Data from: The importance of factors controlling species abundance and distribution varies in native and non-native species.

How variation in factors controlling species abundance and distribution between native and non-native ranges compares to that within ranges remains poorly understood. We used a globally distributed ruderal, Centaurea solstitialis (Centaurea), to explore the possibility that the importance of those factors exhibits great variation between and within ranges. To test our hypothesis, we established seed addition experiments with soil disturbance (turnover and control) and biocide (fungicides, insecticide, and control) treatments in two regions within native (the Caucasus and south-western Turkey) and non-native (the western United States – US – and central Argentina) distributions. Also, we estimated the rate of vegetation recovery after disturbance (resilience) and related it to Centaurea density in experimental plots. Disturbance strongly increased Centaurea density in all regions. Density was similar between the native Caucasus and non-native Argentina and much greater in those regions than in the native Turkey and non-native US in biocide-free plots. Fungicides had positive effects on density in the US and negative ones in the Caucasus and Argentina, resulting in no differences between those three regions and greater density in the US than Turkey. Insecticide applications promoted Centaurea density in Turkey and Argentina, but inter-regional comparisons of density in treated plots were comparable to those in biocide-free plots. Overall, plants were smaller and less fecund in Turkey than the other regions, except the US. The greatest fungal attack was documented in Turkey, and herbivory was stronger there and in Argentina than in the Caucasus and US. The resilience of the local community explained a large proportion of variation in Centaurea density. These results support our hypothesis, and reveal that the speed at which competition is re-gained after disturbance may influence global variation in Centaurea abundance. Because many ruderals exhibit native and non-native distributions, our results are likely to be generalized to other systems.

关于调控物种丰度与分布的各类因子，其在本土分布区与外来分布区间的差异相较于单一分布区内的差异这一科学问题，迄今尚未得到充分阐释。本研究以全球广布的伴人杂草（ruderal）黄星蓟（Centaurea solstitialis，简称Centaurea）为研究对象，旨在探究上述调控因子的重要性在分布区间及分布区内均存在显著差异这一假说。为验证该假说，我们在矢车菊的两个本土分布区（高加索地区与土耳其西南部）及两个外来分布区（美国西部——简称US——与阿根廷中部）内，设置了包含土壤扰动（翻耕处理与对照组）及生物杀灭剂（杀菌剂、杀虫剂与对照组）的种子添加实验。此外，我们还估算了扰动后植被的群落恢复力（resilience），并将其与实验样地内矢车菊的种群密度进行关联分析。土壤扰动在所有研究区域均显著提升了矢车菊的种群密度。在无生物杀灭剂处理的样地中，本土高加索地区与外来阿根廷地区的矢车菊密度相近，且二者均显著高于本土土耳其地区与外来美国西部地区。杀菌剂处理在美国地区对矢车菊密度具有正向影响，而在高加索与阿根廷地区则产生负向影响，这使得上述三个区域的矢车菊密度无显著差异，且美国地区的密度显著高于土耳其地区。杀虫剂处理在土耳其与阿根廷地区提升了矢车菊密度，但处理样地间的区域密度差异与无生物杀灭剂处理样地的差异基本一致。整体而言，除美国地区外，土耳其地区的矢车菊植株个体更小、繁殖力更低。土耳其地区的真菌侵染程度最高，且该区域与阿根廷地区的植食性取食强度均高于高加索与美国地区。本地群落的恢复力可解释矢车菊种群密度变异的绝大部分。上述研究结果验证了本研究的假说，并揭示出扰动后群落竞争能力的恢复速率，可能是影响矢车菊全球丰度差异的关键因素。鉴于众多伴人杂草均存在本土与外来分布格局，本研究结果有望推广至其他同类研究系统。