英文题目：Plant height and leaf size: Which one is more important in affecting the successful invasion of Solidago canadensis and Conyza canadensis in urban ecosystems?
全文链接：https://doi.org/10.1016/j.ufug.2021.127033
英文摘要：It is still debated whether invasive alien species (IAS) have superior functional traits, especially plant height and leaf size, than co-occurring native plant species (NPS). Meanwhile, as two important indicators affecting the competitiveness for sunlight acquisition, plant height and leaf size, which one is more important in affecting the successful invasion of IAS? Thus, it is vital to assess the differences in the functional trait between IAS and co-occurring NPS and the significance of plant height and leaf size in the successful invasion to further elucidate the mechanisms underlying successful invasion especially with diverse degrees of invasion, especially in urban ecosystems. This study aims to assess the differences in the functional trait between IAS and co-occurring NPS and the significance of plant height and leaf size in the successful invasion of two notorious IAS [i.e., Solidago canadensis L. and Conyza canadensis (L.) Cronq.] with different degrees of invasion (i.e., low and heavy degrees of invasion based on their relative abundance in the invaded habitats) in urban ecosystems by using field sampling experiments. The competitiveness for sunlight acquisition of IAS distinctly increases as the degree of invasion increases. The competitiveness for sunlight acquisition of IAS is evidently higher than that of NPS but contrary to the leaf photosynthetic area. Plant height is more strongly related to the relative abundance of the two IAS than leaf size. The contribution intensity of plant height of the two IAS to their relative abundance is obviously higher than leaf size. Thus, plant height, rather than leaf size, was the most important determinant of the successful invasion of the two IAS, especially under heavy degree of invasion. Thus, the invasiveness of the two IAS is largely contributed by the higher competitiveness for sunlight acquisition rather than the larger leaf photosynthetic area, especially under heavy degree of invasion.
科学问题：
1. 入侵植物的株高和叶片大小哪一个对其入侵竞争力的贡献度较大?
2. 株高和叶片大小对入侵植物加拿大一枝黄花的入侵竞争力贡献度大还是对入侵植物小飞蓬的入侵竞争力贡献度大?
3. 入侵植物的株高和叶片大小对其入侵竞争力贡献度是否存在入侵程度依赖性? 入侵植物的株高和叶片大小对其入侵竞争力贡献度是随入侵植物入侵程度的增加而增加还是随入侵植物入侵程度的增加而减弱?
设计思路：
1. 入侵植物选择：选择两种菊科入侵植物，即：加拿大一枝黄花(Solidago canadensis L.)和小飞蓬(Conyza canadensis (L.) Cronq.; 也称作加拿大蓬或小蓬草)。
选择主要原因如下：(1)这两种入侵植物常在同一生态系统形成共同入侵(如苏南地区)。(2)这两种入侵植物均已在中国大部分地区造成显著的生态影响(特别是长江中下游地区)。(3)这两种入侵植物均已先后被国家生态环境部列入中国外来入侵物种名单(加拿大一枝黄花, Ministry of Environmental Protection of the People’s Republic of China. 2010. The Second Batch of Alien Invasive Plants in China. pp. 7.; 小飞蓬, Ministry of Environmental Protection of the People’s Republic of China & Chinese Academy of Sciences. 2014. The Third Batch of Alien Invasive Plants in China. pp. 7.)。(4)这两种入侵植物均起源于美洲[以尽量减少植物地理区系起源所致的差异，且中国入侵植物在起源地方面原产于美洲的种类较多(引入频次高达137，约占入侵植物总引入频次的21.47%；Yan et al. 2014)]；(5)这两种入侵植物均隶属于菊科[以尽量减少植物亲缘关系所致的差异，且在物种组成方面中国入侵植物隶属于菊科的种类最多(物种数高达92种，约占入侵植物总物种数的17.86%；Yan et al. 2014)]；(6)这两种入侵植物具有类似的入侵生境(以农田、荒地、道路两侧、林地边缘、草地、部分公园和风景区等为主)、生活型(均为草本，且株高基本处于同一水平)和生长周期(在苏南地区两者的生长周期约为3月至11月，其中生长旺盛期约为5月至9月)。
2. 采样区域选定：中国华东地区、华中地区、华北地区的四省十市，以尽可能降低由于不同采样区域所致入侵植物生长情况存在明显之差异所造成的误差。
3. 入侵程度划分：入侵植物的入侵程度根据其相对丰度(入侵植物的相对丰度为调查样方内入侵植物的植株数量与调查样方内所有植物的植株数量总数之比值)划分为：低度入侵(0~50%, low degree of invasion)和重度入侵(50%~100%, heavy degree of invasion)。其中加拿大一枝黄花每一入侵程度各测定72个样方(2 m × 2 m)，而小飞蓬每一入侵程度各测定136个样方(2 m × 2 m)，共计416个样方(2 m × 2 m)。
