Reproduction Biology of an Alien Invasive Plant: A Case of Drought-Tolerant Aster squamatus on the Northern Adriatic Seacoast, Slovenia

Abstract

To understand changes in biodiversity, we must take into consideration at least the effects of global warming like increased droughts, the shift in plant phenology with the lengthened vegetation period, and the possibility that alien species might benefit from them. For better predictions whether non-native species could benefit from global change and turn into invasive alien species we chose to study Aster squamatus, alien that is already present in Slovenia and is currently regarded as non-invasive. We studied the species’ reproductive success and micro-scale habitat properties. Results show high reproductive potential of A. squamatus and it is necessary to constrain accumulation of seeds in the soil seed bank for future invasions. According to habitat properties, especially C:N ratio, we can regard A. squamatus as an engineering species, fertilising its own habitat. Climate change, prolonging the vegetation period, would enable more biomass accumulation followed by rapid decomposition. Released nutrients can be better used by fast-growing species that start their development slightly later in the season than early spring species, which begin to grow by utilising nutrients from their storage organs. In such cases of engineering alien species, adapted management is needed.