Stand biomass decreases towards the edge of a range expanding invasive plant, Mikania micrantha, but only on thick soil layers

During range expansion, invasive plants may evolve distinctive traits that make them rapidly occupy the suitable sites at the invasion front, but it is unknown how stand biomass (i.e., biomass production of dense monocultural stands, which may predict invasion speed and impacts) changes during range expansion, and if stand biomass is related to competitive ability. In this study, we examined how competitive ability against common intraspecific competitors and stand biomass when six plants from the same population were grown together change during range expansion, using 27 populations of the invasive Mikania micrantha on Hainan island of China. Competitive ability did not decrease towards the range edge. Stand biomass decreased towards the range edge in 11 L pots with a thick soil layer, but not in 3 L pots with a thin soil layer. Stand biomass was negatively correlated with root-to-shoot ratio in 3 L pots but not in 11 L pots. Stand biomass was unrelated to competitive ability. Our resu..., ,在入侵范围扩张过程中，入侵植物可能演化出独特性状，使其能够快速占据入侵前沿的适宜生境，但目前尚不明确林分生物量（stand biomass，即高密度单优群落的生物量产出，该指标可用于预测入侵速度与生态影响）在范围扩张过程中的变化规律，以及林分生物量是否与竞争能力存在关联。本研究以中国海南岛的27个入侵植物薇甘菊（Mikania micrantha）种群为研究材料，探究当同一种群的6株植物共同种植时，其对常见种内竞争者的竞争能力以及林分生物量如何随入侵范围扩张发生改变。竞争能力并未随分布范围边缘的推移出现下降趋势。在土层较厚的11升种植盆中，林分生物量随分布范围边缘推移呈下降趋势，但在土层较薄的3升种植盆中未出现该变化。在3升种植盆中，林分生物量与根冠比（root-to-shoot ratio）呈负相关关系，但在11升种植盆中未观察到该相关性。林分生物量与竞争能力无显著关联。本研究结果……