加拿大一枝黄花入侵对本土植物群落动态的影响及其机制

了解外来植物入侵对本土植物群落种群动态的影响对于植物入侵的防控极为重要。该文以加拿大一枝黄花(Solidago canadensis)入侵不同阶段的植物群落为研究对象, 对本土植物物种多样性以及常见优势种群的生态位变化进行了定量分析。结果表明: 加拿大一枝黄花氮素积累能力高于其他本土优势种群。随着加拿大一枝黄花入侵的深入, 本土植物群落的物种多样性呈现显著下降趋势; 氮素积累能力高的本土优势种群生态位宽度呈现明显的上升趋势, 而氮素积累能力低的本土优势种群生态位宽度则呈现明显下降的趋势; 本土优势种群的生态位重叠平均值呈现逐步下降的趋势。加拿大一枝黄花的入侵, 显著提高了土壤硝态氮含量, 而土壤铵态氮、有效磷、全磷和全氮含量显著降低。对氮素的积累能力决定了加拿大一枝黄花入侵后, 本土植物种群的动态变化格局。

Effects of Solidago canadensis invasion on dynamics of native plant communities and their mechanisms

Aims Understanding the impacts of invasive plants on the dynamics of native plants in invaded communities is important for the control of the invasives. Our objectives were to analyze the dynamics of native plants in communities invaded by Solidago canadensis.
Methods We selected native plant communities that had experienced different densities of S. canadensis invasion. Four different invasive stages (based on S. canadensis densities of 0, 5–7, 11–13 and >18 ind. plant·m^–2) were determined, and 10 plots were randomly distributed in each invasive stage. The plant height, density and aboveground biomass of native species in each plot were measured. The niche breadths and niche overlap coefficients of seven common native species were determined for each plot. Nitrate nitrogen (N), ammonia N, available phosphorus (P), total P and total N of soil were measured, as was total N of plant tissue for the seven common native species.
Important findings Solidago canadensis had more N accumulation than all seven common native species. The invasion of S. canadensis significantly decreased native species richness. With greater intensification of S. canadensis invasion, niche breadth significantly increased for native species with higher plant tissue total N but significantly decreased for native species with lower plant tissue total N, and the average value of niche overlap coefficients of each native species decreased. The invasion of S. canadensis significantly increased soil nitrate N, but decreased soil ammonia N, available P, total P and total N. Results indicated that the ability to accumulate nitrogen determined the dynamics of native plant species when communities were invaded by S. canadensis.