Abstract: Plant allelopathy has been proven to affect ecological processes on different temporal and spatial scales (individual, population, community, ecosystem, regional, and global scales). Furthermore, allelopathy has been considered as a novel weapon against invading exotic species, and has become a hot topic in ecology in recent years. Many studies have focused on the separation, identification, release pathways, application potential, and functional mechanisms of allelopathic materials, and much progress has been made. However, the lack of a thorough clarification and summary of specific functional mechanisms of allelopathy has constrained our understanding of its ecological significance. In this paper, we summarize recent research progress and controversies about allelopathy and discuss its effects on ecological processes at different scales. We specifically focus on the grassland ecosystem, and discuss the ecological significance of allelopathy for ecological processes at different scales. We discuss the differences in, and connections between, allelopathy and interspecific competition, and explore the roles of allelopathy in community species composition, community succession, and biological invasion. We also discuss the functional mechanisms of allelopathy, and current research progress and methods used to study allelopathy in grassland ecosystems. Finally, we recommend the following topics for future research on allelopathy: 1) Comparisons among greenhouse, field, and laboratory studies on allelopathy; 2) the effects of allelopathy at regional or global levels; and 3) how allelopathy affects the defensive responses of herbaceous plants and the restoration of degraded grassland.

Key words: allelopathy, grassland ecosystem, ecological significance, allelopathic materials, functional mechanism