Institute of Wetland Ecology & Clone Ecology/Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou 318000, China; School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, China.
Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
Sci Total Environ. 2020 Nov 25;745:141056. doi: 10.1016/j.scitotenv.2020.141056. Epub 2020 Jul 20.
Clonal plants can make up a disproportionately high number of the introduced, invasive plant species in a region. Physiological integration of connected ramets within clones is a key ecological advantage of clonal growth. To ask whether clonal integration underlies the invasiveness of clonal plants, we tested the hypothesis that introduced clones of an invasive species will show higher capacity for integration than native clones of the same species. We conduct a greenhouse experiment on the widespread, perennial herb Hydrocotyle vulgaris. Clonal fragments consisting of pairs of connected ramets from seven sites in northwestern Spain where the species is native and seven sites in southeastern China where the species is introduced and invasive were grown for 79 days with the younger, apical ramet shaded to 30% of ambient light and the connection between ramets either severed or left intact. Severance decreased the final dry mass and ramet number of the apical ramet and its offspring in nearly all clones and increased the mass or ramet number of the basal portion of the fragment in about half of the clones, but these effects did not differ consistently between native and introduced clones. Severance did affect allocation more in introduced than in native clones, decreasing root/total mass more in apical portions and increasing it more in basal portions. Maintaining the connection between ramets caused introduced, but not native, clonal fragments to produce more leaf and less root mass and thus to lower allocation to roots. Regardless of severance, introduced clones accumulated about twice as much mass as native clones. Results suggest that introduced clones of a species can show greater effects of integration on allocation than native clones. In species such as H. vulgaris, this might increase competitiveness for light.
克隆植物在一个地区的引入、入侵植物物种中可能占不成比例的高数量。连接的分株在克隆内的生理整合是克隆生长的一个关键生态优势。为了探究克隆整合是否是克隆植物入侵的基础，我们检验了以下假设：入侵物种的引入克隆将比同一物种的本地克隆具有更高的整合能力。我们在广泛分布的多年生草本植物Hydrocotyle vulgaris 上进行了温室实验。克隆片段由来自西班牙西北部的七个原生地点和中国东南部的七个引入和入侵地点的成对连接分株组成。在 79 天的时间里，对年轻的、顶端分株进行遮荫，使其受到环境光的 30%，并将分株之间的连接切断或保持完整。切断连接几乎降低了所有克隆中顶端分株及其后代的最终干质量和分株数量，并增加了片段基部的质量或分株数量，大约一半的克隆，但这些影响在本地和引入克隆之间并不一致。切断连接确实对引入克隆的分配影响更大，在顶端部分降低根/总质量更多，在基部增加更多。保持分株之间的连接导致引入的，但不是本地的，克隆片段产生更多的叶和更少的根质量，从而降低根的分配。无论是否切断连接，引入的克隆积累的质量大约是本地克隆的两倍。结果表明，与本地克隆相比，物种的引入克隆可能表现出更大的整合对分配的影响。在像 H. vulgaris 这样的物种中，这可能会增加对光的竞争力。
