Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
Sci Total Environ. 2017 Mar 1;581-582:666-675. doi: 10.1016/j.scitotenv.2016.12.177. Epub 2017 Jan 6.
The impact of invasive species on native biodiversity varies across environments, with invasion effects of amphibious plant species across terrestrial and aquatic systems especially poorly understood. In this study, we established 29 terrestrial plots and 23 aquatic plots which were invaded by the alien plant alligator weed, Alternanthera philoxeroides in Southern China. We measured α-species diversity (Shannon-Wiener and Simpson index), species richness and evenness, species cover and the importance value (a comprehensive index of cover, height and abundance) of A. philoxeroides in invaded communities in both aquatic and terrestrial habitats. We recorded seven environmental factors (longitude, latitude, elevation above sea level, temperature, precipitation, ammonia and nitrate) across habitats. We then used Redundancy Analysis (RDA) to determine which factors best explain A. philoxeroides invasion in either environment type. We found that terrestrial habitats had greater species diversity (Shannon index) than aquatic habitats, and the biotic resistance of aquatic plant communities to the A. philoxeroides invasion was weaker than terrestrial plant communities. Accumulated ammonia improved some indices of species diversity (Shannon-Weiner, Simpson) and evenness, but decreased species cover of A. philoxeroides in both aquatic and terrestrial environments. Precipitation increased species richness in terrestrial habitats but decreased richness in aquatic habitats. Precipitation increased A. philoxeroides cover in both environment types, while elevated nitrate increased A. philoxeroides cover in terrestrial habitats only. In aquatic habitats, species richness increased but A. philoxeroides cover decreased with increasing longitude. Our study indicates that increased precipitation may accelerate A. philoxeroides spread across aquatic and terrestrial habitats, while reducing nitrate inputs could inhibit terrestrial A. philoxeroides invasion. Aquatic communities appear to be more vulnerable to invasion by A. philoxeroides than terrestrial communities, likely due to low native species diversity. We need to intensify invasion assessment of water ecosystems in lower longitudinal regions of China and elsewhere where diversity is low.
外来入侵物种对本地生物多样性的影响因环境而异，两栖植物物种在陆地和水生系统中的入侵效应尤其知之甚少。在这项研究中，我们在华南地区建立了 29 个陆地样地和 23 个水生样地，这些样地均被外来植物空心莲子草入侵。我们测量了入侵的空心莲子草在陆地和水生生境中的物种多样性（香农-威纳和辛普森指数）、物种丰富度和均匀度、物种盖度和重要值（涵盖度、高度和丰度的综合指数）。我们记录了跨越生境的七个环境因素（经度、纬度、海拔、温度、降水、氨和硝酸盐）。然后，我们使用冗余分析（RDA）来确定哪些因素最能解释两种环境类型中空心莲子草的入侵。我们发现，陆地生境的物种多样性（香农指数）大于水生生境，水生植物群落对空心莲子草入侵的生物抗性弱于陆地植物群落。累积氨改善了物种多样性（香农-威纳、辛普森）和均匀度的一些指数，但降低了空心莲子草在陆地和水生环境中的物种盖度。降水增加了陆地生境的物种丰富度，但降低了水生生境的物种丰富度。降水增加了空心莲子草在两种环境类型中的盖度，而升高的硝酸盐仅增加了空心莲子草在陆地生境中的盖度。在水生生境中，随着经度的增加，物种丰富度增加，但空心莲子草的盖度减少。我们的研究表明，增加的降水可能会加速空心莲子草在水陆生境中的传播，而减少硝酸盐的输入可能会抑制陆地空心莲子草的入侵。水生群落似乎比陆地群落更容易受到空心莲子草的入侵，这可能是由于本地物种多样性较低。我们需要加强对中国和其他低多样性地区水生态系统的入侵评估。
