alien plants.