The distribution and impact of an invasive plant species (Senecio inaequidens) on a dune building engineer (Calamagrostis arenaria)

These data sets are used to run the analyses in the paper '<em>The distribution and impact of an invasive plant species (</em>Senecio inaequidens<em>) on a dune building engineer (</em>Calamagrostis arenaria<em>)</em>' by Van De Walle et al., 2022, Neobiota (in progress). The presence/absence data (PA) of <em>Senecio inaequidens</em> in European coastal dunes can be found in 'Senecio_PA.xlsx', in the tab 'senecio_PA', together with the country and location where the occurrences were mapped. The spatial parameters (proportion = P and Join counts = H) for all different scales (5, 10, 20 and 50m) are included as well as a combination of letter and scale (i.e. P_5 = proportion of marram grass cover in a 5m circle). All coordinates of the samples are available in the tab 'coordinates samples'. 'Marram_growth_experiment.xlsx' contains the data gathered during the growth experiment. The origin of the sand is subdivided in 3 columns: 'Location' represents the location along the Belgian coast where sand was gathered, 'senecio' represents whether sand was gathered from underneath a senecio plant (='bkk', short for BezemKruisKruid, Dutch name for <em>S. inaequidens</em>) or not (=sand) and 'biota' represents whether biota could affect marram grass growth (biota = 0 thus means that the sand was sterilized). 'numb_leaves' = number of leaves, 'length_leaves_end' &amp; 'length_roots_end' = length of the longest leave and root, 'leaves_fresh_end' &amp; 'roots_fresh_end' = weight (in g) of the fresh leaves and roots, 'leaves_dry_end' &amp; 'roots_dry_end' = dry weight (in g) of leaves and roots. All these measures were taken at the end of the experiment. <strong>Abstract</strong> Disturbance is thought to enhance the probability of invasive species establishment, a prerequisite for naturalization. Coastal dunes are characterized by disturbance in the form of sand dynamics. We studied the effect of this disturbance on the establishment and spread of an invasive plant species (<em>Senecio inaequidens</em>) in European coastal dunes. Local sand dynamics dictate the spatial configuration of marram grass (<em>Calamagrostis arenaria</em>). Therefore, marram grass configuration was used as a reliable proxy for disturbance. As marram grass plays a crucial role in natural dune formation, we evaluated the possible effects <em>S. inaequidens</em> could have on this process, if it would be able to naturalize in European coastal dunes. We expected the highest probability of <em>S. inaequidens </em>establishment at intermediate marram grass cover because too low cover would increase sand burial, whereas high cover would increase competition. However, our results indicate that <em>S. inaequidens</em> is quite capable of handling higher levels of sand burial. Thus, probability of <em>S. inaequidens</em> establishment was high under low marram cover but slightly lowered when marram cover was high, hinting at the importance of competition. We expected a negative impact of <em>Senecio</em>-altered soils on marram grass growth mediated by soil biota. However, marram grass grew better in sand gathered underneath <em>Senecio</em> plants due to abiotic soil modifications. This enhanced growth may be caused by <em>Senecio</em> leaf litter elevating nutrient concentrations in an otherwise nutrient-poor substrate. If such increased plant growth is a general phenomenon, further expansion of <em>S. inaequidens</em> could accelerate natural succession in European coastal dunes.本数据集用于完成Van De Walle等人2022年发表于《Neobiota》（待刊）的论文《入侵植物长舌千里光（Senecio inaequidens）对沙丘构建关键种沙鞭（Calamagrostis arenaria）的分布与影响》中的分析工作。欧洲海岸沙丘中长舌千里光的存在/否数据（PA）存储于文件"Senecio_PA.xlsx"的"senecio_PA"工作表中，同时包含记录该物种出现的国家与采样点位信息。该文件同时涵盖5m、10m、20m及50m四种不同尺度下的空间参数（占比P与联结计数H），以及尺度与参数的组合命名规则（如P_5代表5m半径圆形样地内沙鞭植被盖度占比）。所有采样点的坐标信息均存储于"coordinates samples"工作表中。 "Marram_growth_experiment.xlsx"包含生长实验期间采集的全部数据。沙子来源通过三列信息进行细分："Location"代表比利时海岸的沙子采样点位，"senecio"列标注沙子是否采集自长舌千里光植株下方（="bkk"，为荷兰语对S. inaequidens的俗称“BezemKruisKruid”的缩写），"biota"列则表示土壤生物是否会影响沙鞭生长（biota=0代表沙子经过灭菌处理）。 实验测定指标包括："numb_leaves"为叶片数量，"length_leaves_end"与"length_roots_end"分别为实验结束时测得的最长叶片与最长根长度，"leaves_fresh_end"与"roots_fresh_end"为新鲜叶片与根系的鲜重（单位：g），"leaves_dry_end"与"roots_dry_end"为叶片与根系的干重（单位：g），所有指标均为实验结束时的测定结果。 **摘要** 一般认为，干扰会提升入侵物种的定殖概率，这是其实现归化的前提条件。海岸沙丘以沙子动力作用为典型干扰特征。本研究以欧洲海岸沙丘为研究对象，探讨该类干扰对入侵植物长舌千里光定殖与扩散的影响。当地沙子动力作用决定了沙鞭（Calamagrostis arenaria）的空间构型，因此本研究以沙鞭构型作为干扰程度的可靠替代指标。鉴于沙鞭在自然沙丘形成过程中发挥关键作用，本研究同时评估了若长舌千里光能够在欧洲海岸沙丘归化，其对沙丘形成过程可能产生的影响。 我们曾推测，长舌千里光的定殖概率在沙鞭盖度处于中等水平时最高：盖度过低会加剧沙埋，而盖度过高则会加剧种间竞争。但研究结果表明，长舌千里光对高强度沙埋具有较强的耐受能力。因此，低沙鞭盖度环境下长舌千里光的定殖概率较高，而高盖度环境下定殖概率略有降低，这提示种间竞争的重要性。我们曾预期，长舌千里光改变的土壤会通过土壤生物群落介导，对沙鞭生长产生负面影响。但实验结果显示，采集自长舌千里光植株下方的沙子中，沙鞭生长状况更佳，这归因于非生物性的土壤修饰作用。这种生长促进效应可能源于长舌千里光的枯落物提升了原本贫瘠基质中的养分浓度。若该现象具有普遍性，则长舌千里光的进一步扩散可能会加速欧洲海岸沙丘的自然演替过程。