Biodiversity Conservation Laboratory, Department of Environment, University of the Aegean, 81100 Mytilene, Lesvos, Greece.
Department of Geography, University of the Aegean, 81100 Mytilene, Lesvos, Greece.
Sci Total Environ. 2022 Jan 20;805:150314. doi: 10.1016/j.scitotenv.2021.150314. Epub 2021 Sep 14.
Mediterranean islands are considered especially vulnerable to biological invasions by alien plants. However, there is a lack of studies on island scale regarding the factors that determine alien plant's spatial distribution, and the way they affect invasion process. A roadside survey of alien plant species was conducted on Lesvos, the 8th largest island in Mediterranean basin. Data on species counts and explanatory variables were aggregated to a 1 sq. km vector grid and brought together into a single GIS layer. Alien species counts were modelled by using a Negative-binomial model while a Generalised Additive Model was used to examine possible non-linear relationships to the predictors by using splines. A subset of significant factors, related both to human activities and the environment, shaped the spatial distribution of aliens and influenced, in various ways, their future invasion outcome. Transformed areas with high levels of anthropogenic pressures and disturbances, including high population numbers, dense road network, ports, and intensive land use, as is the case for coastal zones, promoted the presence of alien species. Contrary, modified areas, such as grazed lands, seemed to restrict alien species occurrences, possibly due to the long grazing history these areas present, a regime in which aliens are not adapted. Alien plants presence was positively associated with high levels of NPP, diversity of geological substrates, and a west-facing aspect. Anthropogenic determinants of alien spatial patterns were primarily connected to increased propagule pressure, whereas environmental factors demonstrated the preference of alien plants for resource-rich environments.
地中海岛屿被认为特别容易受到外来植物的生物入侵。然而，关于决定外来植物空间分布的因素以及它们如何影响入侵过程的岛屿尺度研究还很缺乏。在地中海盆地第八大岛莱斯沃斯岛，对路边的外来植物物种进行了调查。将物种计数和解释变量的数据汇总到一个 1 平方公里的矢量网格中，并汇集到一个 GIS 层中。使用负二项式模型对外来物种的数量进行建模，同时使用广义加性模型通过样条函数检查与预测因子的可能非线性关系。一组与人类活动和环境有关的重要因素，塑造了外来物种的空间分布，并以各种方式影响了它们未来的入侵结果。经过改造的、具有高人为压力和干扰水平的地区，包括人口数量多、道路网密集、港口和密集的土地利用，如沿海地区，促进了外来物种的存在。相反，经过改造的地区，如放牧地，似乎限制了外来物种的出现，这可能是由于这些地区长期放牧的历史，外来物种在这种情况下无法适应。外来植物的存在与高水平的 NPP、地质基质多样性和西向方面呈正相关。外来物种空间格局的人为决定因素主要与增加的繁殖体压力有关，而环境因素则表明外来植物对外源资源丰富环境的偏好。
