The Litter Decomposition Characterization Of An Invasive Plant Flaveria Bidentis And Its Effect On Plant Inter-Competition

An exotic plant Flaveria bidentis, which invaded in many areas in China with serious damage, has become a kind of malignant invasive plant due to its very powerful ability to reproduce and survival ability. Litter is an important part of ecological system, connecting to the ground in the middle of the transition layer. as one of exotic harmful plants, little is known on F. bidentis its effect on litter decomposition rate and nutrient release in invaded systems and its role in mediate interplant competition. In order to answer this question, We conducted a 1-year litterbag experiment using leaf litters from the invasive species, F. bidentis, and the dominant co-occurring native species, Setaria viridis, that were decomposed either separately or together in different mixing ratios in a mothproof screen house.At same time, we conducted a test to examine the combined effects of competition and plant litter from conspecific versus heterospecific species on the emergence and early growth of invasive F. bidentis and co-occurring seedlings of native Amaranthus retroflexus. Understanding the responses of native versus non-native species to conspecific versus heterospecific litters in the presence of competitors may provide more in-depth insight into the relationships between litter accumulation and plant diversity, and give us a more complete understanding of litter-mediated mechanisms in a restoration context. The main results are as follows:The mass loss of all litter mixtures was non-additive, and the direction and strength of effects varied depending mixing ratios and decomposition stages. During the initial stages of decomposition, all mixtures had a neutral mixing effect on the mass loss; however, at later stages of decomposition, mixtures containing more invasive litter had synergistic mixing effects. Importantly, with the increase of F. bidentis litter, the mixture had antagonistic to synergistic mixing effects on the release of N, and litter having lower C:N tended to lead to more synergistic N loss over time. These results highlighted the importance of chemical heterogeneity in determining decomposition rates of litter mixtures and suggested that F. bidentis could further synchronize N release from the litters as invasion proceeds, thus potentially enhancing positive litter feedback to invasion. Even so, there might be a substantial lag time between initial introduction of invasive plant species and subsequent nutrient cycling change.Our results showed that seedling emergence of F. bidentis was negatively affected by the presence of native litters, and this effect was stronger in combination with native competitor. Both interspecific competition and litter affect the seedling early growth of F. bidentis at same time. While litter addition reduced only seedling emergence of A. retroflexus, they have from neutral to positive effect the growth of A. retroflexus, indicating a clear species-specific pattern. Litter addition, combined with competition, even facilitate growth of A. retroflexus which seem to be better adapted to soil changing conditions than F. bidentis. Consequently, a habitat-specific adaptation might be involved in inter-specific plant-soil feedback. This has implications for the ecological management of F. bidentis on disturbed sites, using strategies such as manipulation of litter cover through the physical impact of dense native leaf litter, combined with their allelopathic effect on seedling growth and with native competition to assist in native rehabilitation.